Hello All,

Having an issue on my 97 f150 where the battery light is on constantly. The light has been on for a few days and the battery died on me this morning after running it only for about 10 minutes. Took the battery over to sears to have it checked and they said it charged and tested fine. Put the battery back in and, sure enough, the battery light stayed on. Am i looking at an alternator issue here? It seems to me like the truck is just running off the battery and after a few days, runs out of juice. I think it is the original alternator. I have had the truck since June of 2000 and i have never replaced it. Any thoughts?

Thanks in advance!

 

start the truck and take a voltage reading at the battery posts, see what it is... than go to your firewall, where you MAIN fuse breakers are and test the output at the cable that leads to the alternator....

First ofcourse, check the fuses for your alternator.

Earlier this year my stock(1998 184,000 mile) alternator went out... I had warnings for months, such as battery light flashing, but ignored it... it than bite me in the *** in the middle of PA when my truck died..

 

Not sure, but I thought the 97/98 MY trucks have an alternator field fuse that was not in the engine compartment fuse panel.

If this is out, the truck would not charge.

This is a 20A inline fuse between the 175 A mega fuse for the generator ( the Black w/ Orange stripe cable ) which breaks into 2 leads to the Alternator. The inline fuse is on the Yellow w/ white stripe, which then changes to Orange w/ Light Blue stripe wire after the fuse.

Worth a check at this point. Also check the connector for this on the alternator, to make sure the connector did not get damaged in the swap.
jbew has this happen once to him, and he had to rebuild the harness.

The power should be at the Orange w/ Light Blue stripe wire all the time.

 

yea, the field fuse is out connected to the 175 breaker, but there is also a 10 amp in the passenger kick panel that if its blown it will not charge

 

1997 MY does not have a fuse panel in the passenger side kick panel.

 

sorry, little mixed up. meant passenger conpartment... but I mean by the drivers leg... that fuse panel. sorry

 

Not showing in the EVTM that I can find.

Only 10A Fuses in the CJB are :
19 : Instrument Cluster, Air Bag Diagnostic Monitor
22 : Air Bag Diagnostic Monitor, Passive De-Activation (PAD) Module
23 : Trailer tow Battery Charge Relay, 4X4 Hub Solenoid, 4X2 Hub Solenoid, Flasher Relay, Shift on the Fly Relay
24: Blower Relay
26 : Daytime Running Lamps (DRL) Module, Right Headlamp
28 : Left Headlamp

The only other 10A fuse in the BJB is Fuse #2, Air Bag Diagnostic Monitor

Nothing about charging for the truck's system ( only trailer battery via the 7 pin trailer tow adapter ).

 

I know, I was checking for fuses for charging last time I thought my alternator was dead... I wasnt charging adnd was running off of the battery. I remember I had took out my power wire fo rmy gauges the night before. I slid it behind a 10 amp fuse in the block. I checked the block, sure enough that fuse was partially sticking out. I pushe di tback in and my gauge jumped up and I was now charging at over 14 volts instead of running at 11.9

 

If you mashed a wire behind CJB Fuse #19, this would have an impact on the charge gauge on the dash, but not the actual charging of the truck.

 

Camaro, where is this 10 amp fuse that was sticking out? I am planning on checking the fuses in the morning. Just want to make sure I check the right ones. Thanks.

 

the 10 amp is indeed number 19.... It is indeed responsible for the charging system. I found out it the same as the Super Duties. Remember how they have that issue where the OD button rubs on the steering column, it wear through to bare wire, shorts, than blows the fuse responsible for the DASH lights and CHARGING system! Yes it does.

Let me reiterate my story...

I had removed my aftermarket gauges, in which one of my gauges was powered through the #19 10 amp, well when I pull the wire from the back of that fuse, the fuse got ****ed and wasnt completely in.... Next day I went to work, noticed everytime I moved my setting on my heater controls, the voltage would drop. Even when I turned my marker lights on and off, the needle would move, odd.

I brought the truck in the shop, noticed while running the voltage through my system was 11.9. I took a reading off of the alternator directly, same thing... I checked my fuse panel for a charging fuse, didnt find one. Check the one on the 175 amp, it was fine. I pulled the cover off the CJB and saw that one 10 amp was ****ed... I pushed it in, my volts went right up and my system was now charging at 14.3 volts....

Pull that fuse and see what your charging system does, no?

 

Sure this time?
In OCT-09 a problem with fuse #18, your posted cause was the OD wires rubbing, and no mention of the charging system ( at least with this MY the F-150 and the F-250 are the same electrically ) .

 

yea I did not mention the charging system in that thread, it didnt have much to do with it...

The Super Duty I worked on, when the harness would rub, and blow the fuse, the truck would only run for a short distance than die... The guys were pullin hay with it so they didnt need the cluster, but when they ran it for long enough time, the truck wouldnt run anymore, and it needed a jump, even then it would only make it so far... They went through like 10 fuses before I got there to fix the issue

 

Checked all fuses and they tested ok. Battery light remains solid and constant. Alternator replacement next?

 

did you check the field fuse, and the harness for this ( including the connector ) ?