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Chevy S10 - GMC S15 and Sonoma Electrical Problems



  • I have a 99 chevy s10 and the last few days I have been having problems with my dashlights, gauges and power locks. I was driving and my gauges flickered and my cd player quit and my clock reset. Tonight when I started it, my parking light came on for a bit and when I got out, my interior light wouldn't come on and my power locks quit. Help! I'm a girl and I don't know much bout electrical stuff.
  • Hi Alisha0218. the first thing i would check is the fuse, the fuse block is on the left end of the dash. If the fuse is ok, make sure you don`t have a tail light bulb burned out, i know that probably sounds strange but they are tied together,if not then it sounds like you have a short in your dash light moduel, which is located under the knee panel, wrapt up in foam & tape it is not right out in the open & does`t look like a moduel it is actualy a printed circuit. i wish you luck, mags
  • I have a 1995 Sonoma, 2.2l 4cyl, Manual trans, 2WD that I am having trouble starting. Initially I had a problem when driving that I would lose all power and the engine would die. I would nurse it to the side of the road and let it sit for a few seconds and it would start back up, as long as my dash lights came on (if they didn't, it would not start). I found that the battery cable to the starter was loose and tightened it. I had no problems for about a month or so.

    Last night, it did the same thing. It started back up and ran fine, but when I got it to my house it will no longer start. Today I checked the starter wires and they were tight. I removed the starter and had it and the battery tested, both were fine. I replaced the starter cable to the battery. I conducted continuity tests on all wires leading from the starter, alternator and into the dash and all seems fine.

    The current symptoms: it will turn over fine, but will not start. The dash lights come on very dim (barely able to see) except for the seatbelt warning light, which comes on bright. All accessories work fine. It has OBD-II, but I cannot find a scanner that will read it (I guess the dealer will have to do it at some point). Any ideas?
  • gonogogonogo Posts: 879
    Check out the ignition switch, it is a known problem.
  • This may sound a little dumb, but how do I check out the ignition switch? I am mechanically inclined and know how to test for connectivity, but that just about reaches my electrical abilities. Thanks.
  • gonogogonogo Posts: 879
    Well it is best to have a wiring schematic, you need to know if proper volts and amps are coming out. A test light is best.
    If you are at a dead end you could just change it but I like to be sure, hate replacing good parts.
  • Hello,

    I see there are a lot of similar problems out there, but I was hoping someone had the same as mine.

    :sick: I have a 94 GMC Sonoma 2WD with the 4.3L V6. The other night all of a sudden the rear parking/running lights just stopped working. :sick:

    The things that aren't working are the license plate lights and the running/tail lights. The bulbs themselves work fine when I hit the breaks, and for the blinkers. The front running lights also work fine, as do the head lights.

    The fog lights aren't working but I think it is because the bulbs are burnt out, but the toggle switch works and lights up.

    I have checked the fuses inside the truck, and the bulbs. They all seem to work. The front running lights are a little gimmicky, some times I have to turn on the head lights or the fog lights to turn on the parking/running lights, but the front ones work fine.

    Does anyone have any ideas or has solved the same or similar problem??

    Someone told me for those models there was a seperate fuse/ fuse box for trailer wiring, and that if it popped out that it would pretty much cover what is going on.

    Any ideas please help!! Thank you!
  • You were correct, it was the ignition switch. When this issue first started that was my first thought. But, I had two different mechanics tell me that the ignition switch would be the last thing to go. I replaced it today and it seems to be working fine. Thanks for your help.
  • I am having trouble with my 97 GMC sonoma 4.3L V6. It is not getting any fire to the coil. I have replaced the coil, distributor, cap, button, pickup, plugs and wires, crank sensor, coolant temp sensor, and swapped out computer. Still no fire but it will turn over. Battery is good. Friend of mine hooked it up to a computer and its not reading any codes! What the heck can the problem be. I would really appreciate any advice because I am out of ideas! Oh and by the way when the truck broke down it backfired and blew out the top of a flowmaster!!!

    Thanks in advance for any advise!
  • gonogogonogo Posts: 879
    Thanks for the update.
  • I have encountered an issue with the tail lights on my 1999 S10 4.3L V6. Here are the symptoms:

    When ignition is off:
    - Brake lights on both sides work fine

    When ignition is on:
    - Left brake light is out, right brake light works fine
    - Left rear turn signal is out, right rear turn signal works fine

    Ocasionally, it decides to work correctly and there is no issue, but 99% of the time this is happenening. I have already replaced the left rear bulb, the flasher, the brake relay, and I have unplugged the cables near the back and checked for corrosion on the connectors for the tail light wires. None of these have helped. Can somebody give me an idea of what's going on?

  • So after changing all of the parts and nothing working I went to the GMC shop and talked to a friend of mine. Come to find out most sonomas have or will have this problem at some time or another. I thought I would pass on what he told me. There is a wire leading to ignition module that breaks. Its something easy to over look so if anyone else has any of the same problems that I had you may want to check it out. My truck is up and running like new! Cant believe I went threw all that trouble just for it to be a broke wire!
  • gonogogonogo Posts: 879
    Thanks for the heads up, throwing parts at it can cost.
  • 58flh58flh Posts: 1
    :sick: i am goen through the same sh....t help,,let me know what you found out....exhaust aint cheap hugh??? scooterroo
  • mikeysonmikeyson Posts: 4
    1999 s-10, 2.2 manual tranny.

    I am at a total loss on this problem, here's the issues:

    *When trying to start, it starts in a pattern every time:
    engine turns 3 or 4 times, pause (repeat 3 times), then engine turns until start.
    not working, doesn't matter if ignition is on or off. daytime running lights do not work either. Dash light for brights is always on, dimmer switch does nothing.
    parking lights come on
    headlight switch on or off brake lights are on
    headlight switch on -> side running lights come on
    press brake pedal while engine is running, engine dies
    remove brake light fuse, can press the brake pedal and engine does not die
    cab brake light functions normally
    *ac/heater fan
    switch on, engine dies
    the car will not start, (but engine turns), when switch is in any on position
    *hazard lights
    ignition on -> hazzard lights on solid
    ignition off -> hazzard lights function normally

    lots of odd issues eh? There are no engine error codes and everything else appears to function normally. Alternator was replaced, 6-8 months ago and start a month ago. Nothing recently aside from those. Any ideas before I start thowing money away at a shop??? Help!! :)
  • gonogogonogo Posts: 879
    Check all the grounds you can find, weird symptoms are usually grounds.
  • gcebulkagcebulka Posts: 1
    Hello All,
    I have a 2001 S10 FWD. I cannot get my high beams to stay on, nor will my fog lights work. If I pull and hold the the dimmer lever, the high beams will come on, but, once I release the lever, they go off. The fog lights will not come on at all, even after flicking the level a couple of times.
    Anyone out have an idea as to what the problem may be?
  • truc77truc77 Posts: 5
    I have a 98 S10 ,,,,,,I only have 5.1 volts at my fuel pump, when I hook 12 volts up to it pumps fine but the truck still wont start. If I pour gas directly into the throttlebody it will start and run til the gas is gone.. replaced relay, but still 5.1 volts any help would be greatly appreciated, Curt
  • gonogogonogo Posts: 879
    Check for 12 volts at fuse Cluster 11, if low volt replace ignition switch.
    The power feed to the pump also powers the injectors, hence no start.
  • truc77truc77 Posts: 5
    the ground checks out at 0 ohms to the connector at the rear. I have 12 volts entering and leaving the fuse cluster, something in between there has to turn it off when the pump make 55lbs, or does it shut off itself??
    If I pour gas into the throttlebody (or what ever it has) It starts, so I assume the injectors are good.
  • Sorry to jump in here late. Your fuel pump is only going to come on for about 2 seconds. Its called a 2 second prime by the PCM. Your tested fuel pressure at 55psi is with in specs. If the vehicle will start breifly by putting something flamible in the throttle body, verify injection pulse and power to the injectors. The pulse is controled by the PCM making use of a cam sensor signal, they are powered by the PCM. If you have power to the fuel injectors but no pulse while cranking the engine, most likely cause is a failure with the cam sensor. You can test for power at the injection plug with a test light, ignition key on run position. You can use a test light to check for the pulse also, but just buy a noid light and plug it in the injector plug and crank the engine. It will blink while cranking if the PCM is pulsing the injection system. Repost after those test.
  • gonogogonogo Posts: 879
    A bad cam sensor will not cause a no start, the PCM will just revert to the default
    setting and put the check engine light on.
  • gonogogonogo Posts: 879
    Lets start from the beginning, will the pump run 2 seconds with the key on run. Not jumped, but wired factory.
    When you put fuel in the intake you are not using the injectors, you by passed them.
  • mikeysonmikeyson Posts: 4
    All the grounds look good. Also tested the brake light switch and fan switch. The brake lights will go out if I remove the fuse, and I can hit the brake pedal okay at that point.

    Does the lighting link in through the computer? Not to focus so much on the lighting since turning the fan motor on also kills the engine. Does that link into the computer as well?
  • stumannstumann Posts: 7
    I've replace the starter twice on my 99 S-10 2.2 5-speed, 132,000 miles. This time I replaced the starter and flywheel. F'wheel had a broken tooth. It still acts strange. The engine tries to "kick back" when cranking. Reminds me of a wet distributor cap from years ago. I removed the ECM fuse and it cranks fine, so I'm pretty sure it's ignition related. Once it starts, it runs perfect, no check engine light, no codes. Someone suggested replacing the crank sensor and the cam sensor. I did, no change. I'm know I'm going to ruin another starter and flywheel if I don't solve the problem. Has anyone heard of this problem before? I do have new plugs and wires on it, but I've never replace any coils.
  • gonogogonogo Posts: 879
    I reread your first post, you have quite a mess there. Little history, did this just happen all of a sudden or was there work done or was it jumped.
    You say no head lights, I would start there first, with every thing off the head lights will come with the switch. Unplug one of the head lights, with switch on should be power there, I like to use a 12 volt test light in a situation like this.
  • stumannstumann Posts: 7
    Well, I took a chance a bought a couple of coil packs and installed them. That fixed the problem!! I hope this post may help someone in the future with the same troubles.
  • mikeysonmikeyson Posts: 4
    I will check the power to the headlights today. however I'm thinking there will be no power since the headlights do not come on (with the headlight switch on, the parking lights come on).

    So, here's what happened that day...I drove the car to work and everything was fine. I went back out after work and the car seemed to start normal, however I noticed the headlights were not on and the brights icon was on in the dash. I didn't really think anything of it until I hit the brakes and the engine died.

    The only work that has been done recently (aside from oil changes) is a starter replaced about a month ago and the alternator around 6 months ago. I did jump my sisters car a few weeks ago (not sure exact date).
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