1997 Ford F-150 Charging system

Tiny
JBNY
  • MEMBER
  • 1997 FORD F-150
  • 6 CYL
  • 2WD
  • MANUAL
  • 137,000 MILES
New battery will not charge. New alt/reg did not solve problem. During testing, grounding the regulator proved 18 volts from alternator. New regulator and known good regulator all act the same.
At one point, grounding the regulator would make the system work properly until engine was shut down. This no longer happens.
Followed testing procedures laid out in Haynes manual and everything says replace regulator. Does not fix problem
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Friday, September 17th, 2010 AT 12:23 PM

12 Replies

Tiny
WRENCHTECH
  • EXPERT
Follow the orange with lt. Blue wire from the alternator and look for a 20amp inline fuse and check that.
Also check all the fuses in the under dash fuse box. There is a 10amp fuse there associated with the alternator but I don't know what it's labeled. Use a test light to check them all for power at both ends with the key on.
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Friday, September 17th, 2010 AT 12:41 PM
Tiny
JBNY
  • MEMBER
The mini fuse is intact as well as all the fuses in the circuit. Power is where it's supposed to be and grounds are intact. The alternator puts out 18 volts when the IAR is grounded at the test point.

Wiggle tests showed no irregularities and I'd rather not be opening the harness unless I have to. The circuit is fairly simple with only a clutch interrupt switch and ignition switch involved. I get the feeling this is a unique problem and am totally stumped as to how to proceed.

Being able to ground the IAR and have the system work properly is really throwing me, especially since now it no longer does that. This is making absolutely no sense.

BTW-thanks for responding. I was an ASE certified Ford wrench for ten years specializing in EECIV systems and driveability. I've never run across this.
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Friday, September 17th, 2010 AT 1:43 PM
Tiny
WRENCHTECH
  • EXPERT
If you don't want to listen I'll just go help someone else. Good luck.
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Friday, September 17th, 2010 AT 1:45 PM
Tiny
JBNY
  • MEMBER
Did I miss something about what you said? The org/lt blue wire runs to the fuse you mentioned and turns into a yel/wht wire. Continuity checks and voltage drop checks all show normal. All fuses were checked after your advice with no irregularities, including those in the power distribution box.
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Friday, September 17th, 2010 AT 1:55 PM
Tiny
WRENCHTECH
  • EXPERT
I'm sorry. I got the impression you disagreed and blew off the checks.

The alternator is a self contained unit so if all the inputs and outputs are correct, then it has to charge, assuming the alternator is good.

Verify power coming in on the orange/lt blue and the lg/red with the key one. Verify there power at the main terminal with the key off and that the alternator is grounded.
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Friday, September 17th, 2010 AT 2:02 PM
Tiny
JBNY
  • MEMBER
No it's my turn to apologize for the negative feedback I gave after your snarky response.

There is no power on the lt grn/red wire with KOEO. A test vehicle right beside this one confirms there should be. This line comes from the instrument panel charge indicator so I believe you've given me a direction to go in. I will be back after I trace the wire backwards from the alternator.

What is your experience with where I might find the problem in the circuit?

TY again.
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Friday, September 17th, 2010 AT 2:25 PM
Tiny
WRENCHTECH
  • EXPERT
Green red comes from the fuse in the dash box through the charge light in the dash so it could be interrupted at the back of the cluster. It's white/yellow from the fuse to the light.
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Friday, September 17th, 2010 AT 2:43 PM
Tiny
JBNY
  • MEMBER
It's even simpler than that. You'll get a kick out of this. When I checked the fuses in the fuse box earlier today I physically took each one out and looked at it. Then your advice got me back there checking again with the same results-everything's OK.

Rather than yank the cluster out I went to the fuse box again and was going to work up from there. Well, the 5 amp mini fuse in the circuit (#19)was still OK BUT when I put it back earlier I put it in the slot above where it was supposed to go. DOH!-I boned myself. Your check at the IAR connector is what got me there and I can't thank you enough.

How do I get you $ for this-you certainly earned it?
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Friday, September 17th, 2010 AT 3:19 PM
Tiny
WRENCHTECH
  • EXPERT
Glad you found it.

I don't need money but if you can leave another positive or fix the feedback it would be nice. I don't even know if that is possible.
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Friday, September 17th, 2010 AT 3:24 PM
Tiny
JBNY
  • MEMBER
Unfortunately I get a message about "spreading it around" when I try to give you points and I don't see a way to retract it. I will try tomorrow (maybe it resets the points thing.)

Thank you again.
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Friday, September 17th, 2010 AT 3:40 PM
Tiny
TBRWOLF
  • MEMBER
Question have done all the things you have listed no charge?
I can hook up to other vehicle with jumpers and shows charge? Where should I look oh by the way new alt and bat
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Tuesday, May 1st, 2012 AT 12:24 AM
Tiny
TBRWOLF
  • MEMBER
Sorry ment this for Wrenchtech
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Tuesday, May 1st, 2012 AT 12:26 AM

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