warthogcrewchief

On the way to work this morning, I had a CEL come on. Took it to Autozone to get the code pulled. They tried three times and could not get it to read anything. It still misses at idle, but the rpm is steady at 600rpm.i don't think it's an ECM. I've disconnected the negatite battery terminal and letting it sit for 20 minutes (10 minutes remaining). I'm not expecting much, other than a temporary reset. Has anyone else had this problem or know what it might be? Thanks!

oldchevy

If the code reader isn't reading it could be a blown fuse. I have heard that the cigarette lighter fuse also controls the CEL. Check that and all the other fuses if it is not the cigarette lighter fuse.

warthogcrewchief

Checked all the engine related fuses. I'll look for the accessory fuses.

warthogcrewchief

Looked the fuses over again. Nothing out of the ordinary. I did see there is a DRL fuse. I pulled that to turn off my DRLs. Easy fix for killing the DRLs.

Yogi

I had this very symptom/condition on my Suburban shortly before a valve lifter failed and wouldn't hold pressure. The engine would run fine and have a slight miss until the day the lifter completely failed. After the lifter failure I got a cylinder misfire code and the engine went into limp mode. Cost to repair at the dealership was well over $500. Not sure if this is your problem. But, the tach on my Suburban would show a slight and quick drop while engine was running smooth. Hope it's not the problem. But, thought any info gained could help you.

tech2

if the scan tool won't power up check the LTR fuse in the underhood fuse box like oldchevy suggested. The left front lighter outlet is powered by the same fuse; so if the lighter socket doesn't work also...the fuse is blown. If the scan tool won't communicate with the ecm try communicating with the bcm.

warthogcrewchief

I have three cigarette lighter/12v power outlets on the lower center dash. All work fine and no fuses blown. I pulled the battery terminal yesterday afternoon. I've driven it about 25 miles so far and the CEL has not come back on. . . yet.

I'm going to go to O'reilly's (just next door to Auto Zone) and have them see if they can connect to the ECM.

warthogcrewchief

I went to the other parts store to see if they could get it to connect. No joy. No fuses blown, no CEL light on since I pulled the battery (40+ miles now).

The only thing I can think of is to locate the ECU/ECM and look for any disconnected, cut, or damaged wires. I may even consider replacing the ECU/ECM as they're going for less than a $100 reman.

I don't like the idea of replacing the ECU/ECM as it is most likely still good, and I hate shooting from the hip for troubleshooting/repairing.

Does anyone have any good troubleshooting tips for determining if the ECU/ECM is bad?

Thanks!

tech2

What are you describing? Only 2 things can be happening here. Either the scan tool will not power up or the scan tool powers up but cannot communicate with the modules.


When they connect the scan tool does it power up? If it does power up is the message something along the lines...cannot communicate?

if it won't power up check for power at the data link connector pin 16 the orange wire. it should have battery voltage during key on.

warthogcrewchief

It appears it is getting power because the scanner reads 12v. It seems to be an issue with it not communicating with the ECU/ECM.