Hello everybody,

I am brand-new to this forum and glad to be here.

I have a 1994 Chevy C 2500 with a 7.4 L motor and automatic.
In order to improve the quality of the wiring, I replaced and cleaned the ground straps from the frame to the firewall, the back of the engine – transmission to the firewall and the ECM ground connection to the thermostat housing.
Unfortunately, I did not remove the battery post ground – so I don't know if I had damaged the ECM or the prom – because the truck runs very poorly as if one was to remove three spark plug wires.
I have followed the procedure that if you'd lost power and information to the ECM, it would restore information on its own by following the running procedure.
Does not throw a code.
It has not and I am lost as to how to proceed. Aside from this mistake, I know vehicles fairly well.
Thank you and I be very appreciative of any information to move forward.
Thanks again, Craig

 

you can't damage anything by replacing grounds.
Likely you just reset a few calibrations in the computer, and it will take a bit of driving for them calibrate again.

 

To clarify - I did not remove the negative ground cable off the battery before removing the other grounds.

How long as I have run and driven about 25 minutes so far?
Thanks, Craig

 

a few drive cycles

 

It’s unlikely anything was permanently damaged but you may have caused some kind of glitch.

Try disconnecting both battery cables and clamping/jumper them together for about an hour. This will clear the adaptive memory but not hard data such as Passlock or software updates that have been done.

After reconnecting the battery, drive for 10-15 miles at highway speed so the PCM can relearn adaptive values - use cruise control if equipped.

Expect a minor rough idle and mild harsh gear engagement/shifts at first. It will help to cycle the gear shift through all the manual positions before driving.

 

I remember a ground on the rear of the transmission/engine was very close to the power wires routing to the starter with a metal sleeve and had been taped as appeared abraded and repaired before. I will look at it again when able.

Thanks, Craig

 

Hello and thank you gentlemen,

After much checking several connections and researching with other people, I found that the right bank temperature sensor for the cylinder head had some corrosion on the terminal and was able to clean it and repair the truck.

Now my frustration and intense irritability has lessened and I am now proud Owner of a decent running truck.

Thank you again for all your assistance and do take care,
Craig

 

Thanks for the update - glad you got it figured out.

 

Changing the damaged RT bank temp sensor - has a different one on both the terminal and the sensor into the coolant then the LT side. Are they interchangeable with the terminal connection changed?
I bought an expensive one that is an exact replacement for the LF side.

Thanks, Craig

 

A picture would be helpful to give you an accurate answer.