Hey y'all,
Got a 1999 Blazer 4x4 4dr LS, having major electrical issues, throwing 40 p codes. Any ideas?

 

Its difficult to help without knowing the codes and/or issues. More info please!

 

It went from running, no CEL, developed and intermittent grind, still no CEL, then this morning would'nt start. The codes are as follows, any help would be appreciated: images have codes in order. Thanks.

 

It seems your attachment didn't post. Try it once more.

 

Sorry about that, there ya go:

 

Could the intermittent grinding sound you heard have been an electrical short arcing? Are all the fuses good in both panels? The codes seem engine specific, I'm hoping we find something simple.

 

Agreed. That's a LOT of fault codes to pop up all at once...

 

That's a crazy amount of codes! Do they all come back after clearing them?

 

So, as best I can figure, all the involved codes come off of systems routed through the PCM, and the fuses and relays seem fine... I'm beginning to think that the PCM is toast. And yes the codes come back after being cleared.

 

I'm hoping the same. And to answer the first question, I'm not sure, but I don't think so. Pretty sure it was mechanical.