Dealership can't fix or find on going electrical issues

pagrunt · September 13, 2014

Got an issue with my '08 Silverado lights flickering & radio popping when the brake lights or 4 ways come on then progresses into the dash going nuts. They replaced the under hood fuse box in April & the ECU this past week. All of this has been on & off since February with a short break in June & July. The service manager & the tech working on it are lost, admitting they have no clue to fix it. The Alternator was replaced in January '13 with similar issues. Anyone dealt with this & have an answer?

02suburbanZ71 · September 13, 2014

Check the grounds maybe bcu

JMG_TX · September 13, 2014

My 08 was doing strange things like yours. Gauges dropping out,Turn on the blinker radio turns on and off etc. Low voltage during heavy loads. Here is what I did to cure my problem for the last 30k miles no issues.

1. Inspected my Maxi fuse and it had discoloration. Cleaned and sanded the studs that hold the fuse and installed a new Maxi fuse.

2. Checked the connections on my battery and they came back with a high resistance. So I cut off the factory connections and installed new positive and negative terminals.

3. Cleaned my grounds under my hood by the brake booster

4. Cleaned and sanded all my hot leads to my fuse block and alternator

5. Put in a New Optima Battery (Yellow top) My OEM battery was already on the edge so I replaced it.

6. I cleaned every chassis ground. I found the one under my core support to not have very good contact at all. The one on the frame on the drivers side was not loooking to good also but not as bad as the front on the core support.

Once I was done with all of that and I started the truck I measured my output voltage and I was at 14.1 VDC. I started off with a reading around 12.8 (cold). Your BCM is doing alot of voltage control but bad connections to all the sub systems will cause the issues you are having. Hope that helps.

Video of what it was doing. This is just the radio. But it would shutdown everything at times of high loads.

pagrunt · September 16, 2014

Replaced the 175 amp fuse, cleaned all the cable ends & the nuts. Put dielectric grease on all contact points. So far, so good on the 1st drive. Going to put it on the highway tomorrow for a extended run to see what happens. Regardless, will be checking all grounds make sure everything is good.

Stex · November 7, 2014

My 08 was doing strange things like yours. Gauges dropping out,Turn on the blinker radio turns on and off etc. Low voltage during heavy loads. Here is what I did to cure my problem for the last 30k miles no issues.

1. Inspected my Maxi fuse and it had discoloration. Cleaned and sanded the studs that hold the fuse and installed a new Maxi fuse.

2. Checked the connections on my battery and they came back with a high resistance. So I cut off the factory connections and installed new positive and negative terminals.

3. Cleaned my grounds under my hood by the brake booster

4. Cleaned and sanded all my hot leads to my fuse block and alternator

5. Put in a New Optima Battery (Yellow top) My OEM battery was already on the edge so I replaced it.

6. I cleaned every chassis ground. I found the one under my core support to not have very good contact at all. The one on the frame on the drivers side was not loooking to good also but not as bad as the front on the core support.

Once I was done with all of that and I started the truck I measured my output voltage and I was at 14.1 VDC. I started off with a reading around 12.8 (cold). Your BCM is doing alot of voltage control but bad connections to all the sub systems will cause the issues you are having. Hope that helps.

Video of what it was doing. This is just the radio. But it would shutdown everything at times of high loads.

Good info Thanks. Excuse my ignorance but the location of the Maxi fuse is ???

Also a little off topic but put in a fresh Delco Monday (truck oem died in the pasture, thank the Lord for jump box always carried) but had to drive 40 miles on alternator to the parts house.

Now My alternator is now always charging full. 14.9-15. Battery in AM is 12.84. Will not come off full charge now for over 175 miles. All checked good at my local shop with their handheld? Worried about the always full charge. Almost to the point of removing alternator for a test at a professional shop.? BCM?

pagrunt · November 8, 2014

Well, after 2 months, the issue is back & filed a claim with GM to get this resolved. This is a WTF thing now, wondering why the never did a recall on an issue like this. My co-worker who followed me to the dealer said the brake lights didn't work. Damn truck cost me more to sit than drive. Since February, the ECM, air bag module, mega fuse, main fuse box, & battery have been replaced, the grounds have been checked & greased. There is enough dieletric grease on it to lube the entire porn industry. Maybe the BCM is bad, the battery cables might be bad, maybe there is too much electronic B.S. on the truck than it needs. Anyone have the GN p/n for the large bolder to crush my truck?

02suburbanZ71 · November 8, 2014

Well, after 2 months, the issue is back & filed a claim with GM to get this resolved. This is a WTF thing now, wondering why the never did a recall on an issue like this. My co-worker who followed me to the dealer said the brake lights didn't work. Damn truck cost me more to sit than drive. Since February, the ECM, air bag module, mega fuse, main fuse box, & battery have been replaced, the grounds have been checked & greased. There is enough dieletric grease on it to lube the entire porn industry. Maybe the BCM is bad, the battery cables might be bad, maybe there is too much electronic B.S. on the truck than it needs. Anyone have the GN p/n for the large bolder to crush my truck?

If the dealer cant fix it like you said- call gm and take to another dealership. Maybe another member who had this same issue can post some hints on a fix

gmtech4 · November 8, 2014

Well, after 2 months, the issue is back & filed a claim with GM to get this resolved. This is a WTF thing now, wondering why the never did a recall on an issue like this. My co-worker who followed me to the dealer said the brake lights didn't work. Damn truck cost me more to sit than drive. Since February, the ECM, air bag module, mega fuse, main fuse box, & battery have been replaced, the grounds have been checked & greased. There is enough dieletric grease on it to lube the entire porn industry. Maybe the BCM is bad, the battery cables might be bad, maybe there is too much electronic B.S. on the truck than it needs. Anyone have the GN p/n for the large bolder to crush my truck?

has anyone actually hooked up a tech2 to this truck ?????