My ECM is throwing out a code 28(Quad-driver module #3), which is a A/C relay or Fan relay error. I just replaced my relays and the fans only come on if I turn the A/C on, so I am thinking my ECM is bad. My question is where can I find the best quality and prices on a ECM?

It is a 93.

Thanks,
Randy

 

Only 28 I'm familiar with is for the tranny but GM sometimes uses different codes for different models. In any event, quad failures are rare as they are fail safe devices, shutting down if there's a problem with the circuit or device and some scanners/literature mislead you into believing there's an ECM failure. If you changed out the relays with key on or the circuit powered up, that may have generated a code and it would have an "H" in front of it. If you haven't, clear it and see if comes back.

Both fans should come on anytime the a/c is on. Otherwise, the parameters are something like 218 degrees for the main; 226 degrees for the secondary (and I'm working from memory here, so these may not be exact). BUT, the same ECM driver turns on the fans whether the signal is from the pressure switch (a/c operation) or coolant temp sensor (non a/c) so you might want to investigate a little further before you swap out the ECM because the driver is obviously working.

If you verify that it's the ECM, they're available at the Discounters for about half of what the Dealers charge and you can get pricing online at sites such as www.autozone.com (aftermarket reman) or the Last Detail www.tld-corvette.com (a/c delco reman - which is all the Dealers offer).

 

Thanks, I got the code info from Corvette doctor and Chevy dealership. If I don't turn on the A/C the car overheats. So, I am going with what everybody tells me.

 

ECM,.... your basic part store item. Just make sure it is covered by a warrenty.

 

I'd just make sure then that the temp sensor is working and not skewed or that there isn't high resistance in the coolant signal circuit. Were there any driveability or starting problems? Assuming it's ok, then it's needs a new ECM and I don't believe the replacement gets the Federal Emissions warranty mandate of 8 yrs/80k - just 30 days (by most) once that time period has expired.