94 Chevy corvette ecu ground location?
Thread Starter
Cruising
Joined: Dec 2022
Posts: 12
Likes: 0
From: Louise
94 Chevy corvette ecu ground location?
Seems like I’m not getting any power to my injectors and I’ve read that this is a problem with the ecu ground? Am I correct? Has fuel/ spark. Plenty of fuel pressure
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
The 94 uses a PCM, not a ECM, big difference.
The injectors get voltage with key on all the time thru fuses 22 & 23. The return wire get grounded thru the PCM when the engine is running or starting to fire the injector.
So first check to see if you have voltage on the injectors. If not check the fuses. Then use a noid light to see if they are being driven (grounded) by the PCM.
If the noid light flashes, that means the PCM and the opti are basically operating properly.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 812
From: Saskatoon Sask.
No, no, no
The 94 uses a PCM, not a ECM, big difference.
The injectors get voltage with key on all the time thru fuses 22 & 23. The return wire get grounded thru the PCM when the engine is running or starting to fire the injector.
So first check to see if you have voltage on the injectors. If not check the fuses. Then use a noid light to see if they are being driven (grounded) by the PCM.
If the noid light flashes, that means the PCM and the opti are basically operating properly.
The 94 uses a PCM, not a ECM, big difference.
The injectors get voltage with key on all the time thru fuses 22 & 23. The return wire get grounded thru the PCM when the engine is running or starting to fire the injector.
So first check to see if you have voltage on the injectors. If not check the fuses. Then use a noid light to see if they are being driven (grounded) by the PCM.
If the noid light flashes, that means the PCM and the opti are basically operating properly.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
The PCM has a programmable PROM, cannot be replaced and programming can be changed thru the ALDL connector. The ECM has a replaceable plug in PROM.
One of the differences big differences is that the ECM batch fires the injectors (batch firing). In other words one bank of injectors (4) all fire at the same time, and then the other set fires.
With the PCM it is sequential firing. Just like spark plugs are timed to fire one at a time, so are the injectors. A much better system all around.
Another change was heated (electrically) O2 sensors. With hot sensors all the time, the O2 keeps working keeping the mixture correct at all time. Where if they get cold like at an idle or such, they can stop working and don't give proper feedback voltage back to the ECM to correct the air fuel mixture to the correct ratio.
Racer
Joined: Jan 2016
Posts: 290
Likes: 78
Replaceable prom and eeprom as well as different programming parameters aside the main differences between Engine control modules and Powertrain control modules is the ecm only has control over the engine and a few other non engine functions, i.e. converter lock-up, a/c compressor relay, etc. pcm on the other hand will have multiple controls integrated into the same module…engine and trans with communication to and from the other modules through out the car. 94-95 pcm’s had more functionality in them then earlier ecm’s (I’m talking about all cars in general) as they were a precursor to OBD2’s release in 96.
