All,

I am new here and I just wanted to thank the community for always being helpful in the past. I have relied on multiple posts to rectify issues I've had with my Silverado but the issues I am currently having, have me stumped, and are costing me an arm and a leg.

My Truck - 2007 Chevy Silverado 1500 (NBS) LTZ 5.3 - Bone Stock - No LED's anywhere or after market radio

What is currently happening:

• Whenever I am in cruise control and use my turn signal, it sometimes cancels my cruise and I can see the dash light flicker.
• Even the use of turn signals make the dash light flicker (This is observed when voltage is at 14 or below)
• The dash light also flickers sometimes when I press the brakes. Occasionally I will also hear the radio pop
• When I turn the truck off the radio sometimes makes a pop noise like killing the motor is surging or shorting something (The radio should remain on via Retained Accessory Power) and the dash light flickers as well

What I have tried

• Cleaned both battery terminals and cable ends
• Cleaned A frame ground to bare metal
• Cleaned all ground ends coming off of the negative battery cable
• Ran an additional ground from firewall to below alternator framing for a ground point (Saw this via a YouTube video)
• Confirmed firewall to engine cylinder head ground is still strong and not corroded
• Took it into a GM dealership and had them look over everything and update all computer modules (only update that was performed was a radio update)
• Battery was swapped in November of 2022
• Alternator was tested
• Confirmed fuse box under hood was free of corrosion and has good contact

I am at a complete and total loss. Please help.

Thank you all!

 

I should mention that two weeks ago I had a flashing airbag light on my dash, my mirror compass and thermostat display was freaking out and my radio was cutting in and out. Not sure if this helps any. That only happened once though.

Please help.

 

If you’re still needing an answer…

The common tie to all of these components/issues is the BCM. It’s directly responsible for controlling the lights/turn signals and has connections to the radio via the illumination circuit.

The BCM’s on these trucks are known for being problematic. As they age they become more susceptible to moisture contamination from humid air. If the problems seem to be more prevalent when it’s raining, that’s a good indicator the BCM is to blame.

A couple of things to try:

1) Perform a battery cable reset. Disconnect both cables from the battery and connect them to each other with vise grips or a jumper wire for at least an hour. This discharges the backup power for the BCM (and all modules) and resets them to their original settings from the factory (won’t undo any updates).

2) Remove the BCM from the truck and put it in an air conditioned space for a couple of days. If the issues seem to be resolved, it’s likely the BCM is due for replacement.

 

@Gumby22 Thank you for the advice. I thought my issues were limited to when it rained but that was disproven not long ago when the weather was nice and dry and the issues presented themselves.

 

Let me ask this. Under the hood you can see where the ac drip hose is. As I wait for my positive battery cable to arrive I noticed that the one end of the positive cable going to the starter is having that AC hose water drip on it and I swear I can hear that water sizzle when it lands on the positive battery cable. Should that cable be so warm that it results in that water sizzling?

 

If the cable is getting that hot just from operating the starter, no. In that case, one of the cables is bad or the starter is drawing far too much current.

If that’s happening after the engine has been running for some time, the vicinity to the exhaust could be causing the cable to heat up enough to cause it, but within a couple minutes of shut down, it shouldn’t be that hot. Even then, it depends on how well insulated it is.

 

Interesting to note. I only noticed this today after a 20 minute drive and I parked it. I was running the ac and I wanted to open the hood to check everything over again. Thats when I noticed the water droplets coming down and dripping on the positive battery cable end that goes to the starter. It looked incredibly well insulated and wrapped in a silver colored tape along with the black cable shielding still in place but that cable felt warm. As that water dripped I heard the sizzle. I wish this site allowed me to upload pics.

 

I’m not sure of the guidelines, so a forum moderator would need to confirm this, but you may be prevented from uploading pics because you’re a new member.

However you should be able to post a link to pics on another site.

If it’s the silver insulation that the water is dripping on, I’m not surprised it’s sizzling - that means the insulation is doing its job.

 

Yessir, that's where its sizzling. Once its hitting that silver insulating tape.
However, the cable should not be getting that warm, right?

 

Under normal operating conditions (no faults with starter system, battery, alternator, etc), no; nor should it be getting that hot from the exhaust.

But that’s the actual copper cable - the sheathing and insulation can withstand higher temperatures and that’s why the silver wrapping causes the sizzling.