2G ECU harness wiring, grounds

[chrysler kid]

Putting a 99 ecu in my 98, I realize there are some differences but I would really like a second opinion before I put everything back together

The 99 was clone of my car, gst leather auto with infinity sound. It had ground wires on the bolt to the ecu. It's the two black wires under the ecu bolt behind the wires

My 98 did not have those wires. Top picture was the parts car in the junk yard

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Also on my 98 under the wire wrap for the first plug, the power plug makes a u turn after a black cheap looking crimp connector, the black ground does it as well, I'm thinking that's for the starter or mpi relay? Can anyone confirm? It looks sketchy and the mpi or starter relays had an intermittent click issue before. I have not touched the wiring or molested it, I wanted to check here first

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[chrysler kid]

Hunch pays off!

It's way under the center console, in the middle under the center hvac stack by the firewall.

I've never seen a ground connection this bad before

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I'm really hoping this is it. The car ran and idled amazing with the new ecu, but I could tell after it warmed up it would get out of closed loop and act like it had no fuel. The engine harness kept looking at me funny. Really hope this was it, the ECU ground cable

 

[spyderdrifter]

So in theory, all of us probably have that ecu ground somewhere right?

 

[chrysler kid]

So in theory, all of us probably have that ecu ground somewhere right?

It's more like the ground for the main interior harness.

In the factory service manual (for a 98 talon) it shows the ground on the drivers side of the radio stack. In this 98 gst the ground is on the bar that holds the plastic center console panels to the dash

For reference my car was having problems starting, clicking coming from behind the radio when no start condition. It also was tripping the security alarm, it would randomly go off. All electrical lighting at night had a pretty drastic flicker to them.


So if your car has any of these symptoms check the ground from the engine harness inside the car. My car is a southern car so the rust is from a.c. condensation


I'm still chasing gremlins, slowly eliminating them. The egr valve was stuck open, causing the car to smoke, the pcv valve is dripping oil into the intake, and the heater doesn't work. One day this project will be done

 

[Busdownthotiana]

I hate to revive a dead thread since I am on this same adventure of a no start and discovered this ground as well. I still have to clean mine up but am wondering if this solved your nostart issue so this can be a resolved post. This would be excellent to add to the resolved no starts! Thank you for this post!

Also I’m adding some pictures to pin point where exactly this ground is because I actually struggled for about 30 minutes to understand that you meant UNDER .

These pictures are from the passenger side right by the glove compartment and center console. Follow your wiring harness towards your shift cluster whether auto or manual and you’ll see a few wires loose from the large wiring harness. You should pretty much be directly under the area of your radio and the hvac “stack”.

On the metal base where every plastic piece is mounted there is this ground where you receive your ground and from the colors it seems as though- your fuel pump grounding wire comes from here.

Just speculation no idea. But I’ll clean mine up with some apple cider vinegar(any vinegar will do) in a cup and place this terminal and submerge it into the vinegar which will remove the green corrosion. After that I take some baking soda and water into another cup and clean off the acid bath.

Finally I take some sand paper to any matte looking brass or copper and wipe dielectric grease and clean the surface to protect it from the air/corrosive humidity.

If you take a close look I need to also do the same with dielectric grease and coat this ground area. It’s hella rusty. I don’t know whether this will solve my injector pulse issue being documented on my build but if you’re interested you can follow my build for a no start due to no injector pulse.

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[Busdownthotiana]

Did all this with some basic formula science. Consider it a science project! The acid transforms or converts the corrosion to an ammonia, the baking soda and water neutralizes the solution creating a surface that’s basically brand new. Well, it sat in the solution for a hr. It had a tarnish that was not green. The brand new picture is after you take a wire brush to it. It literally restores it to almost factory if you want to call it that. Just place some dielectric grease on it. Spread it all over the copper wires so it’s coated.

I cannot take credit for the idea as I’ve learned it nerding out. This is a priceless trick I used back when my fuel pump had rusted thoroughly. Being cheap I decided to restore it with some toilet bowl cleaner trick. It worked! But I had a hard time preventing it from rerusting. I bought a new gas tank.. and the cable connecting the actual fuel pump in the tank to the module that connects to the mpi relays etc was corroded and I couldn’t get my pump to fire. I took apart that connector and dipped it in this solution. It’s been working just as it did and I actually did have to do this I believe twice to my gas tank. To be fair I just used regular marine grease cause I had nothing else. It’s actually worked just fine I checked it again before I started my diagnosis of the the “things”.

Hopefully one person learned how to do that.

Also the formula was on some YouTube video I believe and there was a guy in the comments who actually made another video of the whole solution based on balancing a chemical equation. Idk who likes learning but it was a cool trick that imo is better than just taking some sandpaper to the terminal which actually will work. But the plus for me is the wires inside the sheathing can also be benefited.

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