Electrical gremlin in my 2007 GMT900

[RedHeartbeat]

Well, this has been going on since day 1 when I bought this truck new and it's getting aggrevating. My truck has this gremlin in it that kills the power to the lights and other items when I come to a stop. I'm sure it's going on all the time but it's most noticable during braking. My headlight flash like they were turned off and then on. The engine stalls and then refires. When logging with HPTuners the timing will drop to almost nothing and then back up to normal. While driving the timing will do the drop and recover, too.

Any ideas? I've checked and tightened all grounds and power wires.

[pl4yboy]

Alternator?

[T-Stark]

both of my buddies that have owned 07+ gms have had the same problem, they took them into chevy and said there was a short in the harness.. they they put a new harness in under warranty, 2 days later same problem truck died in the middle of the intersection and had to clear the computer to start it...

sorry im not much help good luck with it tho!

[ecld_07]

Mines done that a bunch. I found the battery connector terminals didn't fit properly. Even when I tightened em it didn't fix it. Put new connectors on and havnt had an issue in a few months

[Botlfed]

Take it in for warranty greg, think its voided had a similar problem with mine, like shawns the terminals were wore out.

[GasGuzzler]

Answered via text Saturday. I'd prove it to you Greg but you need my Fluke and I don't loan it.

[RedHeartbeat]

Seriously? I didn't get the text for some reason.

[GasGuzzler]

Explained via text today.

For those with this type issue on an '07 or '08 GMT900 do this.

Disable fuel injectors
Attach one Fluke lead to the negative battery cable at the battery and one to the negative battery cable at the RH head.
Set the Fluke for DC voltage and use the min/max (record) function.
Crank the engine for about 10 seconds.
Review the MAX reading on the Fluke.

If it's more than 200 mV, replace the cable. New (good) cables test about 100-120 mV.

It's not common and there is no recall. I have fixed four or five trucks with off the wall electrical issues with this test. There is a bulletin. It might apply to 2009+ but I have only seen earlier builds of the GMT900 with the issue.

HTH all

[RedHeartbeat]

Had Nathan check the battery cables today and both had issues. At least other power leads were okay, just the main battery cables. I guess I'll throw more money at it.

[GasGuzzler]

Way worse than any I have tested before. Not saying all issues will be gone but....can't hurt to get these fixed.