Turn signal issues w/engine running

[Dubai33Ford]

Gents,

One more strange one for you all. The turn signals and hazards work fine with the engine off, however, with the engine running they just flicker, stay on, flicker some more, work fine a few moments and then flicker on and off.....so basically all over the place....

I tried changing the flasher ground a few times as well as the power source. No luck so far.

Ideas?

Cheers,

[wallace18]

Sounds like a loose connection to me. The vibration of the engine running may be causing the poor connection . I would check all wire connections. Also put a voltmeter on the flasher hot wire and see if it is steady or not.

[NAZ]

Niagara Dave had a similar issue & traced it to the coil wire. I believe he ran the coil wires through the same loom as the turn signals which lead to electrical noise interfering with the turn signals. In aircraft it is common to run twisted pairs of wires in a shield to prevent electrical noise from interfering with critical electronic systems. If you find this is the cause, simply twisting the positive & negative wires together a turn or two per inch may be enough to reduce the interference.

[mopargolfer]

I have this problem too and just noticed it after the car is mostly assembled so will be hard to fix. Turn signal works fine with engine off and comes on solid or flickers occasionally when engine on. Talked to factory five, Ron Francis, MSD and all say never heard of it. Not sure why more folks aren't seeing it unless its related to the engine configuration. Mine is carbureted with an MSD Blaster coil. Wire from the fuse box goes directly to the coil +. No other ignition. Possibly using an MSD ignition my fix this where the coil wire would go to the ignition, not the coil.

4 way flashers work fine, engine on or off. Uses all the same wiring other that gets power from a different fuse. Turn signal fuse is two fuses away from the coil fuse and the 4 ways are fused off the brake fuse at the other end of the block. Other than that no difference.

Anyway I ran a wire direct to the battery from the coil and the problem went away. MSD says coil can't cause this problem and I must have a ground issue. Ron Francis says grounding issue also. They say I need to run a ground from the battery to the engine block. Contrary to the way the kit directions say to ground everything to the frame. Factory Five doesn't have any advice.

I would be interested in the actual solution to this problem if anyone have actually fixed it.

[BikingJohn]

I do not believe the issue is noise from the coil. The coil is simply not drawing enough current to generate a magnetic field large enough to cause your turn signals to stop working. I suspect the issue is a resistive connection (probably a ground), that is where I would start troubleshooting. When it is just your turn signal there is not enough current flowing to drop significant voltage across the resister created by bad connection. When you start the engine the current draw increases and so does the voltage drop. You can test this by placing the ground lead of a voltmeter to the negative terminal of your battery, and with your turn signals on and engine running place the positive lead to all connection points in each respective circuit, starting with ground side. Each connection point should be 0 volts, if something other than 0 then it is resistive and needs to be redone until it reads 0. For the positive side each circuit apply the same principal but this time you will be looking for a large voltage change from one connection point to the next. This change indicate something in the circuit is resistive or a bac connection if you will. Also make sure the motor and other electrical systems in your car have a common grounding point to the frame. Hopefully this helps, good luck.

[mopargolfer]

Thx for the response. I have had 4 people, including the tech at MSD, tell me there should be no noise issue yet I have found 3 other folks on different forums that have or had this ussue using LED turn signals. I have 3 solutions to the problem now as I fixed it today.

1). Make sure the turn signal fuse is not on the ignition portion of the fuse box AND is at least 4 inches away from the coil fuse. Problem...turn signals are traditionally on the ignition fuse bank.

2). Move the coil wire out of the fuse box by connecting to the battery. Problem..can't shut car off but it does fix the problem...If you want to be able to shut the car off I tried a relay which connected the coil to the battery but did not work. I believe because the coil connects to the relay and is so close to the relay trigger wire going to the fusebox that is still got bleedover from the coil. When I did this the relay itself was 2 feet from the coil.
I was surprised this did not work.

3). I installed an MSD ignition today with the goal of keeping any noisy circuits under the hood and out of the fusebox. This worked perfectly as the connection to the fusebox from the MSD is only to turn it on when the key is set to ignition. Practically no amps. All the power comes through a connection to the starter battery wire. don't have an O scope to prove its noise but it sure seems like it and proves out with the testing I did. The LED flashers are all electronic, different than an incandescent bulb flashers and electronics are affected by noise so this is more proof. However as I said 4 people told me this can't be so I don't know, just glad it's fixed.

Thanks for the insite on checking the grounds and power connections, That will be very useful. I'll go through the entire car tomorrow and see what I see but everything else is working great.

[mopargolfer]

Thx for the response. I have had 4 people, including the tech at MSD, tell me there should be no noise issue yet I have found 3 other folks on different forums that have or had this ussue using LED turn signals. I have 3 solutions to the problem now as I fixed it today.

1). Make sure the turn signal fuse is not on the ignition portion of the fuse box AND is at least 4 inches away from the coil fuse. Problem...turn signals are traditionally on the ignition fuse bank.

2). Move the coil wire out of the fuse box by connecting to the battery. Problem..can't shut car off...even moving this wire with a relay which connected the coil to the battery did not work. I believe because the coil connects to the relay and us so close to the relay trigger wire going to the fusebox that is still got bleedover from the coil. When I did this the relay itself was 2 feet from the coil.

3). I installed an MSD ignition today with the goal of keeping any noisy circuits under the hood and out of the fusebox. This worked perfectly as the connection to the fusebox from the MSD is only to turn it on when the key is set to ignition. Practically no amps. All the power comes through a connection to the starter battery wire. don't have an O scope to prove its noise but it sure seems like it and proves out with the testing I did. The LED flashers are all electronic, different than an incandescent bulb flashers and electronics are affected by noise so this is more proof. However as I said 4 people told me this can't be so I don't know, just glad it's fixed.

Thanks for the insite on checking the grounds and power connections, That will be very useful. I'll go through the entire car tomorrow and see what I see but everything else is working great.

[Sharkman]

Thx for the response. I have had 4 people, including the tech at MSD, tell me there should be no noise issue yet I have found 3 other folks on different forums that have or had this ussue using LED turn signals. I have 3 solutions to the problem now as I fixed it today.

1). Make sure the turn signal fuse is not on the ignition portion of the fuse box AND is at least 4 inches away from the coil fuse. Problem...turn signals are traditionally on the ignition fuse bank.

2). Move the coil wire out of the fuse box by connecting to the battery. Problem..can't shut car off...even moving this wire with a relay which connected the coil to the battery did not work. I believe because the coil connects to the relay and us so close to the relay trigger wire going to the fusebox that is still got bleedover from the coil. When I did this the relay itself was 2 feet from the coil.

3). I installed an MSD ignition today with the goal of keeping any noisy circuits under the hood and out of the fusebox. This worked perfectly as the connection to the fusebox from the MSD is only to turn it on when the key is set to ignition. Practically no amps. All the power comes through a connection to the starter battery wire. don't have an O scope to prove its noise but it sure seems like it and proves out with the testing I did. The LED flashers are all electronic, different than an incandescent bulb flashers and electronics are affected by noise so this is more proof. However as I said 4 people told me this can't be so I don't know, just glad it's fixed.

Thanks for the insite on checking the grounds and power connections, That will be very useful. I'll go through the entire car tomorrow and see what I see but everything else is working great.

For those who have same problem as stated above my fix was to supply the coil from the battery but use the the current orange RF wire to the coil to trigger a Bosch solid state relay that source is battery feed. I also have a MSD distributor and Blaster 2 coil. This fixed my problem. Hope this helps for anyone who also runs into this problem.

[MonstaS4]

My 2 cents worth based on experience with industrial control systems:

It's the low frequency switching in the coil wire which induces noise into other circuits. A typical ignition coil has a primary resistance of around 2 ohm which equates to approx. 7 amps.

When you have relatively high current wires and a signal switching frequently, running in parallel with low current signals - e.g. LED indicators (<0.2 amp) - you'll get interference if not using shielded cables. Normal incandescent globes are 21w (1.5A) so are not as susceptible to interference.

As NAZ mentioned, you could use shielded, twisted pair cable for the coil, and earth the shield at one end only to avoid ground loops.