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Thread: fan sensor PROBLEM SOLVED !!!!!!!!!!!

  1. #1
    herb fraser's Avatar
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    fan sensor PROBLEM SOLVED !!!!!!!!!!!

    HI <I am using the factoryfive supplied wiring harness , can seem to get the cooling fan to come on , any thought would be helpful , thanks herb
    see my last reply
    see my last post
    Thanks to everyone, who needs a stinking manual when we have this great forum
    Last edited by herb fraser; 01-14-2019 at 10:31 AM.

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    BadAsp427's Avatar
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    First of, you can test the fan system by grounding the switch wire either at the top of the engine where the thermo switch is located or at the fan connector. You should have a "temp switch" wire at both of those places. Grounding that wire simulates the thermo switch turning on and completing the circuit.

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    herb fraser's Avatar
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    Quote Originally Posted by BadAsp427 View Post
    First of, you can test the fan system by grounding the switch wire either at the top of the engine where the thermo switch is located or at the fan connector. You should have a "temp switch" wire at both of those places. Grounding that wire simulates the thermo switch turning on and completing the circuit.
    Oh, so if I do that the fan should come on , correct ? and of course if it does them the fan is not the problem, makes since , will keep you posted, Thanks , Herb

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    herb fraser's Avatar
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    OK so I by passed the sensor by grounding the sensor wire and still no fan , so it must be somewhere in the wiring harness ? any thoughts ?

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    Papa's Avatar
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    Do you have a way to power the fan directly? I'd suspect the fan before the harness.

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  7. #6
    herb fraser's Avatar
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    Quote Originally Posted by Papa View Post
    Do you have a way to power the fan directly? I'd suspect the fan before the harness.

    Dave
    good thinking will try that later !

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    Senior Member phileas_fogg's Avatar
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    Three quick tests off the top of my head:

    1. Jumpers straight from battery + and - terminals to fan. If fan is good, it should run.

    2. Pull fan fuse and test for continuity. While fuse is out, test to see if you've got +12V at fuse socket.

    3. Test to see if you've got +12V at fan spade connector (dark blue wire of RF front harness). With thermo switch wire grounded, test to see if you've got ground at fan spade connector (black wire in RF front harness).


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    herb fraser's Avatar
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    Quote Originally Posted by phileas_fogg View Post
    Three quick tests off the top of my head:

    1. Jumpers straight from battery + and - terminals to fan. If fan is good, it should run.

    2. Pull fan fuse and test for continuity. While fuse is out, test to see if you've got +12V at fuse socket.

    3. Test to see if you've got +12V at fan spade connector (dark blue wire of RF front harness). With thermo switch wire grounded, test to see if you've got ground at fan spade connector (black wire in RF front harness).


    John
    will do , thanks

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    Papa's Avatar
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    If the fan works when powered directly, check the fan relay. You can swap it with the horn relay if you don't have an extra lying around.
    Last edited by Papa; 01-12-2019 at 02:09 PM.
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  11. #10
    herb fraser's Avatar
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    OK so just tested the fan and it works fine so somewhere in the wiring
    will run the other tests later today

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    Like Papa said,.... Try swapping out the relay with the horn relay. And then do the grounding wire thing you did first... The grounding of the wire should activate the relay that will in turn power your fan. IF that doesn't work, you will need to start tracing wires and be sure that the connections between the harnesses is good. I actually had one wire in the RF harness that did not have a good connection through one of the connectors.

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    Sometimes it something really simple Herb (read stupid on my part). Check to make sure the connector from the main harness to the front harness is plugged in. I had unplugged one to get better access to some other wiring in a roadster foot box and had forgotten to plug it back in. Just say'n

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    herb fraser's Avatar
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    Quote Originally Posted by i.e.427 View Post
    Sometimes it something really simple Herb (read stupid on my part). Check to make sure the connector from the main harness to the front harness is plugged in. I had unplugged one to get better access to some other wiring in a roadster foot box and had forgotten to plug it back in. Just say'n
    this is true I have done the same ,but in this case it connected

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    Senior Member Scott Zackowski's Avatar
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    Just is case you have things wired incorrectly, here is some helpful Fan Wiring information I got from Jeff Kleiner. It is vey simple. Also I highly recommend wiring in a fan "on" indicator dash light. It is impossible to tell the fan is on when the engine is running.

    Jeff's Words
    I'll suggest a simple alternative that doesn't require modifying the harness. Wire it with the manual dash switch using the brown "fan switch feed" wire for power in and the orange "cooling fan" wire that carries a switch signal to the relay. You'll find both of these wires are in the dash harness. If you want an indicator light (I like to use an amber one to show when it is on) tap one side of the lamp into the orange and take the other side to ground. Now, for automatic operation pick up a Painless thermostat switch. It is a true, normally open thermostatic switch with two female spade contacts, not a grounding switch. Wire it in parallel with the manual dashboard toggle; i.e. one side to the brown feed wire the other to the orange load wire. Screw it into a coolant port in the intake or thermostat housing and you're done; no reconfiguring of the relay as would be necessary with the FFR supplied grounding switch and the entire circuit is still protected by the 30 amp "cooling fan" fuse. Simple as that--- you will now have automatic as well as manual fan control and an indicator light to let you know anytime the fan is running! Painless switch #30111 turns on at 185* and off at 170* (perfect for a 180* stat) but there are others available with different on/off setpoints.

    Painless Wiring 30111 - Painless Performance Temperature Sending Units - Overview - SummitRacing.com


    Here is the link for this info and it also includes additional dash wiring information that is very helpful:

    http://www.ffcars.com/forums/17-fact...-question.html
    Last edited by Scott Zackowski; 01-12-2019 at 02:30 PM.

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    herb fraser's Avatar
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    just checked and there is no power at the fuse on either side, so thinking easy way out would be to rewire it and install a new 30 fuse , but my next question would be can I run this setup without a relay using the sensor that came with it
    Last edited by herb fraser; 01-12-2019 at 02:30 PM.

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    Senior Member Scott Zackowski's Avatar
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    Quote Originally Posted by herb fraser View Post
    just checked and there is no power at the fuse on either side
    Herb:

    Review your wiring and connectors. Make sure you have it wired correctly.

    Scott

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    Quote Originally Posted by herb fraser View Post
    just checked and there is no power at the fuse on either side, so thinking easy way out would be to rewire it and install a new 30 fuse , but my next question would be can I run this setup without a relay using the sensor that came with it
    Herb,

    I posted a response in the 33 forum before I saw this one get traction. The fan circuit is a negative control circuit. There should always be +12 volts on the positive side of the fan. The relay controls the ground, completing it when it gets a trigger from the sensor at the specified resistance for the sensor. Only pin 85 should have +12v on the fan relay circuit.

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    Well Used Member boat737's Avatar
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    Quote Originally Posted by Papa View Post
    Herb,

    I posted a response in the 33 forum before I saw this one get traction. The fan circuit is a negative control circuit. There should always be +12 volts on the positive side of the fan. The relay controls the ground, completing it when it gets a trigger from the sensor at the specified resistance for the sensor. Only pin 85 should have +12v on the fan relay circuit.

    Dave
    Are you sure about that? My understanding is that the RELAY is a negative (ground) control circuit. Once a ground is supplied to the relay, that relay will close and provide +12V to the fan. That's how mine is anyway. (I also have a second relay in that circuit to prevent back current as the fan spins down after shutdown. That's another topic though...)
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    Quote Originally Posted by boat737 View Post
    Are you sure about that? My understanding is that the RELAY is a negative (ground) control circuit. Once a ground is supplied to the relay, that relay will close and provide +12V to the fan. That's how mine is anyway. (I also have a second relay in that circuit to prevent back current as the fan spins down after shutdown. That's another topic though...)
    I'm not sure. Bowing out ...
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    herb fraser's Avatar
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    Quote Originally Posted by Papa View Post
    Herb,

    I posted a response in the 33 forum before I saw this one get traction. The fan circuit is a negative control circuit. There should always be +12 volts on the positive side of the fan. The relay controls the ground, completing it when it gets a trigger from the sensor at the specified resistance for the sensor. Only pin 85 should have +12v on the fan relay circuit.

    Dave
    More fun, so Dave do I understand you correctly that the blue positive wire in the front harness should always have power to it as long as the ignition is on ? because if that's the case there is no power and as stated before no power at the fuse either

  22. #21
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    Quote Originally Posted by herb fraser View Post
    More fun, so Dave do I understand you correctly that the blue positive wire in the front harness should always have power to it as long as the ignition is on ? because if that's the case there is no power and as stated before no power at the fuse either
    That's how I understand negative control circuits, but I honestly don't know if this is how the RF fuse panel is wired.

    This video explains it well:



    I'm going to stop adding confusion and hope that someone that knows for sure can help you. Have you tried to swap the relays yet? Does your horn work with the relays swapped? Just a couple of additional trouble shooting steps you can try.

    Dave
    Last edited by Papa; 01-12-2019 at 05:36 PM.
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    Senior Member CVOBill's Avatar
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    Herb,

    The temp sensor and the toggle switch (if used) will provide a ground to the relay. When the relay is grouned that will send power to the fan. So to answer your question the blue wire will only have power when the relay is closed.
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    herb fraser's Avatar
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    Ok now I am really confused but will work on it tomorrow. So tomorrow I will change out the relay. But am I correct in thinking that there should always be power at the fuse when ignition is on ?
    Last edited by herb fraser; 01-12-2019 at 08:03 PM.

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    Well Used Member boat737's Avatar
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    Quote Originally Posted by herb fraser View Post
    Ok now I am really confused but will work on it tomorrow. So tomorrow I will change out the relay. But am I correct in thinking that there should always be power at the fuse when ignition is on ?
    Maybe not. In my case at least, my Ron Francis harness and fuse panel has constant hot +12V to the relay, then to the (30A) fuse. (I don't really like the fuse after the relay, but that's the way it's wired on mine, and I didn't catch it.). I don't know if all of the RF harness's/fuse panels are always hot, or if some have it wired through the IGN on circuit, but in my case, I have a constant hot +12V coming into both the #30 and #85 terminals on the relay. A grounding source, either 1-block temp sensor, 2-radiator temp sensor, or 3-manual switch, will activate the relay and allow +12V to go through the fuse to the fan. So if you have one of the green (I think they are green) temperature sensor wires handy, ground one of them, and you should hear the relay switch close, and then you should have power to the fuse, which should also give you power to the fan. BTW, you don't need to pull the fuse to check. The blade fuses should have a small area in the head of the fuse to put a test light/meter probe. You have to look close, but there is a small little detent in the fuse head where the metal contacts are.
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    Senior Member SSNK4US's Avatar
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    So I can’t really say anything about it because I’m not there yet....but I think it’s time Jeff or Paul chime in (no offense guys) before Herb burns something up or melts something down lol It seems there are two different ideas going on here that are confusing Herb (and me). Be careful Herb.

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    Hi. I recently went through all this. Before you start tearing anything apart, do you know what year your rf harness came from? The earlier MK4’s and earlier had an orange “cooling fan wire” on the dash harness, to facilitate a manual override. If you have one of those and are not using a switch, you will need to close it off to. +12v source. (Brown “fan switch feed” wire). That orange wire is the other end of the gate circuit for the fan relay and allows the ground from the temp sensor to complete the circuit and let power flow through to the fan. If you don’t have that orange wire, then ignore my advice.
    Last edited by CFranks; 01-13-2019 at 08:58 AM.

  28. #27
    Senior Member frankb's Avatar
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    Herb:

    Speaking from the standpoint of the Mk4 with the RF harness, there should be +12v at the thermo switch terminal with the key in the "Run" position and the engine cold. If not, there is a problem in your "control" circuit. (See CFranks' comments above)

    With the key in the "Run" position and the engine cold, there should be 0v at the dark blue wire in the fan connector.

    Next, at the fuse block, check for voltage at the "Fan" fuse. There should be +12v on either side of the fuse (with the key either in "Off" or "Run"). If there is +12v on one side of the fuse, but not the other, the fuse is bad.

    If both the above check OK, set the key in the "Run" position and jumper the wire on the fan thermo switch to the block. You should now have +12v at the dark blue wire at the fan connector and the fan should start. If not, check that the black wire at the fan connector is properly grounded. If all these check OK, the issue is in your relay or the fan dark blue wire from the fuse block to the fan.

    Does this help?

    The below relay diagram applies...
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    Last edited by frankb; 01-13-2019 at 09:15 AM.
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  29. #28
    herb fraser's Avatar
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    Quote Originally Posted by frankb View Post
    Herb:

    Speaking from the standpoint of the Mk4 with the RF harness, there should be +12v at the thermo switch terminal with the key in the "Run" position and the engine cold. If not, there is a problem in your "control" circuit.

    With the key in the "Run" position and the engine cold, there should be 0v at the dark blue wire in the fan connector.

    Next, at the fuse block, check for voltage at the "Fan" fuse. There should be +12v on either side of the fuse (with the key either in "Off" or "Run"). If there is +12v on one side of the fuse, but not the other, the fuse is bad.

    If both the above check OK, set the key in the "Run" position and jumper the wire on the fan thermo switch to the block. You should now have +12v at the dark blue wire at the fan connector and the fan should start. If not, check that the black wire at the fan connector is properly grounded. If all these check OK, the issue is in your relay or the fan dark blue wire from the fuse block to the fan.

    Does this help?
    Hi Thanks, it helps, but there is NO power on either side of the fuse at the fuse box
    and no power at the black or blue line at the fan connector
    Last edited by herb fraser; 01-13-2019 at 09:15 AM.

  30. #29
    Senior Member frankb's Avatar
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    Herb: I will assume that if you have a battery cut-off switch, that it is "ON". If that is the case, it sounds like there is an issue with the power (heavy gauge red) wire connection on the back of the fuse block. Disconnect your battery, and drop the fuse block to take a look for signs of heat or corrosion on the wire terminals.

    Another question: Does everything else work, i. e. lights, etc?
    Last edited by frankb; 01-13-2019 at 09:35 AM.
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    Well Used Member boat737's Avatar
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    I believe we are talking about 2 different RF designs. My understanding is the later RF designs (like I have, mentioned above. My FFR chassis harness manual is Rev-L) use a grounding wire at either the block temp sensor or radiator temp sensor (or even a manual switch). The earlier ones (which I have no knowledge about, other than reading about them over the years on the forums) use a +12V power to activate the fan. I guess first thing to figure out is which one you have.
    Last edited by boat737; 01-13-2019 at 09:54 AM.
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    herb fraser's Avatar
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    have not tried lights yet but will today but the interior wire work like heater etc.
    Does the power got from the battery to fuse or to the relay first ?

    NOTHING <NO POWER going to the front harness , so now I will have to look for a problem with the connect for front harness or fuse box problem , its keeping my busy LOL
    Last edited by herb fraser; 01-13-2019 at 12:16 PM.

  33. #32
    Senior Member frankb's Avatar
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    The power goes directly from the battery (Bat post on the starter solenoid) to the high power supply (lights, fan) in the fuse box. It does not go through the Key switch.

    Frank B
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  34. #33
    herb fraser's Avatar
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    SOMETIHNG IS F UP,
    So here is where I am
    checked the relay fan and horn ,they work fine. I can here the horn relay click so I changed it with the fan relay, no luck
    none of the light wire are connect, nothing touching, when I pulled on the light switch the fuse instantly popped.
    the horn relay works but when I plugged in the horn nothing happened except that the relay clicked
    starting to drive me nuts !!!
    lost for words !

  35. #34
    herb fraser's Avatar
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    Quote Originally Posted by frankb View Post
    The power goes directly from the battery (Bat post on the starter solenoid) to the high power supply (lights, fan) in the fuse box. It does not go through the Key switch.

    Frank B
    so with or without the key turned on there is power to operate the fan and lights, this makes since

  36. #35
    herb fraser's Avatar
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    at this point I am not worried about the fan circuit , I can replace that with a new complete fan relay circuit for $20 , I know that is not the really the right answer but its an easy answer.
    I am just not sure now if the light circuit that keeps popping the fuse has anything at all to do with the horn not working and the fan not working ?
    again the relays are working fine
    Tomorrow I will contact Ron francis wiring and se what they say
    At this point I am hope full there is an easy answer!!


    all the gauges are working fine and so is the heating fan
    Last edited by herb fraser; 01-13-2019 at 12:22 PM.

  37. #36
    Well Used Member boat737's Avatar
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    Quote Originally Posted by herb fraser View Post
    none of the light wire are connect, nothing touching, when I pulled on the light switch the fuse instantly popped.
    Let's see if we can tackle these things one at a time.

    First, the lights fuse is blowing. Definitely something wrong there. Does it happen on the first position (running lights), or second position (head lights)? You said that nothing is hooked up on the lights circuits, so leave the fuse out, and get an OHM meter and test out either the running lights wires or the head lights wires (which ever circuit blows the fuse). There should be NO continuity to ground. If there is, there is a short, or most likely a wire that is connected to ground, when it should be connected to a user (i.e. a light bulb). There's probably 6 wires for the running lights, one each for the front L and R, and most likely 2 each for the rear L and R. There are also 2 power wires for the head lights, hi and lo beam L & R. With no fuse in, and the switch off, there should be no continuity to ground on any of them (and no light bulbs hooked up either, because you will show continuity to ground through a filament bulb if there is one hooked up in the system.)
    Last edited by boat737; 01-13-2019 at 12:54 PM.
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    Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch.
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  38. #37
    Senior Member frankb's Avatar
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    Since the gauges and heater power are controlled by the key switch, they are separate from the high power items like horn and lights which are supplied directly from the battery, So, your high power circuits are where you should spend your time...
    FFR MK4 #8317, 393 Cleveland, Lunati VooDoo solid roller, CHI 3V heads and intake, TKO 600, Std roadster seats, 8.8 3.55 diff, 17" Halibrand replica wheels, Ford "Magnetic Metallic", silver ghost stripe.

  39. #38
    Senior Member Big Blocker's Avatar
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    Herb,

    Throwing money at an issue isn't the way to go about troubleshooting . . . "I can replace that with a new complete fan relay circuit for $20 , I know that is not the really the right answer but its an easy answer."

    Lets get your fuses blowing issue fixed first. Pull ALL the bulbs for brake and turn signal (front & back), disconnect your headlights and try the switch again. IF you blow the fuse again there is a wiring issue that need attention immediately. IF the fuse holds, connect your brake light bulbs and step on the brake pedal - fuse holds? or blows again? Install your turn signal bulbs and try left and right turns - fuse holds or blows again? While you have all the lesser amperage bulbs inserted (correctly) and everything is good-to-go, connect one headlight and turn it on - fuse holds or blows . . . now install the other headlight bulb - fuse blows or holds. Anywhere along this circuit procedure, you will find the fault that is blowing your fuses. The process is to "isolate" the bad device and determine WHY it is causing your fuses to blow.

    Once you get these lower current draw devices to work, we can work on your fan circuit . . . which is probably the highest current draw circuit on the car.

    FWIW, your fan relay will work with or without the fan connected, and can be tested for "clicking" when you activate the temp sensor or ground the lead to it. If the relay is functioning, the issue may be that the relay isn't passing power to the fan (bad internal contacts?). This can be verified at the relay terminals 87 and 30 . . . 87 should have power when the key is ON, 30 when the relay is activated.

    Keep us posted and we will get this fixed for you . . . There is a tremendous amount of talent on this and the other forum . . .

    Doc
    FFR3712K (MKII) in Lost Wages Nevada.
    5.0 w/tubular GT-40 EFI, E303 cam, Custom 4 into 4 headers, T5, 3-Link 3.73 rear. Full F5 tubular suspension. Drop Butt mod, Dash forward mod, custom foot box air vents, custom turn signal system. 13" PBR brakes, Fiero E-Brake mod, Flaming River 18:1 rack w/ F5 bump steer kit on Breeze bushings. 17" Chrome Cobra "R's" w/ 275 fronts and 315 rears. MKIV seats. FORD Royal Blue w/ Arctic White stripes.

  40. #39
    herb fraser's Avatar
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    Quote Originally Posted by Big Blocker View Post
    Herb,

    Throwing money at an issue isn't the way to go about troubleshooting . . . "I can replace that with a new complete fan relay circuit for $20 , I know that is not the really the right answer but its an easy answer."

    Lets get your fuses blowing issue fixed first. Pull ALL the bulbs for brake and turn signal (front & back), disconnect your headlights and try the switch again. IF you blow the fuse again there is a wiring issue that need attention immediately. IF the fuse holds, connect your brake light bulbs and step on the brake pedal - fuse holds? or blows again? Install your turn signal bulbs and try left and right turns - fuse holds or blows again? While you have all the lesser amperage bulbs inserted (correctly) and everything is good-to-go, connect one headlight and turn it on - fuse holds or blows . . . now install the other headlight bulb - fuse blows or holds. Anywhere along this circuit procedure, you will find the fault that is blowing your fuses. The process is to "isolate" the bad device and determine WHY it is causing your fuses to blow.

    Once you get these lower current draw devices to work, we can work on your fan circuit . . . which is probably the highest current draw circuit on the car.

    FWIW, your fan relay will work with or without the fan connected, and can be tested for "clicking" when you activate the temp sensor or ground the lead to it. If the relay is functioning, the issue may be that the relay isn't passing power to the fan (bad internal contacts?). This can be verified at the relay terminals 87 and 30 . . . 87 should have power when the key is ON, 30 when the relay is activated.

    Keep us posted and we will get this fixed for you . . . There is a tremendous amount of talent on this and the other forum . . .

    Doc
    Thanks Doc, however none of the light are connected, just the pig tials and I made sure they were not touching anything

    Also , the fan relay does not click when grounded
    Last edited by herb fraser; 01-13-2019 at 01:25 PM.

  41. #40
    Papa's Avatar
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    Herb,

    I said I was going to stop contributing to the confusion, but here is one more thing to consider that I encountered during my initial wiring. I ran all the harnesses to their locations and, like you, had nothing connected to them. I found out two important things, completely by accident. First, my brake light switch was wired backwards and was providing power to the brake light wires, and second, those unprotected wires can short very easily just by their proximity (power & ground) as well as by hitting any part of the grounded chassis. Do yourself a favor and slip a short piece of heat shrink tubing over all the loose wires at the ends of the harness until you actually connect them to the items they are intended for.

    Again, sorry if I caused you any additional frustration and I know that the electrical gurus will get you fixed up fast!

    Dave
    There are 10 types of people in this world;
    those who understand binary and those who don't.

    My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754

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