Battery voltage gauge reads only a quarter up, it used to be halfway?

Tiny
DOJUNIM
  • MEMBER
  • 1997 FORD RANGER
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
The truck runs for two days and the battery drains. Replaced alternator (3 times) replaced battery, replaced tensioner pulley and idler pulley as well as belt. Used electric meter on all alternator connections and all read as they should according to internet. Found one blown 15-amp fuse in PDI box and replaced, all fuses continuity checked okay. Cleaned battery connections and all ground wires as I found them. Ground from battery to body is good. The Gauge read fine for the first two days after the fuse replacement then quit but fuse is still good. Removed all extra personal added wires (Fog light and trailer harness). Can not find any fusible links.
Tuesday, September 5th, 2023 AT 12:26 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

There are two fusible links. However, normally when they fail, they don't start working again. Also, the fuse you replaced allowed it to work but the system failed again after a couple of days without blowing the fuse leads me to think it's a connection issue with that fuse. Let me know the fuse number if possible and confirm its location. Is it under the hood or the interior?

Also, when the alternator isn't charging, check the two red wires at the alternator for power. I attached the wiring schematic below, so you have a reference.

Let me know

Joe

See pic below.
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Tuesday, September 5th, 2023 AT 7:15 PM
Tiny
DOJUNIM
  • MEMBER
  • 4 POSTS
PCM fuse in the Power Distribution box under the hood. Sorry memory was 15 amp but actually 30. Both sides of fuse show continuity. The car was running with it blown. Where are the 2 fusible links? Are they a larger link or just a wire? Can they be accessed from the top of the engine?
Battery reads 12.2 volts sitting not running.
Battery reads 11.9 running.
Red wire from battery to Starter relay reads 12.2.
Red wire from battery to alternator reads 12.2.
Red wire s115 #3 from back of alternator harness to battery positive reads 12.2.
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Wednesday, September 6th, 2023 AT 5:57 AM
Tiny
DOJUNIM
  • MEMBER
  • 4 POSTS
When running voltage at battery reads 11.9 but starts dropping if load put on battery such as lights. Drops immediately to 11.6 and doesn't climb back up when lights turned off. All other fuses in PD box checked visually and by continuity across test points. All fuses in panel on left side of dash prove out good. Connection across starter relay large nuts shows good and 12.2 at each nut individually.
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Wednesday, September 6th, 2023 AT 10:54 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

It sounds like power is present where needed. You need to remove the alternator and have it bench-tested. I realize this isn't the original alternator, but it may simply be a faulty part. That is what it seems to be.

Let me know.

Joe
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Wednesday, September 6th, 2023 AT 5:27 PM
Tiny
DOJUNIM
  • MEMBER
  • 4 POSTS
The first alternator I replaced the old one with was one from another Ranger that I junked and the alternator was 1 year old. No difference. Replaced that one with one from AutoZone. No difference. I replaced that one week later under the warranty. No difference. 3 alternators and no difference.
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Thursday, September 7th, 2023 AT 9:51 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

Are you certain there is power at the alternator wires I mentioned above? If there is, start the engine so there is a load on the alt and see what the voltage is at the alternator, and compare it to the battery. We are missing something simple.

Let me know.

Joe
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Thursday, September 7th, 2023 AT 1:43 PM

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