LMM: Has anyone seen this before

[dmax lb7]

I have a 2008 3500 in right now that came in with all sorts of problems. After replacing the ECM it is running again. The problem is about every 10 seconds or so there is an arc from the balancer to the front cover or bottom of the water pump. Almost like a spark plug, lots of voltage. It doesn't do it all the time, but most of the time it does, only with the engine running. No codes and it runs good. Any ideas?

 

[catman3126]

Post a video of that? I remember reading about someone seeing this quite awhile back once.

 

[c20elephant]

Replace the serpentine belt and see if it goes away.

 

[dmax lb7]

Thanks for the replies. In trying to make it do it I found it only happens with the a/c on. Thinking bad pulley and coil assembly.

 

[TheBac]

Check the balancer. The rubber between the inner hub and outer ring may have pushed out the back and is causing the issue. Weird, but possible,

 

[NC-smokinlmm]

I'd look at the solenoid for the ac clutch assembly first.

 

[Chevy1925]

Bad ground somewhere. Make sure all known grounds are good

 

[TBone]

There is a GM service bulletin that basically says to check if owner has replaced the serpentine belt with an aftermarket, Some aftermarket belts have a compound in them that makes them prone to slippage thus generating static electricity. According to the bulletin it usually causes problems with the TCM.