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Haunted 92 Yukon

Blaze

Blaze

1/2 ton status
Joined
Aug 28, 2000
Posts
3,285
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Location
Raleigh, NC
Strangest thing happened on the way to work today. I'm rolling down the highway at about 75, going fine. Hit a spot that they started paving and BOOM /forums/images/graemlins/shocked.gif, whack into the bump that they just paved and the truck immediately dies /forums/images/graemlins/angryfire.gif. No power at all. Roll over to the shoulder, put it in park, fire it back up, and drive the next 20 minutes to work. Very odd to me, never had this happen to one of my cars before. It seems like it shook something loose when I hit that bump /forums/images/graemlins/mad.gif. My exhaust is loose because of a bent hanger, could that have caused anything? Help me here, I drive the truck over 70 miles a day! /forums/images/graemlins/1zhelp.gif
 
Check you battery cables. My 96 GMC was doing something like that and it was all because a connection at the terminal was bad. Only mine was so bad that sometimes it wouldn't even start.
 
Well, I cleaned and checked the connections and it worked for a litt,e but now it is really bad. I think my battery might just really suck and I need another one. I'm going to go put one in at lunch and see if that works. It better work. I have a 35 minute commute home, don't want to break down on I40.
 
check your alternator, ignition and battery, and all connections associated with each.

you might have short somewhere in ignition thats causing troouble.
 
I replaced the battery, checked all the connections, had a system check at Napa, but it still died this morning on the way to work. I put it in neutral and fire it back up and keep on driving. It seems to only do it when it is cold, never does it on the way home from work. Man, I hate electrical troubleshooting. PLEASE HELP ME! /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif
 
I got a code 32 and a code 42. The code 32 is the EGR valve, and I think the code 42 is the electronic spark timing. What exactly is the Electronic Spark Timing and how do I fix it? My truck is going insane! /forums/images/graemlins/crazy.gif
 
i searched the ORC archives and here's a couple responses:

<font color="green"> It means that one of the wires from the Engine Control Module (ECM) to the ignition module has been broken or cut. It also means that maybe one of the ECM wires to the ignition module has been rubbing off wire insulation on metal and the bare copper wire is touching body or engine metal. It's a simple thing to figure out if you know how to read the ECM wiring diagram, and know how to use an Ohm meter. Maybe you just did some work under the hood, and might have pinched one of the ignition module wires on a bracket or something.
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<font color="blue"> I'm not positive about the wire color codes for your vehicle. But usually the the ECM has four wires from the distributor ignition module. Usually the Electronic Spark Timing (EST) Timing Signal is a white wire. The other ECM wire from the ignition module is the By-Pass Signal and usually is a tan wire with a black stripe. The ground wire from the distributor ignition module is usually black with a red stripe. The RPM reference wire is usually purple wire with a white stripe.

When the ECM senses an engine speed of about 400 RPM from the distributor ignition module RPM reference (usually a purple wire with a white stripe), the ECM applies 5 volts to the distributor ignition module By-Pass circuit to switch the ignition timing from the distributor ignition module to the ECM. An open or shorted By-Pass circuit will cause the distributor ignition module to operate the engine in back up ignition timing mode. Code 42 will be set and "SERVICE ENGINE SOON" SES light will come on if the open or shorted condition exists the next time the vehicle is started.

I don't have a wiring diagram for your truck. If your truck was here in my garage I'd look it see if the 5 volts was on the By-Pass Signal wire once the engine started and was running more than 400 RPM's. If the ECM showed the 5 volts, then I'd use an Ohm meter to check the By-Pass Signal wire from the ECM to the distributor ignition module. If the By-Pass Signal wire checked good, I'd install a known good distributor ignition module and see if the fault went away. If the known good ignition module did not fix the problem, Id take out a bank loan or use my VISA and go to a GM dealership to fix the problem.
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I appreciate the info. I have a broken exhaust hanger, maybe the exhaust moving around knocked something loose. I'll have to get in there and check it out. You think it'll cost that much to take it to the dealership? I don't know any good mechanics in my area, so I was thinking of taking it there. Man, this is pissing me off!
 
Dealership had no idea. I put a new ECM in it myself and it fixed the problem.
 
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