Re: Isolating the Computer, ESC, and Distrib Module

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My Stepfather's speculation on the computer... (Stepfather = race-car driver/mechanic does all his own work - keeps many vehicles going). Anyway, he suggested looking for more grounds - and
speculated that maybe the computer isn't getting adequate ground - except via the test-jumper through the test-pin. Well it makes a little sense. Will look for such while fixing the gas and tranny lines tomarrow. Meanwhile, it's been running about 6 hours now - smooth, quiet, clean. Oil is clean, no oil or water leaks. So it's comming along OK. Thanks again NG - for listening, speculating, etc. Elliott
snipped-for-privacy@comcast.net (Elliott) wrote in message

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snipped-for-privacy@comcast.net (Elliott) wrote:

Smart man, your stepfather. Any chance that some of it might rub off?

It makes a lot of sense.

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How about a new marvel approach?
The fuse in question is fed by a fusible link, either on the firewall on a bulkhead connector. Made of a bakelite type material, or on the starter main lug, where the battery plus cable goes.
My bet after you said you juiced the fuse is that, the fusible link is toaster, not connected or broken!
Refinish King

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And YES I'M HAVING A BEER NOW!!!!!
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Drink 12 and then go play on the roof.............................
Doc
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Ran/leaked 10 Gal of gas through it in 12 hours today. Requires the AB diagnostic jumper to run, and it keeps flashing the 12... According to Haynes, the Probable cause is: "... no reference pulses from the distributor are reaching the ECM". That makes good sense why it would shut off within 2 seconds too (w/o the diagnostic jumper). Guess that's something else to look for rather than throwing a new computer at it. Meanwhile, it runs and it can move itself onto the car-hauler for moving. Also, Haynes has the OBD1 pin out on the adjacent page:
A Ground B Diagnostic Terminal C Air (if Used) D Check Engine Light (if Used) E Serial Data F TCC (if used) {what is TCC?} G Fuel pump (if used) H Brake sense speed input M Serial data (4-cyl engine only)
Elliott
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You were so amazed it started that you didn't want to shut it off? WTF is the point of letting it run for 12 hours? Bob
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Probably just run in time, to see if anything was going to break that he missed - as he "rebuilt" the engine. Dunno how many times I've fixed something, just lightly used it - or didn't use all of its functions, and had to take it all apart again when something was wrong. Last thing like that was when I installed a stereo in my 1990 GMC Jimmy.
~KJ~
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Yes the point of running it those hours is break-in for the fresh built engine. You know the 500 miles of 'easy' driving. Plus I get to see if any oil or water leaks develope, cooling, exhaust, etc. It's the first time this vehicle has run in years, and the first I've seen it since I bought it recently. The gas and Tranny Fluid leaks were minor enough to allow it to run - but will get fixed today. And no it wasn't so amazed it started - I was amazed what a PITA it was go get it started and that the computer had to be in debug mode. The 2 second start/shut-down isn't a 'limp home' it a computer induced complete shut-down (nobody suggested that either). Anyone know which wires to check for the pulses from the distributer to the computer? 1 pulse per firing? 6xRPM pulse rate? 12V pulses? Haynes shows 4 whires: WHT, PPL/WHT, TAN/BLK, and BLK/RED. Elliott

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

If you have a scope handy, put it on the purple/wht. It's the reference pulse to the computer from the distributor. blk/red is ground, wht is the signal back to the dist, tan/blk is the timing set/ign bypass. You should get a series of square pulses, 12v, about 50 msecs apart at idle, IIRC. It's 6 per revolution on the six cylinder. You will get a signal since the truck actually runs. Your injectors cant fire without the signal coming in.
Now, if you're ready to actually fix the problem start with the computer. There are battery inputs on terminals B1 and C16, and ignition input on terminal A6. Disconnect the computer, hook up the battery, turn the key on, and make sure you have 12 volts at these terminals. Use a test light to make sure that the wire can actually carry some current and isn't just holding on by a strand or two. grounds on A12, B3, D1, and D6.
BTW, did you fix the orange wire yet? It's the one that brings power in on B1 and C16.
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Crank position sensor:
Or ignition module. But, if it were the ignition module. It would kill the injector pulses too.
Refinish King

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Do you really think this engine has a crank position sensor? I didn't see one, and it has a distributor - so I'm not sure that would do it (can you elaborate - and describe where it would be?). It's not shown on the Haynes schematics either (even for the 92/newer). And I didn't notice one on the bell housing.
The Haynes 92/newer schematic shows the Distributtor pin-out (IC, Ref-Hi, IGN BY, Ref-Lo, I wrote these onto the other schematic too). Anyway, does anybody know the what that means in terms of wave forms?
And on the other-stuff, the 2nd gas line is now new, the gas-tank ground is solid (clamped on) now, and I took it for a ride... Thankfully it shifts ok - though the 4 wheel drive doesn't seem to be working. 4-L goes into a low gear mode, but it didn't seem like I had 4 wheels going up the grassy slope (had to back down).
Of coarse it's gutless w/o getting it into closed loop mode. The 88 was the same way until replacing some of the sensors and the fuel pump.
Elliott

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If it has a distributor,
No crank position sensor.
I might have been the one to suggest the crank position sensor. I work on more front wheel drives than trucks these days.
Refinish King

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Hmmmmmm... John thanks for the pin-out check-points on the computer. Will be checking there soon since I just found a ROM chip for the computer in a bag with other parts (screws and interior clips) on the floor of the truck - so apparently that's been messed with too. I'm wondering if it has a performance chip, no chip, or what. Also, I'm looking to get a small/cheep hand-held type O-scope - My old one broke a few years ago and I've not replaced it. Would sure be nice to have one right now. Elliott
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snipped-for-privacy@comcast.net says...

Use the scope money on a down payment.
Seriously, though, I've got a few scopes, analog and digital. I've actually hooked one up to the truck once, when I was building my father's toy and couldn't get the thing to lean out. You don't need one to diagnose problems on the TBI systems. Stick to the basics: Look for voltage where it should be.
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Yea that's how I've avoided having to buy one this long. Saw a nice scope go for $60 on ebay last night. Wend from $40 to $60 in the last 20 seconds. Elliott
John Alt wrote:

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Progress but not there yet... Hotted the ornge wire (via a piece of that old ornge extension cord). That gets the fuel pumping and it starts - for a moment. Gets up to about 1500 RPM and shuts down. Doesn't seem to be timing related (timing bolt is still loose - tried everything that would make it start). Best I can figure is that the computer is sutting it down for some reason... Would the oil-pressure switch be a possible reason? Should I just short the leads that plug into it? Thanks for the help so far. Elliott
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Hey Elliot, Hope you have a good move to your new place. We'll see you when you get back.
nospam
says...

FP-relay
hooked
few
the
or
for
them
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If your moving to NY then you may as well not bring any of the vehicles your working on. LI does Smog testing on the dyno AND Code scanning. IF any codes show up or you have a smog problem your vehicle fails. This is required BEFORE the car can be registered in NY and you have 30 days from the time you move to register it in NY. They can give you an exemption if it fails BUT only after you spend more than 800.00 to have it repaired and tested again. That is good for one year and then the registration expires. You then have two choices. Scrap the vehicle OR spend enough money to get it to pass. No other options.
--
Steve Williams


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Thanks NoSpam, Steve, The 87 S-10 will be smog-free (once I get the wiring issues fixed and it running in 'closed-loop'). The 96 Sonoma is fine and recently passed in MD. The 95 Saturn may be in trouble. It's fouling 1 plug every 2 weeks or so. I believe it has stuck rings on that cylindar. A prior thread discussed Restore, Greased Lightning, Marvel Mistery oil, and using these to 'clean out' the cylindars. At the time it seemed to work, but since then I've come to the conclusion that the real difference maker was rotating the spark plugs. Compression is only 75lbs on that cylindar too. So in LI that car is depending on the S-10 to be it's backup. With my wife driving that or the Sonoma I will have the opportunity to pull the engine and replace those rings (provided I can find a house or garageg with enough space to do it). On the S-10, the priority needs to be the lights right now, and if fixed a MD set of plates. The computer, etc are questionable but not as high of a priority for getting a plate in MD before I leave. If it gets a plate it becomes easier to move and park wherever it is. And though I'm going there soon, I won't be a resident in the typical 30 days... Will be living in a hotel for a few weeks while shopping for housing. I'm not sure what kind of I-net access I will have during the hotel time (other than work where I won't do usenet). Maybe I can get a cell-phone adapter for the computer - anyone know of such a thing? Last time I tried to find one it wasn't available (made me wonder if it was a homeland security squashed thing). Elliott

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