OBD-II Code P1374 on a 1996 Olds Cutlass Ciera 3100 (rough idle/skip/dies)

I got a hold of the GM troubleshooting rundown, which looks just like the alldata steps, except in some steps it says something like "refer to the Wiring Repair in Electrical Diagnosis book" so I was wondering if you had such a thing. At this point it's looking like there's a very complex electrical problem we need to attept to trace down, or the computer is bad :(

-GV

I highly doubt a fuel additive would be throwing a P1374 code.

Slightly better with the new ICM however the symptoms have not changed, the problem still exists. Came from autozone, brand new.

Highly unlikely, this wasn't a pickup from a junkyard this was a brand new part.

That's the last thing we want to do. A *new* computer is $350 and would need to be reprogrammed.

For the symptoms, AND a P1374 code, though??

Nope. Car had just passed inspection and had an oil change, actually.

After it started this problem and the check engine codes came on the first time, we gave it a good tuneup (as per my original post) plus we replaced the MAP sensor due to a P0108 code (IIRC). As I posted already, this is either a wiring/terminal problem we are going to attempt to trace down, or it's the computer. It doesn't appear to be the ICM (as this did not solve the problem and the P1374 code is still there) and it's definitely not something as over-simplified as just someone adding fuel injector cleaner.

-GV

Gotcha. If you have the factory manual set there is a book dedicated to Electrical Diagnosis. The wiring repair you speak of is just a section detailing repair procedures. Nothing specific to any circuit. I can turn the ALLData version of the same thing in a PDF, but it's not going to help you until you find the problem.

...or if there is a specific piece of information you need, I could send that over...

Steve

Sorry I can't be more specific, I'm just reading what the printout we got from the GM dealer says. Anything you can post would be helpful and much appreciated!! :)

-GV

You know, I just can't f'n win. Went to the library today, they have all the mitchell manuals EXCEPT the one for 1996 in one section, and in another section they have mitchell manuals that have these wonderful wiring diagrams that would probably be great EXCEPT the thing is in this big binder and none of the librarians know how to undo it to make copies, because you can't take it out of the library!!

-GV

Use a digital camera and photograph the pages. Also a trip to

might be in order. If you plan on keeping the vehicle and fixing it yourself a good set of factory manuals is well worth the investment....

how much does the boneyard want for a puter.and why did the wiring problem suddenly develope?connectors?corrosion?chafing?insulation failure?constant flex internal breakage?unbelievable fluke?(my VW)if you were able to cure the other codes it does seem like a funny deal.wonder why the new ICM only improved the running.can new parts be faulty.it does happen occaisionally.maybe i'll go study that 1374 repair tree.

The answer to all your questions is: I don't know. The car was running fine when my friend first got it, all of a sudden the check engine light came on and it started running like crap. We have not yet ruled out a wiring problem or a computer, yet. We got past step 4 in the alldata chart posted by Steve Mackie, now we are on step 5 (that means we did not skip to step 8 if you are following along). Simply ran out of time tonight, will be working on step 5 in the coming days.

-GV

well if i'm understanding this 1374 thing(pdf)so far your car is currently running on the 24x reference signal(crank sensor) and cam signal.1374 means the ICM is ignored(3X) as an input to PCM.so then why did the car run better with a new one?hmmmm.and even without ICM input car should start and run on 24x and cam signal.you replaced the crank sensor.you joked about the cam sensor.hmmmm.

After lots and lots of frustration, I believe we've found the problem, it appears to be a bad wire. The circuit 430 wire, purple/white, has no continuity. That's the 3x reference high signal for those following along at home. And, obviously I got my hands on the wiring diagrams (finally) or else we never would have figured this out.

Now of course, the question is, what type of wire is used, what gauge of wire is used, and how in the hell are we gonna run the wire from under the hood to the inside of the car? And after all that, is this finally going to fix the problem...I certainly hope so.

-GV

well,hows it goin.got it licked yet?

Nope. Replaced the wire that was bad, the P1374 code still throws. We give up, it's going to the shop tomorrow.

-GV

Still not solved yet. Shop found 3 bad wires (which they fixed) which also fried the computer. Replaced computer, took to dealer for reprogramming, car still acts up, bucking, stalling, cutting out, etc. Have not put it on the code scanner just yet to see if it's the exact same code or not yet. Man this problem is just a total bear...any experts out there want to take another crack at this one? Or do we just flat out have an unfixable problem here?

-GV

Every problem has a solution.

Seems odd that you found bad wires, maybe there is more. Was one of the bad wires going to the crank sensor? Were the bad wires repaired properly? Why were there bad wires? Maybe there is an underlying issue no one is addressing.

Steve

Not sure exactly which bad wires were fixed, the shop fixed them, they just said 3 bad wires, behind the alternator if I'm not mistaken. As far as I know the 3 bad wires were repaired properly. I'm not 100% sure why or how the wires went bad. Something about the 3 wires were rubbing and shorted out which fried the computer. Also, got a chance to scan the codes again after I got it home. P1374 code came up twice, and P0108 came up once. P0108 indicates MAP sensor, but that's already been replaced.

-GV

Was the MAP sensor the case of the P0108?

We replaced the MAP sensor because the p0108 code came up before. Now it's coming up with 2 P1374 codes and 1 P0108 code. It's currently back at the shop that "diagnosed" it. They are going to be eating the labor until they find out exactly what the problem is, I'm beginning to wonder if it really was the computer after all at this point.

-GV

So replacing the MAP didn't fix the P0108?

The first step in diagnosing a P0108 asks "Is the idle rough/unstable etc?" "If so, repair idle first before trying to diagnose P0108."

Steve

Actually in the troubleshooting for the P0108 code, it states that if you have a P1374 code to fix that first and see if it goes away. We replaced the MAP sensor anyway because it was relatively inexpensive, but at the end of the day it really didn't solve anything. The dealer (that reprogrammed the computer) is of the opinion it could be the harmonic balancer (aka vibration dampener) because "it's a common problem" they see in their shop. We took the thing off to replace the crank sensor on this car, and it seemed fine to me, so I doubt that's it, but of course I could be wrong. Unfortunately a new one is $70!

-GV