When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 1992, base model with about 150k miles. Car sat for a couple of months while I troubleshot “no start”. Determined it was the opti. I replaced it and also the water pump.
Car runs good now, but after about 15-20 minutes, I get a SES light, code 26. I have a copy of the FSM (2 vol red books) and went through the diagnostic steps using my multimeter (I don’t have a $1000 for a used Tech 1). This involved checking the Purge solenoid, EGR solenoid, ESV solenoid, and the smog pump. I changed the bad Purge solenoid, and the smog pump. I also replaced the PVC valve. I went through the diagnostics steps again, and all tested good. The last step was to replace the ECM.
I checked O’Reilly, AutoZone, Advanced Auto Parts, Napa, Rockauto, and a few other sites. Seems reman ECMs or ones that are pulled from donor cars for my year are almost non-existent. The ones I did find are about $1000. Places that will repair my ECM run about $500. I’m pretty sure I’m going to go with repairing my ECM. But before I do, I was wondering if anyone has any other troubleshooting suggestions?
If nothing else to look at, does anyone have a recommendation for a place to have mine repaired? I did search through this forum, but didn’t find anything recent. I did see an old thread that mentioned SIA Electronics in Illinois, but a little wary of sending my “rare” part and a check halfway across the US.
Yes, I did see that post. I don't have a Tech2, but was able to duplicate the testing with my multimeter. That second picture is from the FSM which is what I followed. On the left-bottom of that page, it points you to the "Diagnostics Aid". That section has you move the wires/harness to see if you have an intermittent error. I don't think my issues is intermittent, since it happens every time. The last step is to replace the ECM.
By the way, I'm clearing the codes each time by disconnecting the battery for several days.
So you have manually tested the 3 solenoids and the relay by grounding the side which is normally connected to the ECM ? and they all switch properly (by hearing them)?
Extract from my 93 MY FSM
The Tech tool or equivalent would have been useful to trigger manually the ECM concerned inputs and see if they switch properly by placing a defined load / resistance on the ECM, as well as measure the amount of current drown by the driver..
Note that the ECM is by design probably not capable to fully bring the B sides of solenoids / relays to pure 0V, usually around 0.4V, depending on what chip is used as Quad Driver.
But I understand that this is quite an expensive piece of (old) tech.
From I what read in the post I sent (and other posts about the 1992 CCM), they seem to be known for failing...I don't know what to say, if other forum members want to give their opinion before you send your ECM out for reflow or repair...?
Yes, I grounded each of those 4 using a circuit tester. I tested several times and could hear the 3 solenoids and the 1 relay on the air pump "click" and my circuit test light up.
On Step 2 of this diagram, my multimeter gave me the following readings: A7: 0.18, A8: 0.30, A2: 0.25, and A1: 0.45. Though they're all different, they're less then 0.75 and not 0, so I'm assuming I'm good. I could also hear the solenoids and relay "click".
Yes, that looks good to me. It is definitely less than 0.75A as you mentionned.
Is the harness properly plugged into the ECM. Another forum member just had an issue with the speed sensor, the harness was simply not properly seating in ECM yellow connectors. It can happen due to the little gasket.
However, based on the experience of the other 1992 C4 owners, the cause of failure has a high probability to be related to the driver itself.
To be checked with this famous SIA company how much they charge as of today...These 1992 ECM must be a fruitful business...
Or maybe you're a skilled technician and can open the ECM by yourself, identify the concerned chip, reflow the connections or change the chip (if it has an easy to solder package, like DIP type)
That ECM connector looks good. No bent pins. One thing I didn't think of, but will do this week is to spray the pins with some electronic cleaner spray. If I can find my mini files, I'll gently clean both ends.
Ya, I did see a couple of ECMs on eBay, 800-1000. Too much for me. That's why I'm leaning towards having mine repaired. I did see some others mention SIA. Its $450.00 to repair, $89 if it test good. But they really need to fix their website. No clear direction on how to submit information and payment. I called and talked to someone and I'm send info and a check with my unit. I guess I'm kind of wary of sending my "rare" unit and a check half way across the US. No easy recourse of things go wrong. But if other members have had a good experience with them, I might be less hesitate.
I did think of opening it and seeing if I could repair it. But I would consider myself as less than a newbie when it comes to soldering. If it was a cheapy unit like a clock radio, I wouldn't hesitate to try. But not on my ECM.
Oh, someone did mention G7 Electronics, but no opinions. So if anyone knows of a good repair place, I'd be most appreciative.
I'd use contact spray instead of PCB cleaner, or isopropyl alcohol. PCB cleaner solutions are meant to remove flux spatter after soldering.
Do not attempt to file / scratch ECM pins, they are manufactured with specific tolerances to ensure electrical contact with the mating part, they also have extra plating to ensure the proper contact (and material compatibility with the metal contacts). If you start scratching them, the contact plating is gone, increasing your chances get really bad electrical contacts. Same remark if you plan to clean up the harness connectors.
if the reman company states "sorry can't be repaired" after analysis, ask to get it back anyway (you should make it clear before signing up anything!), we could then try to figure something out, nothing to loose, or eventually send it somewhere else.
If you've never experienced soldering, forget it, you will cause more damages than what we might have at the moment. You also need decent equipment to perform such repair.
Try to get quotes from other reman company to lower down the reman cost. Other forum member should also share their reman experiences...
Thanks for the warning. I did get quotes from other companies. But I'd feel more comfortable if I could get some recommendations. I pretty much take yelp and any other on-line reviews with a grain of salt. At this point, I'll wait to see if anyone chines in with ECM repair place recommendations. I don't know if its allowed here, but do you know of any other forums I can post my issue?
Use SIA in Illinois. I recently interacted with them on behalf of another member in Germany that was having trouble with his 92's ECMs. SIA eventually solved his issue. I've used SIA for other components, and they were fair, if not exactly speedy. I've never seen a horror story re SIA on here, but there have been with other vendors. I can't remember the name, but there's an outfit in Florida that is a total scam. Do not use them.
I don't know if its allowed here, but do you know of any other forums I can post my issue?
I think of two other possibilities to get some information about reman :
https://www.gearhead-efi.com/ which is litterally a PCM / ECM forum, sign up, do a quick introduction of yourself, create a topic.
Since I do not own an LT1 C4 but an LT5 C4 (ZR-1), our community deals directly with our ZR-1 expert when it comes to any tricky issues including ECM problems (your ECM and our ECM have design "similarities"). You can send an email to Marc Haibeck (mhaibeckz@gmail.com) from http://www.zr1specialist.com/ explaining your situation. I'm not sure if he deals a lot with LT1 but an ECM remains an ECM. He's based in Illinois, so may works directly with SIA...who knows.
Thanks for the info on the Tech2. $400 is a little out of my budget. More of a "nice to have" then a "need". But it should would make diagnosing much easier.
RSLyrick,
I just registered with gearhead. Waiting for approval. I'll email Mark once I draft it.
ECM help
