RF dash and sending unit harness dieting

[JohnK]

I'm deep-diving into the RF harness schematics and working through my strategy to wire the dash (Speedhut vintage gauges). I've seen several threads on the pro's and con's of using the RF harness vs. the supplied Speedhut wiring for the sending units. Supposing for a moment that I decide to use the Speedhut wiring for the sending units, then it seems to me that I could eliminate the following from the RF harness:

- entire sending unit harness (red box on left of schematic).

- everything from the large connector on the dash harness, with the exception of (1) brown gauge feed, (2) white dash lights, and (3) light green gas sender. The clock memory would go from the clock gauge to the coyote HAAT wire and all other gauge feeds would come from the Speedhut wiring.

This approach lets me eliminate the entire sending unit harness, as well as the large connector on the dash harness (and all its associated wiring.). The three wires that I do need I could re-crimp onto a smaller Molex connector and save all that space.

I've gone over this a few times in my head, and I don't think I need any of those other wires. Am I missing something important with this approach?

[phileas_fogg]

You are correct.

Note that you can re-purpose the electric choke circuit to power something else, like a cigarette lighter or seat heaters. I like the lighter because you can plug any number of adapters (USB, lightning, 12V power) into it.


John

[JohnK]

Thank you. Yes, I'm planning to repurpose the electric choke to power the E-Stopp electric parking brake. 10A fuse is perfect for that.

[Jeff Kleiner]

Thank you. Yes, I'm planning to repurpose the electric choke to power the E-Stopp electric parking brake. 10A fuse is perfect for that.

That’s fine but understand that the choke is only hot with the ignition on, so that means if you want to apply the parking brake after you’ve shut the car off you won’t be able to. Something you might want to think about...

Jeff

[JohnK]

That’s fine but understand that the choke is only hot with the ignition on, so that means if you want to apply the parking brake after you’ve shut the car off you won’t be able to. Something you might want to think about...

Jeff

Wow - that's a great catch - thanks! No, that won't work. I need something that's accessory -fed. I'm going to use the heater circuit for the heated seats, so I may use the radio circuit for the e-brake.

[Jeff Kleiner]

Wow - that's a great catch - thanks! No, that won't work. I need something that's accessory -fed. I'm going to use the heater circuit for the heated seats, so I may use the radio circuit for the e-brake.

Again, that will only be hot with the key on. Consider using the radio MEMORY wire which is energized all the time and is fused.

Jeff

[JohnK]

I think I'm OK with the e-brake only being powered when the key is in the accessory position. I'm installing a Digital Guard Dawg keyless ignition system, so the accessories will only be powered when the key fob is present and the accessories powered on. This gives another measure of theft protection, as the e-brake won't be able to be released unless the key fob is present.

[JohnK]

One more gauge feed-related question: Any issue with running the alternator power wire in the same bundle as the gauge feed wires, or will that cause interference in the gauge sender signals?

[edwardb]

I think you're making a mistake not powering the e-brake from a battery circuit. Think of the same as your headlight/running/courtesty lights, horn, brake lights. All work whether the key (or DGD) is on or not. For safety reasons. I'd put the e-brake in the same category. FWIW, that's how daily drivers with electric e-brakes are wired.

One more gauge feed-related question: Any issue with running the alternator power wire in the same bundle as the gauge feed wires, or will that cause interference in the gauge sender signals?

No.

[JohnK]

Thanks for the input Paul. This not necessarily the case, at least for my daily driver. I just went and checked, and the photo below is what I get if I try to disengage the PB without the key fob in my DD. I will definitely give this some more consideration, as nothing is cast in stone yet. However, I can think of many reasons why I don't want people to be able to disengage the parking brake without me present (i.e., without the DGD key fob present) but I can't think of many good reasons why the e-brake would ever need to be disengaged without the fob present. You're familiar with the DGD system, so you know that even in the event that I needed to have the car towed and had lost the fob, there's a PIN code that you can use with the DGD to start the car.

It's entirely possible that there are scenarios I haven't considered though. Do you mind elaborating on why you think this is a safety issue?

Thanks,
John

[edwardb]

Thanks for the input Paul. This not necessarily the case, at least for my daily driver. I just went and checked, and the photo below is what I get if I try to disengage the PB without the key fob in my DD. I will definitely give this some more consideration, as nothing is cast in stone yet. However, I can think of many reasons why I don't want people to be able to disengage the parking brake without me present (i.e., without the DGD key fob present) but I can't think of many good reasons why the e-brake would ever need to be disengaged without the fob present. You're familiar with the DGD system, so you know that even in the event that I needed to have the car towed and had lost the fob, there's a PIN code that you can use with the DGD to start the car.

It's entirely possible that there are scenarios I haven't considered though. Do you mind elaborating on why you think this is a safety issue?

Thanks,
John

You're right. I need to modify my DD comment slightly I guess. I worked in the industry where those were developed, so have some familiarity. There was a lot of safety discussion, and I know in order to pass regulations they had to operate all the time (e.g. a battery circuit) just like a manual e-brake would. Much of that before cars got as sophisticated as they are now. But with many cars having keyfobs and keyless ignition, makes total sense that would be integrated. Our Lincoln SUV has an electric parking brake, and I know it at least sets with the engine off. Makes sense they would add logic that it can only be released if the engine is running. Haven't tried that. But also all of that happening with the key fob around. So I suspect is similar to your DD.

Maybe part of the answer is what you consider the brake to be. Is it a parking brake? If so, by definition you would have the car running when operating. If it's really an e-brake (emergency) you wouldn't want it limited to only when the car is running. You'd want it available any time, e.g. car is rolling unexpectantly, whatever. Your choice. I know how I would set it up. But not going to argue or get emotional about it.

Also maybe explain a bit about the DGD. I'm very happy with it and would probably use it again if I went keyless in a build. But don't expect the level of sophistication that even the most basic DD's have now. It's a very simple step device. One button push ACC1, two button push ACC2, push and hold (with brake down) and car starts, push and hold (with brake down) and car stops. You don't have to use the ACC1 or ACC2. You can go directly to brake down and solid push to start. But you have to go through these exact steps. If you don't, it will get confused. (Or maybe it's the operator that gets confused...) But if there's one thing I'm a little disappointed with is the keyfob function has a quite long range. Modern cars have the system tuned so it only picks up the keyfob at certain locations and with very limited range. The DGD, being a more universal system, doesn't have this luxury. Mine picks up the keyfob if it's anywhere in the garage. And even sometimes in the house. If I'm anywhere near the car (e.g. at a car show) it's picking up the keyfob pretty much all the time. So I leave mine in manual mode. That means rather than the system being ready to start just by the keyfob being in the area, I have to push the button on the keyfob first. Then the red light on the start button lights and the system is ready to go. In either mode, it arms automatically after 5-10 seconds when the engine is turned off. So you don't have to do anything different there. You can switch the remotes individually between manual and automatic. So you can see what works best for you. Hope that makes sense.

[JohnK]

Thanks Paul. I understand where you're coming from now. I'm pretty diligent about setting the parking brake when I park in any car, so I was reading your comment as it being a safety issue if someone can't release the parking brake without the fob. You're right that if the PB isn't set when the car is parked, there might be instances where it might need to be set later for safety reasons. There are definitely trade-offs on this one. I have to admit that I'm a bit spoiled with my DD, which automatically sets the PB whenever I shift the car into park, and releases the PB whenever I shift into D or R.

Maybe part of the answer is what you consider the brake to be. Is it a parking brake? If so, by definition you would have the car running when operating. If it's really an e-brake (emergency) you wouldn't want it limited to only when the car is running. You'd want it available any time, e.g. car is rolling unexpectantly, whatever. Your choice. I know how I would set it up. But not going to argue or get emotional about it.

Now THIS is another can of worms. the E-Stopp has an ignition trigger wire that you can choose to connect or not. If it's connected, you can't set the PB when the engine is running so it's truly a parking brake and not an emergency brake. If you choose not to connect the wire then it's available as an emergency brake but you assume the risk of accidental engagement if the button is bumped while driving. I've located the dash button on the left side of the steering wheel. There's nothing else over there other than the headlight switch, so it's pretty unlikely that it would get accidentally bumped but I'm still very much of two minds on how I feel comfortable wiring this feature.

Thanks for the insights on the DGD system. That's interesting about the range being as large as it is. There are some features I wish it had, like the ability to turn on lights when you approach, but if the range is as large a you say it makes sense why they didn't implement something like this.

[phileas_fogg]

...you have to go through these exact steps. If you don't, it will get confused...

Yep. If you don't follow those EXACT steps, DGD gets confused.

When I do dork up the steps, my unit starts "clicking" to let me know it's in an anomalous state. Otherwise, I'd be really confused!


John

[RBachman]

John,

If I remember correctly, E-Stopp recommends a direct-to-battery power circuit to prevent interference. Mine is wired through a relay actuated by the ignition switch in "run" position. This energizes the circuit but only when on. However, I wanted more of a parking brake than E-Brake and, like you mentioned, it's a tad extra protection. Especially when a thief wouldn't know what switches dxid what. LOL.


I like incorporating the E-Stopp into the wireless system, though you may consider using a relay to better isolate the E-Stopp from potential interference.

Thank you. Yes, I'm planning to repurpose the electric choke to power the E-Stopp electric parking brake. 10A fuse is perfect for that.