Electrical question

[WileE7]

Hey I'm not sure if any of you have run into this issue or can help me fix this problem. I have a 1990 EB Bronco with a C6 transmission it originally had the AOD. The guy I bought it from swapped the transmissions not sure why. To start it I have to turn the ignition and then press a switch under the dash for it to turn over. It's working like that since I bought it in 2005. I had the transmission rebuilt in 2024 I tried to find a harness to connect the transmission so I don't have to deal with the switch anymore I haven't had any luck. Last year I bought a 2021 badlands and my EB has been sitting until recently. I went to start it a few months and it just clicks. I replaced the battery and starter is good and I can start it from the starter solenoid. I was messing with it last week and the fuel pump was bad, replaced the pump and it will start at the solenoid but still nothing with the switch. A few days ago I tried to start it and the fuel pump wasn't working, I went to check the fuel pump relay and the PCM relay was warm. I'm going to order a new relay because that one looks ancient. Trouble shooting electrical problems isn't one of my strengths so I'm not sure where to start. Any help or suggestions would would be greatly appreciated.

 

[L\Bronco]

Hey While
Huge Bugs fan!
Sounds like the previous owner did a lazy mans bypass of the neutral safety circuit. If I had to guess, I’d bet it was a poorly done job and its failing. Its pretty normal for the Eec power relay to be warm if the key has been on for a while. (No harm in being sure though)
It’s also pretty hard to predict a failure point without seeing the wiring job.
As a start, I would suggest you check for 12v at the add-on push button with the key turned and the button pressed. (Both terminals should be live at this point.)
Once you get it to start from the key (and button) again, we can rig up a bypass relay that activates from the brake switch to make it a bit more normal.
If you really want to fix it, you will need the C-6 neutral safety switch installed (with the connector and pigtail(harness) attached)
Then we would have to find the plug for the Aod neutral switch and wire the c-6 one into that harness. Then it would start normally and you’d have backup lights as well. (I assume they dont work either)
Good luck with it
Cheers

 

[WileE7]

The back up lights don't work and it will start in any gear. I'll post pictures of the wiring job soon.

 

[L\Bronco]

Sounds good, Ill watch for it.
Cheers

 

[WileE7]

If you need more/clearer pictures please let me know

 

[L\Bronco]

Wow! That looks like a dogs breakfast down there!
The good news is the bones are good.
The plug in the 1st pict is the Aod neutral safety switch plug. I assume the 2 wires plugged into it go to your aftermarket dash switch for starting. The last pict looks like the C-6 neutral safety switch. It should have 4 or 5 wires though.
Im not sure why all the wires are twisted together like that. (Probably someone trying to get it to crank with a field fix.)
If you get a new C-6 neutral safety switch, we should be able to decode the wire colors on the AOD plug and the C-6 switch, make a few connections (properly) down there, and everything should work normally.
I feel that, given the open
connection-ness down there, (I believe in the “if you dont have a word for it, make one up” philosophy), there are likely a blown fuse or 2 in the panel.
Should be very do-able!
Cheers!

 

[WileE7]

The current NSS has 2 wires the few I've looked at online have 4. That should make things a little easier for wiring.

 

[L\Bronco]

Yep

 

[Jimbo26]

If you need more/clearer pictures please let me know

Things that make ya go-

 

[Jimbo26]

Things that make ya go-

Public floggings in the village square should be brought back.

 

[WileE7]

Here's the new NSS. It has 2 red wires with a blue a black wire with a red stripe and a purple wire with an orange stripe.

 

[johnnyreb]

That looks like the same neutral saftey switch on my 78 Bronco. I mounts on the driver side of the transmission. IF the wire IS the same----the wire will tralel up behind the top of the motor on the MID TO PASSENGER SIDE. Where they connect into some more wires. CHECK THE CONNECTION AND FOR A BROKEN WIRE OR TWO. It caused me alot of troubles and was hard to find.

 

[L\Bronco]

Here's the new NSS. It has 2 red wires with a blue a black wire with a red stripe and a purple wire with an orange stripe.

Looks right. When I get a min, Ill find a diagram to decode the colors for you on the nss and your truck, it should be pretty straightforward
Sorry for the delay, busy at work and on the funnycar.
Cheers