I did not have a stock ECU bracket so I made my own at work today. I need to know if the ECU case needs to be grounded to the body of the car, becuase I've painted my bracket to discourage rust and thus at the moment the case is not grounded to the car.

thanks,
James

 

It may work without the ground because there is a ground wire to the ecu from the engine harness, but it should be grounded. Anywhere on the chassis would be fine.

Paul

 

+1, i think there are two ground wires that are supposed to go on the ecu bracket case

 

Oh dear I don't have anything grounded at the ECU. I do get the brake lights, gauge lights dimming out very slightly when I push the brake pedal.

So simple fix is to run a ground wire and attach it at the ecu preferably at one of the bracket bolts?

 

I will solder up a wire with eyelets on either end and run it from an ECU mounting screw to one of the body mounts. Here you can sorta see the bracket I made:



If anyone has a better picture of this area to show me how to route the wires in a more organized manner I'd love to see it. I'm putting my car together from a pile of parts so I never saw it in an assembled state.

thanks,
James

 

I'm sure that will work fine.

There is a sheet metal piece that covers the harness where it gos through the firewall and helps keep it tidy.

Paul

 

One more piece I don't have. Sigh.

 

One thing I just checked....

I used a continuity tester and ran it from one of the body grounds above the ECU to the ECU case and it showed continuity. So apparently it's being grounded through one or more of the wires in the plugs. I'm still going to make an additional ground for the sake of redundancy.

 

 

I definitely think you should ground it. Just in case one of the sensors uses frame ground for measurement (think of things like the stock single-wire o2 sensor)

Dave

 

Hey thanks guys. This was the last thing I had to figure out before re-installing the interior.

 

Ironically the power fc does not have a ground wire running to it unlike the factory ecu.

R.K.

 

yea i noticed that, but i grounded the old ECU wires to one of the vacant bolts from the stock ECU.

 

They both have a plain steel bolt going directly into the frame. That's the real ground. Don't let the ECU hang unattached or else it might won't be grounded - this I know from experience.

Dave