I have a 97 gmc k1500 5.7 auto so I'm having trouble with voltage drop I will start it everything will be fine then I put the ac on or defrost it will drop voltage frome 14.5 to 12.2 when I turn it off it will go back up any help would be greatly appreciated
-
Welcome to The Truck Stop! We see you haven't REGISTERED yet.
Your truck knowledge is missing!
- Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
- We have tons of knowledge here for your diesel truck!
- Post your own topics and reply to existing threads to help others out!
- NO ADS! The site is fully functional and ad free!
Problems registering? Click here to contact us!
Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!
97 gmc k1500
- Thread starter BDJ1776
- Start date
-
- Tags
- voltage drop
Will L.
Well-Known Member
Defrost often engages the a/c as to dehumidify the cabin. You need to isolate if it is the a/c compressor circuit by unplugging the compressor and retest.
You have something shorting out or burning out from wear that is drawing too much power.
Or you could have bad ground causing it.
For the grounds, this is a GREAT thing to do to help everything work better anyways so start with it:
Remove battery negative cable from battery. Then, one at a time remove, clean, and reinstall every annoying ground wire on the engine and the couple body grounds under the hood. Then undo the positive battery cable. Clean and reinstall both battery cables.
If any of the rings are bad, replace them as you go.
I know this sounds stupidly annoying and like a catch all fix. But it is the best starting point always with any rig half this age or older. Then you know for the next decade (unless in the rust belt) the connections are ok. There is more to do, but start with easiest and most likely first imo.
You have something shorting out or burning out from wear that is drawing too much power.
Or you could have bad ground causing it.
For the grounds, this is a GREAT thing to do to help everything work better anyways so start with it:
Remove battery negative cable from battery. Then, one at a time remove, clean, and reinstall every annoying ground wire on the engine and the couple body grounds under the hood. Then undo the positive battery cable. Clean and reinstall both battery cables.
If any of the rings are bad, replace them as you go.
I know this sounds stupidly annoying and like a catch all fix. But it is the best starting point always with any rig half this age or older. Then you know for the next decade (unless in the rust belt) the connections are ok. There is more to do, but start with easiest and most likely first imo.