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ECM repair

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Old 09-28-2017, 05:33 PM   #1
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ECM repair

Hello,

I currently have this thread running in the Electronics forum:
https://www.thirdgen.org/forums/elec...nt-sensor.html

However, I have another question that's specific enough that I think it merits a new thread.

How feasible is it to repair the ECM? A quick summary: car's throwing a code 15, but seems to be outputting 12V instead of 5V reference across the coolant sensor connector - likely to be an issue with the ECM.

Are there PCB layout diagrams anywhere, has anyone else bothered to pull out the printed board and test and replace components?

I'm a bit green when it comes to electronics, but I do have a soldering station, access to eBay and a sense of wide-eyed optimism!

Many thanks for any help of advice!

N
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Old 09-28-2017, 05:44 PM   #2
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Re: ECM repair

You might be able to find a schematic at pcm hacking.net bye searching the service number.
It might look similar to this cts schematic.
http://www.vmeng.com/project-s/elect...7749sheet3.gif
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Old 09-28-2017, 05:55 PM   #3
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Re: ECM repair

Ah, ok. That looked like gibberish at first, but I think I'm starting to understand it!

What's the service number? Is that printed on the ECM casing itself, or is it the part number?

Thanks!
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Old 09-28-2017, 05:59 PM   #4
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Re: ECM repair

There sould be a sticker on the ecm with the service number on it. You can google that number to see if you can find a schematic. Or pop open the case and follow the cts circuit on the pcb.
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Old 09-28-2017, 06:07 PM   #5
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Re: ECM repair

Yeah, I did think that if I just opened the case, then the circuit board is basically its own diagram! I was just hoping some sort of schematic would help me understand the components and the values of the components I'm looking at.

I had a look through pcmhacking.net (didn't take long!) and I don't think I found anything relevant in the US GM ECMs section - thanks for the lead though!
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Old 09-28-2017, 07:12 PM   #6
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Re: ECM repair

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Old 09-29-2017, 08:55 AM   #7
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Re: ECM repair

Ah, hmm... they are pretty cheap on eBay.

My 'nuclear' option was to get a reconditioned one from Rockauto. I can get that delivered for about 115 including shipping and taxes, which is probably worth it for the extra 40 over that used one once I've taken the shipping, taxes, fees and the long wait into account! It does look like there are cheaper ones online though, with commensurate increase in risk I guess...

Rockauto has my ECM No. as 1226865. Does it make a difference if it's manual or automatic? I'll dig out my shop manual when I get home and see if I can find the correct part number.

I can see why few people bother with repair when you can pick up another used one for less than $40!

Cheers,

N
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Old 09-29-2017, 01:15 PM   #8
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Re: ECM repair

If the service number is the same that's the correct ecm. It doesn't matter if it's auto or manual just use your old computer chip.
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Old 09-29-2017, 06:35 PM   #9
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Re: ECM repair

Ok,

I've dug around in the parts catalogue and found the following numbers for the L69:
1984: 1226455
1985: 1226865
1986: 1227169
I guess I'd better see if I get a chance to dig my own out over the weekend. Is there any substantial difference between these, or is the difference primarily in the PROM chip?

Cheers for helping me out with this!

N
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Old 09-29-2017, 06:38 PM   #10
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Re: ECM repair

If you post the letters off the prom I can identify the ecm. Each ecm will have letters on there prom they are ecm specific and can't be interchanged.
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Old 10-09-2017, 04:19 PM   #11
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Re: ECM repair

Well, that took some time to get round to!

Ok, there are quite a few numbers on the PROM chip. I can't quite see them all as I broke the plastic clip thing trying to get it off, so left it installed

However, there is the number '4303', which seems similar to the number 4302 which is mentioned on Rockauto for the PROM spec. It also says 'DELCO 06630'.

It also has 'Malaysia 980' and '71691'.

​Ah, I forgot to mention the sticker on the ECM case (and on one of the chips inside) that read '8759445'.

There's also a big sticker with a barcode on top of the calpak (memcal??) which read '628041121436139'.

Is that any help?

I tried tracing circuit no. 3 from it's point on the connector, but it wiggled about a short while before diving into the board where I couldn't trace it any further. It didn't seem very straightforward to remove the board from the metal case, so I didn't try to get it out so I could follow it from the underneath. From the look of it, trying to fix this without a circuit diagram is a bit of a non-starter. It's frustrating as if I could tell what components I needed I could probably fix it for about 50p!

Cheers,

ND

Last edited by ndndndnd; 10-11-2017 at 03:41 AM.
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Old 10-11-2017, 09:21 AM   #12
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Re: ECM repair

Aha, I just found this by randomly googling some of the numbers on the chips:

http://www.ag.auburn.edu/~parmega/efi/inside7747.htm

It looks like theres's quite a bit of cross-over between this ECM and the 1226865 (I think!) I've got. That diagram does indicate the location of the 5V sensor regulators, and that it's a 5089 chip. I can't see it, either in that diagram or in my own (it's back in the car), so I can't identify it positively from googling.

Interesting...
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Old 10-12-2017, 07:04 PM   #13
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Re: ECM repair

Is this the information you were looking for ? Gm part number 16044302

https://www.gmpartsgiant.com/parts/g...-16044302.html

Last edited by Tuned Performance; 10-12-2017 at 07:07 PM.
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Old 10-14-2017, 04:38 PM   #14
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Re: ECM repair

Ah, thanks for the link! That led me to an alternative part number that gave me a few more options should I just go and change out the ECM.

I did find a few references to a guy called Ludis Langens who seemed to have a website holding all sorts of ECM and GM OBD1 data which might have held more data on the chips inside the ECM, but his website seems defunct, as does a mirror site run by a company called Xtratorq. Pity as it looks like it might have held the data I need to repair the ECM.

Does anyone have idea where all his information might have gone?

Cheers!

N
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Old 10-26-2017, 04:15 AM   #15
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Re: ECM repair

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Originally Posted by ndndndnd View Post
Ah, thanks for the link! That led me to an alternative part number that gave me a few more options should I just go and change out the ECM.

I did find a few references to a guy called Ludis Langens who seemed to have a website holding all sorts of ECM and GM OBD1 data which might have held more data on the chips inside the ECM, but his website seems defunct, as does a mirror site run by a company called Xtratorq. Pity as it looks like it might have held the data I need to repair the ECM.

Does anyone have idea where all his information might have gone?

Cheers!

N
The Ludis site has been down for awhile. Craig Moates had a great little site with a ton of ECM information and dumps and stuff but I don't see it anymore. I think someone was mirroring the site. You might want to ask him if he has a cached copy of the website somewhere. Maybe we can find a free hosting site to mirror it again and keep it going. There's also a possibly that JT will allow us to create a thread with the info on that site on here and keep it in the fam.
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Old 10-29-2017, 07:53 AM   #16
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Re: ECM repair

I purchased an A1-cardone refurbished ECM from Rockauto a few days ago, it's currently sitting in a shipping container in California awaiting being shipped to the UK!

Can Craig Moates be contacted through this site? Who's JT? It would be interesting to get this information back up in the public domain as ECM's are likely to become rarer in working order as the years go by, and possibly more in demand as people start to want these cars in stock form as classic cars. Would this information even be the basis for recreating the ECM using a Raspberry Pi or similar? I'll admit I know very little about these things!

Cheers, ND
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Old 10-30-2017, 06:27 PM   #17
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Re: ECM repair

Quote:
Originally Posted by ndndndnd View Post
I purchased an A1-cardone refurbished ECM from Rockauto a few days ago, it's currently sitting in a shipping container in California awaiting being shipped to the UK!

Can Craig Moates be contacted through this site? Who's JT? It would be interesting to get this information back up in the public domain as ECM's are likely to become rarer in working order as the years go by, and possibly more in demand as people start to want these cars in stock form as classic cars. Would this information even be the basis for recreating the ECM using a Raspberry Pi or similar? I'll admit I know very little about these things!

Cheers, ND
Craig is a member on here and was really active before but I don't know how active he is anymore. You could try to message him here or on Moates.net where he sells his goodies. JT is the webmaster on this site.
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