1998 F150 XLT with 130,000 miles on it.

Wife drove truck twice today--no problems. Third trip we go to the store. When we come out truck won't start. It turns over slowly for a second and then nothing. Lights on the trailer brake controller are going crazy while trying to start it.

Finally, a guy sees we are having problems and offers to give us a jump. It starts right away and we start to head home. I notice that the charging gauge on the dash shows nothing. Needle is at the bottom. The electrical system is acting weird. The radio turns on and off on it's own once. The power windows don't work. I notice that while signaling, the turn signal light on the dash doesn't light up but I can here it clicking. Lots of strange clicks coming from behind the dash.

Braking while going down a long hill on the way home ALL the gauges except the speedo quit working. All the needles (including the gas gauge) drop to the bottom and the gas light comes on. Then when I'm going back up the next hill, all the gauges start working again except the charge gauge.

Then for a few seconds, the battery charge gauge starts working before the needle again drops to the bottom. Truck drives fine all the way home--just electrical problems.

The battery is less than one year old--have had no prior symptoms.

Any ideas?

Thanks

 

Did you check the battery ?

Just because it is less than 12 months old, does not mean it is not the source of the problem.

 

Right, and I'd check the cable connections too - all of them, not just the ones at the battery. You have a truck that's old enough to have corroded/loose cable connections at the far ends, where the cables connect to components or to the engine/frame grounds.

- Jack

 

I checked the connections. They look okay. I cleaned the terminals and tried to restart. Battery was too low. I took the battery back to Walmart for testing. They recharged it and their machine said the battery was okay now. I put it back in the truck and now the truck starts. But I'll be watching that battery voltage meter. I suspect it will run until the battery loses charge again.

I was suspecting alternator here not battery.

I've had several dead batteries and several bad alternators in the past and every time I had the gauges or lights go screwy while going down the road after the car was jump started, it was the alternator not the battery. However, I've never had a problem with this particular vehicle before so now maybe it's different. I've just never had screwy gauges after jumping a dead battery before.

Any thoughts here?

 

Just for the info of others who might have a similar problem, it was the alternator that was bad.

We replaced the stock 90amp one with the optional 130amp unit so that it wouldn't have to work so hard running all my trailer lights and charging the trailer battery.

Maybe all the trailer towing I was doing contributed to the demise of my alternator.

 

I had the same problem on my 1998 F150 5.4 but i replaced the battery and alternator and it wont charge and i have checked the connections and cleaned them and they are all good and tight. I will charge the battery and cant even make it 10 miles before the efi runs the battery dead. Any ideas?

 

So it starts fine, as long as the battery is charged ?

Did you check the fuse for the rectifier field ?

The other problem could be the connector or wires for the rectifier field ( small connector on the alternator ).

Here is a thread on the topic of rectifier field check points

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