View Full Version : 03 GM 6.0L problems, AGAIN!!

11-03-2009, 09:29 PM
I'm loading some parts into the back of my idleing truck tonight when it starts to stutter and run rough, after about a minute it died. Now it wont even crank over. 13v on the guage, lights come on in the key on position but you dont here the fuel pump, or starter sol. If you twist the key to the start position the lights go out completely and nothing happens, no crank, no sound at all..nothing.

Any thoughts...

11-04-2009, 10:05 AM
I would suspect a failed ignition switch. They have been problematic. But first I would check the battery under load it could be something as simple as a bad cell. Maybe throw a jump on it just to check before humping the battery to a shop.

11-04-2009, 07:10 PM
I threw jumper cables on it tonight to eliminate the possibility of a bad battery or ground. With the cables grounded to the truck frame I had 14V on the truck guage. Every electronic thing works but when I turn the key to crank the headlights quit and as soon as I let off the crank position back to "key on" all the guages momentarily zero and settle back to where they were.

11-04-2009, 09:35 PM
If you have a shorted cell in the batrtery, they can act like that. You can get volts but no amps.

The shorted plate will suck up what the alternator puts out, preventing it from running.

11-04-2009, 09:46 PM
I work at a GM dealer. Check the battery terminals very well. The Delco batteries have a habit of braking off the lug that the battery cable screw to.Jeff Wurl

11-04-2009, 10:10 PM
I second the bad connection somewhere. A primary lead. Positive or ground. Check both ends of both cables. It will carry the voltage until you put a load on it. A bad connection makes heat and will do what you described.

11-04-2009, 10:45 PM
I had an issue a couple years ago where the hole drilled into the side of the battery for the cable connection wasn't quite deep enough. It would tighten, but the bolt would bottom. It was just enough to cause some intermittent fits. I stuck a 3/8" lock washer under the bolt and the problem went away.

Forgot about that one.

11-05-2009, 01:30 PM
I pulled the batterey out and it load tested fine. Is it possible to test OK and still have a shorted cell?

11-05-2009, 01:38 PM
No. Load tests are definitive.

It took me a long time to figure out the battery bolt bottoming thing.

Take a look at grounds as well as the + side connections. I had one GM pickup that had some work done at the shop. Had an intermittent electrical problem. Finally discovered a junction block connection on the firewall- the tech had pulled the big red wire off to do the work and on reassembly, put the nut on finger tight but never put a wrench to it. Took hours to find it, seconds to fix it.

11-09-2009, 03:28 PM
Be weary of side post batteries that GM loves to use. The side posts will pull out, particularly when hot causing battery failures.

11-09-2009, 04:18 PM
get a known good battery, clamp neg to the block, positive to the starter input and see if it turns or looks like the 4th of july.. if the starter is doing a dead short that would wipe everything momentarily when you turn the key

11-09-2009, 06:28 PM
Tony, except fot the "stalled and now fails to crank" part, what you are describing is normal operation. Crank position removes power from the accessory relay meaning all the lights, guages etc go dead while in crank position. That saves cranking power for the starter.

At this point, you need to verify the ign switch and crank relay.

Check the 10 amp IGN E fuse in the under hood box first.
Check the 40amp IGN A fuse same box
Check 10 amp CRANK fuse same box.

At the switch, you need to have battery power on the red / white wire and power out on the white and pink in crank and run position and power on the brown in run.

The actual crank wire is the yellow and should be battery power in "crank" only.

Beyond that, you can check at the crank relay in the under hood box. Two showing power in crank, one true ground from the PCM and the forth is the crank output wire to the starter solenoid.

Failing that, get a hold of me tomorrow before I leave for KW and I'll try to help you out.

11-11-2009, 03:41 AM
I work at a GM dealer. Check the battery terminals very well. The Delco batteries have a habit of braking off the lug that the battery cable screw to.Jeff Wurl

Mine did that on my 2001. I have dual batteries and the secondary battery actually went completely dry. I checked the other one and the entire post came out of the side of the battery.

11-14-2009, 09:30 AM
If the posts aren't pulling out of the battery, I second the ignition switch. Sometimes they will even check good with a test light, but not with a load.

11-14-2009, 12:58 PM
The crank fuse was blown, and the fuel pump shot. I have the new fuel pump now the problem is the harness plug is different and the wire colors on the new pigtail for the new pump arent the same colors as the existing harness.

It will be a cold day in hell before I buy another Chevy truck.


11-14-2009, 01:25 PM
Tony, have you talked to Fundy about this?? You may want to shot him a pm...

11-14-2009, 10:28 PM
The pump has a wiring diagram in the directions to show you how to do the plug.

11-16-2009, 06:30 PM
The directions that came with mine did not include a wire diagram, it just said "match wires accordingly". I was actually suprised that the the folks at AC Delco took the time to fax me the diagram.

For future reference, if anyone else has this prolem. The smaller of the two black wires on the truck end goes to the orange w/black tracer. wire on the new pigtail end.