Isolating the Computer, ESC, and Distrib Module (continued)

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Tonight I pulled out the computer, and it didn't have any chip in it. I had figured the prior owner would have had a reason to pull the chip and leave it in a bag on the flor
(performance chip or somehting), but nope, just an empty socket. God knows why the prior owner would have pulled the chip.
I installed the chip, and I no longer need: 1) the hot to the ornge wire (fuel pump power) 2) The OBD1 debug jumper (A&B). 3) The hose-clamp that increased the idle a little.
With the jumper and engine not running, the computer flashes codes (12,23,34,41,42). For NG cretique and ideas, my interpretation of these by reading Haynes is: 12 - since it goes onto other codes, this just starts the sequence of reading codes. 23 - MAT low temp indication (where it this one?) 34 - Vacuum sensor or MAP sensor (are these the same or is there a seperate vac sensor - I probably do have vacuum issues) 41 - {not in my book, anybody know what it is?} 42 - EST (Electronic Sparc Timing) - "Electronic spark timing bypass circuit or EST circuit is grounded or open. A malfunction ing HEI module can cause this code" (? is this pointing at the distributor-module?) {The last I checked timing it was about 8 degrees BTC - before I tightened the bolt - guessing it's between 5 & 20 degrees now - will go check as I post}.
And yea I'm still trying to figure out what to do with this truck (keep/sell/junk). Of coarse it's getting closer to something i could sell with a clear concience. And yea the prior owner was dishonest - I wouldn't sell something like what I bought. I guess I bought this from the kind of owner that you guys often imagine me to be - cludge artist, etc - but at least I'm honest about my cludges and wouldn't try to hide them from a buyer.
Ideas and suggestions are appreciated - though please be patient as I do tend to jumper and cludge my own test cases.
Thanks, Elliott

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After running for an hour the codes are now 12, 15, 23. Having dinner - will read later - thanks in advance. Elliott
Elliott wrote:

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http://www.syty.org/old/d&e.html#chk
Click on each of the codes to gain more info on them. This page is good. Read all of it, then go on to the codes. The page is designed around the Sy/Ty family of S10's (4.3), so some info may or may not apply to your engine
Low readings on these circuits (coolant and MAT) are often caused by corrosion at the connector.
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Thanks John, that's allot more info than Haynes - will appreciate that page for a long time. I've traced through the vac diagram - need some more hose, but I think I have it correct (though leaky connections). I found a pair of wires that appear to go to a smashed sensor at the front of the driverside head. Shorting them together pegs the temp gage, and open zeros it - but the colors are green and dark blue (or maybe black), rather the the blk & yel that are on the water-manifold temp sensor. I'm guessing the sensor adjacent to the water manifold is the sensor in the schematics and the other one is just for the the gage. After correcting the vac lines, I got some of the codes back. I now have 12,23,34, 41. Reading the link now. Elliott
John Alt wrote:

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A diagnostic circuit check should have revealed at least a code 51 (prom error) and lead you directly to the problem.

IIRC, this is an 87 S-10 with a TBI 2.8 liter V-6 my answers will be addressed towards this as being the model, year and engine...

Not true. Code 12 means that the ECM is not receiving distributor reference pulses from the ignition module. Since the engine is not running, this is a normal condition. Since code 12 is the lowest numerically possible, it shows up first. In a rather crude way, it does show a minimal ability that the computers diagnostic routines are somewhat functional.

The 2.8 didn't use a MAT sensor. The 4 cylinder 2.5 did. Possible causes are; wrong computer, wrong PROM, defective computer, defective PROM. Can't see this occurring any other way.

Yours has only a MAP sensor. make certain that it's plugged in and that the vacuum line is connected to a manifold vacuum source and that vacuum source is not plugged with gunk.

Code 41 is not valid for this application. Code 41 is a valid code in certain other GM applications but they wouldn't apply to this particular vehicle due to components it never came with (i.e., a cam position sensor).

Code 42 is the normal trouble code that would set if the set timing connector was opened as in when the base ignition timing was being set. Check the set timing connector first.

The ECM doesn't know where the timing is set.

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Thanks Neal. I'm nore suspicious of my computer after reading your comments. After correcting the vac lines, I now have 12,23,34, and 41. Since 23 and 41 should be impossilbe (interpreting your comments) for this engine I'm wondering if the computer is even the right computer for this truck. After what I've experienced with this vehicle I wouldn't be surprised. When I price-checked the computer at the J-yard they asked me to tell them tha numbers on the old one because they couldn't determine otherwise. Well i wonder if the prior owner parts this thing from a few different sources. The web page that John referenced suggests jumpering pins B&C of the MAP sensor to isolate the MAP sensor. That and re-checking the vac to it I can do tomarrow. Meanwhile, it runs better, but the codes are as much BS as helpful - and my best guess is what you said - the computer is probably the wrong computer for this truck. Thank again, Elliott
Neil Nelson wrote:

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Ok I just tried again...
disconnected the battery, jumpered pins B&C of the MAP sensor, reconnected battery, started for 10 seconds (got a light in 5), shut off, jumpered, and read out codes 12 & 23.
23. a non existant MAT per Neil's earlier response - hmmm.
Restarted and ran for about 30 seconds, shut off, jumpered, and read 12, 23, 34, 41, and 42.
34. a jumped-out MAP still generates a code - hmmmm. 41. another non existant (cam posn) per Neil's post - hmmmm. 42. EST - (or timing connector per Neil's comment). Where is the timing connector? My timing reads 16 degrees with a light but I don't know how to bypass via a connector. My impression is that I should jumper something in a connector, and set the timing to about 8 degrees (true? accurate? - no stickers to provide data and haynes references stickers). Will need to let it cool before adjusting the timing since I tightened down the distributor bolt yesterday.
Ideas? Computer fried? Wrong computer?
Thanks, Elliott
Elliott wrote:

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either have the wrong PROM or a bad computer, yet you continue to troubleshoot crap. The codes are meaningless until we know the computer has the sensors it expects on the terminals. On the computer is a 7 digit number. IIRC, for your truck, it is supposed to be 1227747. I posted days ago (March 31) and asked you what it was. Give us that number. There are other numbers that work correctly in that application. Stop now before you fry something. Not all the terminals have current protection on them. Some like the EGR and TCC terminals can push amps and can fry something if it's the wrong computer. The pinouts were different on some car computers. If the computer number is good, you can get by with a PROM. So close the hood and wait till you've got the right computer.
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"John Alt" wrote

I was thinking...."just close the hood".
Ian
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I'd call a wrecking yard and see what they have in the way of a tow truck. B
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says...

'When you want to get out of a hole, step one is to stop digging' seems appropriate here...............
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Thanks guys. The hood is closed. Will share the number on the PCM when I get home. Thanks John for reminding me what it should be. Meanwhile, its looking more and more like it's going to a junk yard all the time. I have an old Florida plate I can put on it while living at the hotel in NY (for sitting, not for driving), but if I have trouble with that it will be the end. About the only other thing that is probably worth doing is looking for cut ground wires near the PCM. I may put it up on ebay if I can navigate being a seller easy enough. Elliott
says...

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snipped-for-privacy@comcast.net says...

undoubtedly never will. I've dealt with them enough to know they are evil. But, in that model year, that is about the only number that was used on trucks and vans. There are several others that will work.
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The magic number is: 1227148. John's reference was: 1227747. hhhhhhmmmmmmmmmm. Maybe I can come up with a better match over the weekend since I sure haven't come up with a way to get rid of the truck. Thanks John, that explains allot. Someone mentioned models from other vehicles, etc. Since I may get a chance to go to Gary's U Pull It on saturday, does anybody have cross-reference data (other vehicles, computer #s)??? If so, this truck is: 1987, S-10, 2.8LV6, TBI, AutoTrans, A/C, 4x4, pwr win, cruise, full gages, etc. Looks like a coupter will run $25 if I take this one with me. And yes I will be looking for bad grounds while removing it. Thanks again NG! Elliott PS: shameless plug for Gary's: http://garysupullit.com/partspricelist.htm
John Alt wrote:

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Hold your horses. I said I wasn't sure. Turns out your looking for a 1227429
At least according to these guys. Someone with a better reference source might want to double check this
http://www.cruzers.com/~ludis/c3xref.html#1227148
Get the right computer and PROM. It has to be for a 2.8 automatic
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Thanks! Gary's may have a cross reference too. Do you know what they mean by the Mempack ID? I have the rest of the numbers from the computer, and the chip itself has a "0588". Elliott
John Alt wrote:

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Jesus, Mary and Joseph..........just go down to AutoZone and get the CORRECT one, put the one that's in your truck in the box and turn it in for core charge.....
The AutoZone sales drones don't KNOW or CARE that it's not 'the same kind' that they sold you
WHY do you INSIST on making EVERY DAMNED THING so much harder than it really is ?????
says...

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TranSurgeon, Bacause I didn't imagine AZ would sell aftermarket computers. Thanks for pointing out an easier source than trying to find one in a J-yard. Thanks, Elliott
TranSurgeon wrote:

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He'll need a prom after that - how do I know! Spent like $90 on the 'computer' and needed to use my old prom. Did not like that one little bit. Especially since it just turned into a power supply problem! Then on the other hand, when I got it back he had removed just the right fuse so the truck would START but nothing else worked really. No gauges - no alternator - Didn't notice anything wrong till about 2 days after when my gas gauge wasn't going down....
~KJ~
says...

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you have GOT to be joking! a/m computers are JUNK!
Re: Isolating the Computer, ESC, and Distrib Module (continued) Group: alt.autos.4x4.chevy-trucks Date: Thu, Apr 8, 2004, 10:35pm (EDT+4) From: snipped-for-privacy@mchsi.com (TranSurgeon) Jesus, Mary and Joseph..........just go down to AutoZone and get the CORRECT one, put the one that's in your truck in the box and turn it in for core charge..... The AutoZone sales drones don't KNOW or CARE that it's not 'the same kind' that they sold you WHY do you INSIST on making EVERY DAMNED THING so much harder than it really is ?????
says... The magic number is: 1227148. John's reference was: 1227747. hhhhhhmmmmmmmmmm. Maybe I can come up with a better match over the weekend since I sure haven't come up with a way to get rid of the truck. Thanks John, that explains allot. Someone mentioned models from other vehicles, etc. Since I may get a chance to go to Gary's U Pull It on saturday, does anybody have cross-reference data (other vehicles, computer #s)??? If so, this truck is: 1987, S-10, 2.8LV6, TBI, AutoTrans, A/C, 4x4, pwr win, cruise, full gages, etc. Hold your horses. I said I wasn't sure. Turns out your looking for a 1227429 At least according to these guys. Someone with a better reference source might want to double check this http://www.cruzers.com/~ludis/c3xref.html#1227148 Get the right computer and PROM. It has to be for a 2.8 automatic
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