cls33

I'm having some problems with my '92 I'm hoping someone can help me with.

Symptoms:
Shortly after pulling out of my garage my "Service ASR" light comes on, and the "sys" and "security" lights on my dash flash. The "sys/security" lights then flash intermittently throughout the rest of the drive. Sometimes sporadically, sometimes continuously (every 15 seconds or so as the manual states will happen with a continuous problem), if the lights are flashing every 15 seconds, my digital gauges (such as engine temp) do not update during that time. Usually the continuous flashing will stop at some point during the drive and my gauges will begin working again.

The car drives fine during all of this, however if I stop it is very difficult to restart the car while it is hot. It either won't turn over, or it turns over and immediately dies. Starting the car while cold is generally not a problem.

I read the CCM codes and the most interesting thing in there is H41, which translates to "Lost communication between the CCM and ECM"

Cause(s) and fix(es):
I've done a small bit of reading on this and it seems like a not-uncommon problem. It's pretty clear that the CCM and ECM are experiencing some kind of a communication issue. Most people seem to state that this can be caused by a faulty ground connection or a bad ECM. I took a look at the wires going into the ECM and didn't notice anything pinched or frayed, and I looked at some of my ground connections, and they also seemed to be in good shape. So I'm kind of lost at what to do next. My only thought is to try replacing the ECM. I'm by no means a master mechanic, but it seems like an easy enough job. However, I'm having difficulty locating one online, it seems to be a rare part.

So... 3 questions:
1) Is replacing the ECM a logical thing to try?
2) What else should I be trying
3) Any tips on where I can get my hands on a 92 ECM for a reasonable price?

Thanks

0KEN W ANDERSON

[QUOTE=92vette3;1574975729]I'm having some problems with my '92 I'm hoping someone can help me with.

Symptoms:
Shortly after pulling out of my garage my "Service ASR" light comes on, and the "sys" and "security" lights on my dash flash. The "sys/security" lights then flash intermittently throughout the rest of the drive. Sometimes sporadically, sometimes continuously (every 15 seconds or so as the manual states will happen with a continuous problem), if the lights are flashing every 15 seconds, my digital gauges (such as engine temp) do not update during that time. Usually the continuous flashing will stop at some point during the drive and my gauges will begin working again.

The car drives fine during all of this, however if I stop it is very difficult to restart the car while it is hot. It either won't turn over, or it turns over and immediately dies. Starting the car while cold is generally not a problem.

I read the CCM codes and the most interesting thing in there is H41, which translates to "Lost communication between the CCM and ECM"

Cause(s) and fix(es):
I've done a small bit of reading on this and it seems like a not-uncommon problem. It's pretty clear that the CCM and ECM are experiencing some kind of a communication issue. Most people seem to state that this can be caused by a faulty ground connection or a bad ECM. I took a look at the wires going into the ECM and didn't notice anything pinched or frayed, and I looked at some of my ground connections, and they also seemed to be in good shape. So I'm kind of lost at what to do next. My only thought is to try replacing the ECM. I'm by no means a master mechanic, but it seems like an easy enough job. However, I'm having difficulty locating one online, it seems to be a rare part.

So... 3 questions:
1) Is replacing the ECM a logical thing to try?
No, not unless you have a spare one lying around.

2) What else should I be trying
The CCM sounds like your problem, but you need a competent diagnoses before you start spending money.

3) Any tips on where I can get my hands on a 92 ECM for a reasonable price?
We repair them for $275 w/ one year warranty, BUT, make sure that's the real problem

Jamesnns

Good idea to check your grounds, refer to yur FSM, or someone here will post graphics/pages you need to DX.

Do your trip cluster buttons work?
If not....
Mine was similiar...the connectors had come loose at the DIC causing C41 and really wierd symptoms and other codes. Take out your DIC ( Trip cluster) and make sure both connectors are secure.
Remove center console piece, remove stereo/ac trim/plate, remove center vent grill, remove DIC/trip cluster. Your DIC has two connections in the back. The larger one in center was kind of a pita cause it had to be pressure fitted...I ended up taking the connector out, connecting it, then putting the DIC/trip cluster back in..saved a lot of time. The smaller one was my culprit, but NONE of my trip cluster button worked or illuminated either...until i fixed it.
I'm so good at this now, I can remove all these parts in minutes ...lol.

Jamesnns

Screamin_conure has a 92 and FSM's.
PM him and ask to scan and send you the pages for C41 Dx.
He's a friend of mine and a good guy, tell him I sent you cause idk if he has a scanner...but I do.

I have a 91, so I will do it (scan and post c41 pages), it someone will post if it'll be the same or not?????

jaa1992

OP - A 92 ECM is scarcer than hens teeth. THey are made of unobtanium. Which is why I have 2, one to swap in whenever the FSM says "ECM problem" - rarely turns out to be an ECM problem though.

Ken - Can you describe in a couple sentences what your rebuild process entails? One of my ECM's is affected by heat and I'd like to get it fixed if your process sounds reasonable.
Please be specific on how you test a repaired unit and if the chip needs to be sent with the unit for repair.

screamin_conure

Do I have a scanner? Of course I have a scanner! What kind of IT geek would I be if I didn't have a scanner!

Hey 92Vette3, below are the two pages from the 1992 factory service manual for a CCM code 41:

Page 1



Page 2



Hopefully, these will help you out. From looking at the info in the manual, it appears as though you will need to access both the back of the ECM, and the back of the CCM. The ECM is under the hood, right in front of the driver side firewall, next to the brake master cylinder. The CCM is somewhere in the console, alongside/behind/next to the HVAC/stereo units. The manual instructs removing the driver's right knee bolster in order to access it. Good luck with that. The one and only time I had my center console out to repair my C68 unit, I was about ready to just light the car on fire about halfway through the process. I guess it gets easier after you've done it a few times, right James?

In looking at the diagram, two of the dozens of wires that connect to the ECM run back to a splice (S222) somewhere in the firewall/dash/console area I would assume. And from that splice, two wires run back to the CCM. I'm willing to bet that your issues are somwhere in that path and NOT a bad ECM or CCM. Like I mentioned, you'll need to locate the two ends of those connections and do some continuity testing. Just follow the troubleshooting chart (yeah, I know, easier said than done). This one is going to take some time to sort out. Just be patient and stick with it. If you do end up taking it to a mechanic, be sure to give him a printout of the FSM pages.

To answer your questions:

1) As mentioned before, NO. Unless you have absolutely determined that's where the problem is. I'd be REALLY surprised if that's what it is. I'm willing to be it's a wiring issue somwhere.

2) You should RUN, not walk, to your computer and log on to eBay and find yourself a copy of the '92 factory service manuals. If you have any intentions of keeping your 'Vette for any length of time, the $100.00 or so that you'll spend on those two books will be absolutely invaluable. If you spend some time reading through those manuals, and if you have even the slightest mechanical abilities, you'll be amazed at the kinds of repairs you can do yourself.

3) If you find that it actually is the ECM, I did find this place: http://www.autocomputersystems.com/f...showrnrattop=0. Click "Engine Control Units", pick your year/make/model from the dropdowns and it'll give you a list of available ECMs. Supposedly, they have #16159278 (that is the ECM for your '92) available. That's also about the best price I've seen as well.

Let us know how it goes, and good luck!

Ron

Jamesnns

Hey...I forgot to thank you for the beer yesterday...Thanks!

And yes, I'm the quick draw of taking a vette dash apart...practice makes perfect.
It's really not that hard once you do it 10-15 times....

cls33

Great information! Thanks a ton!

I'll carve out some free time in the next few weeks and see what I can track down.

Guitarguy

i just sent my ecm to this place http://www.siaelec.com/index.asp?Pag...D&ProdID=38817 $45 to test if its good. $175 to rebuild, no test fee.

4953mark

thanks for all your help

Jamesnns

YW..

Did this work for you?

4953mark

My car is still at the chevy dealer

what brand and or type scanner should I buy?

thanks mark

qwiketz

I realize this is a pretty old thread, but I am getting the c41 error and this post is interesting. I recently replaced the shifter cable and the car ran and drove. Shortly there after it wouldn't. I'm going to dig into the dash and see if any of the connections mentioned above are loose or disconnected. Interesting info.

Jamesnns

Good luck. The dash can be tricky the first time getting into it. After that its really easy. Im curious if this works for you. Post an update. Thanks

Den14

Here is a strange one for you. I had the same problem with the H41. I traced all the connections and even went as far as to test the continuity of all the concerned parties in the loop. Used the FSM to do all of the troubleshooting. Turned out to be a bad connection to the coil. Might explain the no/hard start when its hot too. There is also a ground that goes to the front of the block from the Tach filter if I remember correctly that should be checked as well, and it's right there in plain sight. After I cot the connection on the coil seated properly, it fired right up and no more h41. The ICM can also be a culprit if it's heat related. The h41 can occur because it's not getting the signal to "run" within the first few seconds, so there IS no communication between the ECM and CCM . While the car is running, give the wires in the area of the ICM and coil the wiggle test and see if it dies or stumbles. As I mentioned before, this is based solely on my own experience with the H41.

93C4Vroom

I had the same issues with my 93. SIA fixed it by reflowing the solder on the circuit board of the ECM. Common problem in 92 and 93. 94 and after had different design. Good luck. Mine runs great now.

qwiketz

We're there any specific issues that you experienced with your car prior to getting the computer fixed? How did you diagnose the problem? Did you narrow it down by testing some of the other things and if so what did you do to narrow it down?

93C4Vroom

I read a lot of posts on this board and others. I found that there were people having he exact issue and codes. Piggy backing off of their experiences, I took a shot at the ECM. I did speak to the tech person at SIA and they said it was pretty common issue. Over time the solder cracks from the hot/cold cycles and age. The ECM works fine until it gets hot enough to expand the connections and then it responds with "Service ASR" and the flashing "Security". Then it won't start if you shut if off. Wait 15 minutes and it starts. Or, as some had done here, put a bag of ice on the ECM and see if it starts.

I thought about other issues and didn't want to start a wild goose chase of hunting down every possible cause of the malfunction. Loose/bad grounds. Bad connectors. I check what I could and they seemed fine. The big clue was that it always started after it cooled down sufficiently. Also, it ran fine when the warning lights were on.

Check the 92 and 93 vettes. The have a distinct looking ECM. 94 and beyond have a much different appearance.