Desperately needing help

[boydchr]

Sorry if something similar has already been posted but I haven't found a solution that works. My 2004 Silverado 1500 LS, 5.3L Vortec is giving me all kinds of fits. Would be happy to elaborate the long story but going for the short to start with.

 

I have been having problems with hitting the key and nothing but a dash reset; this has been intermittent since the first of the year and usually would clear itself up. When this happens I get all kinds of weird lights and messages but no codes. It would usually clear itself up within a couple of days then I could drive for a few weeks with no problems. I did notice that sometimes when it happened the blower was left on when trying to start it but didn't seem to be tied to weather. The two worst instances, one a snow storm and the other 80+ degrees.

 

Two weeks ago I forgot to turn the air off and when I started the truck to go home the check engine light was on, the ABS light was on and the brake light was on; I also noticed that the air was still on but the blower wasn't working. The truck would barely move itself. I turned everything off and started it again but had the same symptoms. It barely limped home and started the no attempt to start problem again. I read the codes and had 740, 753, 758, 785 and 2761. Did some research and found that if you get all these codes the most common fix was the ignition switch and this was confirmed by a mechanic after he looked it up in his resources. Logically everything made since that the problem was most likely the ignition switch, it wasn't unless O'Reilly's sold me a bad switch.

 

Here are some things I have tried:

• The battery is a year old and has been checked but I think there still may be a problem with it. I had to do a relearn on the security because I replaced the PCM so I hooked a charger up as suggested. After the relearn the key would bump the motor but that was it. I found if I held the key it would bump, wait a few seconds then bump again and repeat the cycle. I left the charger on and over time the cycle would shorten. Finally I went out and the engine turned over like normal, started and the charger indicated the battery had a full charge.
• I checked all the fuses and relays
• I replaced the starter a couple of months ago thinking it might of had a dead spot, it failed with the new starter the same day I replaced it.
• I had the bright idea of running a wire from the S post of the starter to the top of the motor to attach a remote switch. When the no attempt to start problem occurred I used a remote switch and it would start and immediately shut off (theft deterrent I suppose) but if I used the remote switch and key switch at the same time it would start but the truck would not move so I expect the transmission was not being energized.
• I replaced the ignition switch, I assume I have it in correctly because the switch seems to work. I did try moving the gear a notch or two both directions and got less than desirable results.
• I replaced the PCM last night and did the security relearn; I get the same results with the new PCM as I do the old. I have swapped them out a couple of times today with no difference and now they both show the same transmission codes.

Right now the truck will start with just the key but will not move. The check engine light is on with the codes being the transmission codes listed above. The ABS light is on and the Brake light is on (the parking brake is not set) and the heat/air blower does not work. Is there another ?CM module that could be causing these problems?

 

Aren't you glad I didn't go into the long story?

 

Thanks

 

Chris

[BlackZ71Silverado]

Does the truck do this when it's wet, after it rains, is washed, damp outside?

 

 

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[06pirate]

If you haven't yet, you might pull off the fuse box and look at the wiring under it. A couple of years I had a mouse attack, those little bastards ate the insulation off all the wires, and there were a few strands that had touched each other intermittently, causing all sorts of weird problems. I spent a while replacing and splicing wires.

 

pics below

[boydchr]

It has done it in wet, dry, snow, ice, cold, warm and couldn't ask for a nicer day type of weather.

 

I haven't looked under the fuse box yet, haven't looked close enough at it to see how to pull it off yet either. Don't think its mice or rats, our rodent problem is squirrel and rabbit; I have "project" cars that have sat for years and the only animal problem has been a litter of stray kittens. Plus the hood is up on the truck at least once a week; nursing a blown head gasket for years now and I put oil and water in it more often than I do gas.

 

I have been thinking along the lines of a short. I did read some posts somewhere about problems with the blower and I have had the symptoms for several years but the truck is over 10 years old and the recall I read about had a time limit of the first of 10 years or 150k miles. I did notice several times that when the problem occurred the blower had been left on and it was left on for this round of trouble; now the blower doesn't work at all and the truck hasn't been drivable for two+ weeks. Could a short in the blower wiring cause the ABS and Brake warning lights to stay on and not allow the transmission electronics to energize? I have noticed that when attaching the ground to the battery it sparks more than I expect but I just figured this is from some of the electronics that normally stay energized. Something I found odd, my wife has been in the truck a couple of times when I worked on it while stranded in a store parking lot, she said when I reconnect the battery all the gauges jump and the dash lights flash and the key is off.

 

Here is an example of my frustration: In February we had a snow storm on Thursday and the truck decided it didn't want to go home. I had my son come to jump it and ended up leaving it at work. On Saturday I tried jumping it again and ended up taking the battery home to charge it. Went back to work on Monday and put the battery in and tried everything I could think of for 30 minutes then called a tow truck. The tow truck driver tried every thing he could think of for 30 minutes and then hooked up a cable to pull it out of the parking spot. When he got in to put it in neutral he tried to start it again and it started so I drove it home and didn't have any more problems for several weeks.

[chevydad8]

could it be the neutral safety switch, I know that doesn't explain the blower not working, are you able to turn the key on to accessory and get the blower and radio n such to turn on

[Black02Silverado]

I would start with pulling all your ground wires off the frame, body and engine, clean up the contact area and put back on. It is amazing how a bad ground can cause all kinds of issues and since this is over 10 years old they could be corroded.

[asilverblazer]

I agree with the grounding problem. You could try using jumper cables as temporary grounds to test it.

[boydchr]

Sorry, I wasn't receiving any replies so I abandoned this post and moved over to Chevrolet Forums try this link to see what has been posted there: http://chevroletforum.com/forum/silverado-fullsize-pick-ups-21/electrical-problem-73296/#post304306

 

I checked and cleaned all grounds I could get to plus I tried running temporary grounds between different points and no it is not the neutral safety switch either. Oh, I did put my original PCM back in and sent the reconditioned one back for a refund; they only charged me $40 for restocking which was better than eating the whole $200.

 

In www.alldatadiy.com I found Technical Bulletin 09-06-04-004D which described the intermittent problems I was having. I did a lot of electrical research and probing, could probably come close to passing the ASE Electrical Certification exam now.

 

With the help of Bern on the Chevrolet Forum I am 98% sure we have pinpointed the problem as being on circuit 142 and specifically located at the B12 terminal of the C1 connector on the under hood fuse block. That terminal was badly burnt and melted into the connector (there is a picture posted at the link above). I am about 80% sure the root cause was the blower resistor which I have also replaced; the blower had been giving me intermittent problems for over a year. My dad's '05 Sierra that I am driving right now is showing some of the same blower symptoms I was getting so I need to get with him about changing his blower resister.

 

The local Chevy dealer did not have a listing for that connector and tried selling me a fuse block for $520; the actual part that he should have tried selling was the wire harness but I wouldn't have bought that either. One salvage yard said I could go clip one off but they would charge me $125 for the entire harness. At a "Parts-U-Pull" salvage yard, I got two of these connectors for a total of $5.19. I will be installing one of these connectors tonight and hopefully will be driving my own truck for the first time in almost two months.

[boydchr]

The problem was actually with the plastic connector being melted. The B12 terminal broke free and fell out on its own and all it needed was a little more cleaning, a new home to live in and a little dielectric grease. Put everything back together, voltages returned to normal and I took it for a drive.

 

Thank you to everyone who posted and a special thanks to Bern from the Chevrolet Forum who pointed me in the right direction.