AEM/OEM wiring

[BaadVR4]

When I swapped the drive train from my 95 VR4 to my wife's 95 VR4 (18 months ago), my son noticed a wire in the ECU wiring which had been run to ground in the cabin. His 95 VR4 had an AEM installed (different shop) but the wire was not hooked to ground in his car. Her car would not start until we grounded the same wire in her car. It then ran fine.

My car sat until about 6 weeks ago when I put a stock motor in. When I put the stock ECU in, the battery was already hooked up. Lots of things (AEM wide band/digital AC controller/don't know what else) seemed to cycle. Turned key to start. Lights dim, don't even get a click. Used a screwdriver to short power lug to solenoid lug, engine turns fine so I used a remote start tool to prime the oil system (35 psi with no spark plugs in) and then did a compression test a few hours later (140-150 on all 6). Disconnected stock wire to solenoid at the plug under the battery. Even with solenoid wire disconnected, turning ignition switch to "start" causes all the lights to dim.

At this point I suspect a short somewhere, so I set up a 30 amp relay at the starter, ran ground side to a push button in the cabin. I can now push a button to activate the relay and turn the engine with the starter.

My questions are:

1. Any idea why the wire was grounded in the cabin of my car?

2. Should I disconnect the ground wire in my car? I'm thinking the wire was grounded for something specific to the AEM installed in my car/wife's car (the AEM wouldn't work in my wife's car until we grounded the same wire). And the AEM install in my son's VR4 was done differently and didn't need the ground hooked up. I'm worried I may have already damaged my ECU by turning it on with the ground wire connected.

3. Will I be able to start/drive the car by putting key in "run" and using the push button/relay to crank the engine? If I have fuel pump issues, will I be able to solve them by hot wiring the pump with a relay hooked directly to the battery (30 amp fuse, operate relay with a toggle switch on the ground side)?

Any/all help greatly appreciated. Thanks in advance,

Milt

[BaadVR4]

Here's the wire:

[2fnloud]

Milt,

I need to know what the stripe color is on that light green wire.

Also this is a Fed/Can car right? Not a California car?

[2fnloud]

OK with Bob's (OhioSpyderman) help I have been able to identify that clip is the C-54 clip, that light green wire should have a black strip, Milt can you confirm this?

[BaadVR4]

It has a black stripe.

[2fnloud]

OK Milt that wire goes to the EGR Temperature Sensor (Pin 1) the only other pin of that sensor (Pin 2) is a ground (well it is connected to other sensors but it is a ground wire).

[DocWalt]

Like Steve said, that wire is the EGR temperature sensor. Disconnect the ground and reconnect the two ends of the light green/black wire. I'm unsure if that's related to the starting issue. You can definitely start the engine using the starter with the key in the "run" position, it's just like push starting it.

[BaadVR4]

Like Steve said, that wire is the EGR temperature sensor. Disconnect the ground and reconnect the two ends of the light green/black wire. I'm unsure if that's related to the starting issue. You can definitely start the engine using the starter with the key in the "run" position, it's just like push starting it.

Thank you. I'm pretty sure the issue with turning the key to "start" is something separate from the wire being hooked to ground. Even with the wire to the solenoid disconnected, turning the key to "start" results in the lights dimming/etc.

In addition to the wire from the ECU harness being run to ground, I'm thinking I need to reverse all the other splices/cut wires that were part of the AEM/MAP sensor/AIT install. Then I might be able to get this thing running.

[2fnloud]

Thank you. I'm pretty sure the issue with turning the key to "start" is something separate from the wire being hooked to ground. Even with the wire to the solenoid disconnected, turning the key to "start" results in the lights dimming/etc.

In addition to the wire from the ECU harness being run to ground, I'm thinking I need to reverse all the other splices/cut wires that were part of the AEM/MAP sensor/AIT install. Then I might be able to get this thing running.

That would be the first thing I would do before anything.

[DocWalt]

That would be the first thing I would do before anything.

+1 on this