Hello all

I am new to this forum stuff so please bear with me as I ask for help. I have a 2008 F150 that Im having a problem with. My volt/battery gauge has started acting a little crazy and going all the past high and almost back around to the low reading. I have had the alternator tested at a few different auto parts stores and the claim its ok, and the battery was giving a bad reading so I replaced it. The gauge will reset correctly when I unhoook the battery, and work correctly till I turn the truck off. After turning engine off and taking keys out the gauge never really settles all the way down/back to the left like it should. Then its like each time its started after that it continues to jump up on the gauges until it finally cant go any farther around. Has anyone ever had this problem? Is it possibly a dirty or loose connection somewhere?

Thanks in advance for any input
AJ

 

Two possibilities... 1. The voltage regulator in the alternator is going bad (very common problem with our year) and people testing it don’t test it correctly to find this.. 2. Which makes more sense from what you discribed is a short in the gauge in the cluster.. bad clusters are another common problem with our year. If you have a multimeter you can read the alternator power while running to see if it’s jumping around.. it should read 14+ VDC if it’s working correctly. Are there any other weird things going on with power.. like flickering lights or batt light coming on ? BTW welcome to the Forum.

 

Nope, thats the only thing that seems to be off. Both autoparts I went to where showing it to be holding a current right at 14 as you stated, and this has been going on for about a month now so I would like to think if it was the alternator going out it would have went by now and left me stranded...but im no mechanic. Is there a more specific way to check the regulator thing you mentioned before I go buying an entire new instrument cluster?

 

Test it under a load... something drawing some voltage from it. Turin on headlights and fan motor.. radio..

 

 

Fyi any computer controlled relay (12v pin on 7way). Pull the relay out of fuse box and put a jumper in. This will give you 12v all the time, just be mindful and don't kill your battery.