Hotwire wiring question

[darto]

Hello all,

I’m in the process of installing the Hotwire harness on my 6.1/nag1 combo. The Hotwire harness has a “pink” colored wire that needs 12v unbroken between switching from start (key on) and run. I know there isn’t a constant hot from the ignition switch (key on) for both start and run.

I plan on combining the blue Ign1 and brown Ign2 wires from the back of the ignition switch to accomplish this. Is this correct?

Has anyone used this combination of wires to get constant 12v between start and run? Or have they ran a switched wire from somewhere else?

Thanks

 

[408 swinger]

I think that will backfeed the system. I have read that some have used a capacitor inline on the Run 2/Start circuit. I have not tried this, but, can't see why it wouldn't.

 

[DionR]

The switch has a moment where neither the blue nor the brown wire is powered which looks to the PCM as if you turned off the key. So joining the blue and brown isn't a good solution by itself. There are relays and other options that would hold power for a brief second that would fix it, but I haven't looked into them.

Easiest solution is to wire the pink wire to the blue wire, never turn the key to the start position and only to the run position, and wire in a momentary switch to the starter wire.

You can also bolt in an F-Body ignition switch, but you have to re-wire it at the plug to make it work.

 

[darto]

@DionR Thanks for the advice!

 

[68cuda408]

if you don't have a constant 12v post on your ignition switch (run/start), I have, on a couple efi conversions and hemi installs just run another wire from the starter post (on the switch) with a diode to prevent current from returning to the switch. Splice the new wire and the run wire and both circuits will energize constant. If the diode is backwards the starter will crank in run position.

 

[darto]

if you don't have a constant 12v post on your ignition switch (run/start), I have, on a couple efi conversions and hemi installs just run another wire from the starter post (on the switch) with a diode to prevent current from returning to the switch. Splice the new wire and the run wire and both circuits will energize constant. If the diode is backwards the starter will crank in run position.

Thanks for the information! Do you happen to have a specific diode that you would recommend?

 

[68cuda408]

I'll check stash tomorrow. They are coded. I use black with silver band

 

[68cuda408]

I've also used IN4007's, they are more robust. Using 2 dedicated wires from the ignition switch to the EFI constant voltage lead, the diode allows crank request current to not interfere with run current and blocks run current from re-energizing the crank circuit.

 

[moparmarks]

I used a Hotwire in a 5.7 E body. I connected the brown and blue wires together. I didn't know about using a diode. It starts and runs fine. ???

 

[68cuda408]

I've done this also, but I have seen some older ignition switches that the crank wire was not isolated

 

[moparmarks]

I don't understand why this would be a problem. When the switch is in the start position energizing the #2 brown ignition wire the terminal in the switch for the blue wire is open. Also both the brown and blue wires get their power from the same power wire on the line side of the switch.
I also do the same connection when running an MSD ignition.

 

[DionR]

I don't understand why this would be a problem. When the switch is in the start position energizing the #2 brown ignition wire the terminal in the switch for the blue wire is open. Also both the brown and blue wires get their power from the same power wire on the line side of the switch.
I also do the same connection when running an MSD ignition.

I know this is kind of bringing this back from the dead, but thought maybe it would help at least someone to answer the question.

The reason connecting the blue and brown wires together can be a problem is because within the switch there is a break between the 2 contacts, so when the switch is moving back from the start position to the run position neither wire is powered. For some electronics (and maybe switches) this break in power isn't long enough to cause an issue, but for others it is an eternity and the module thinks the key was turned off. For a PCM that is running the coils and injectors, this results in the motor shutting off rather than staying running.

For an MDS module, I can't imagine it would matter. But for some EFI computers, it is.

 

[moparmarks]

Didn't seem to affect the Hotwire PCM that I used.

 

[DionR]

Didn't seem to affect the Hotwire PCM that I used.

Could be your switch is better than others. Who knows. Not saying it happens for every situation.

Here is a clip from Hotwires instructions:

Just trying to make people aware so that if it is a problem, they have ideas where to look.

Either way, I prefer to avoid potential problems, so if I was going to run the switch in the column, I would fix it so it can't be a problem.

To each their own.

 

[loganscuda]

Not sure what year your car is but mine is 67 and had to add a push to start button. If you call Hotwire they will tell you how to best do this. Their tech was was really good 14years ago when I did mine. Hopefully still the same.