I have a 97 F150 and think I have a short. Lately I've noticed that my rpms will drop and the truck seems to want to die. I've also noticed that the batter, fuel, and oil pressure gauges are fluctuating and not working right. We attached a volt meter and to the battery and noticed that it fluctuates a little. The alternator has been tested and the batter has also been tested. Does anyone else have any other suggestions? Does the majority agree that it's a short? Any help would be appreciated...thanks!

 

Who tested the battery and alt.? Did they detect any fluctuation when they tested the alt.? Definitely shouldn't be a fluctuation, but I wouldn't necessarily say short. Make sure the connections are all good, as well as clean between the alt. and the battery. If those are good and the fluctuation is still there, I would still suspect the alt. in spite of the fact that they say it tests OK. Look for a ground problem, that is also a very real possibility.

 

Did you check that the battery and alternator ( including the alternator field ) wires are clean ?

If the field harness is having an issue, it can cause changing problems.

Here is a thread where jbrew has the info on the field harness

https://www.f150online.com/forums/el...nator-why.html

This would actually look more like an open vs a short.

 

Ok I have some what of the same issue, I have noticed that at night when only at braking to a stop my RPM's drop and my head lights will dim then RPM's come right back up and light get brighter, is this the same issue or no.

 

If it is a mechanical item causing the RPM drop ( which causes a low voltage condition ), take a look at the IAC ( Idle Air Controller ) on the back of the throttle body.

You will need to remove the plastic throttle body cover to get to it.