1998 Ford Ranger 1998 Ranger, new alternator, battery light

Tiny
WAB
  • MEMBER
  • 1998 FORD RANGER
Electrical problem
1998 Ford Ranger 4 cyl Two Wheel Drive Manual 78k miles

Just installed a new (rebuilt) alternator, the in dash battery guage looks fine, right where it always has been since new. But the battery 'light' stays on all the time now.

I get 12.5v on my (new) battery, and 14.5v with my handheld volt meter after I start the truck. So everything looks good, except for that dash 'light'!

Even when my old alternator (regulator) was going bad, the battery 'light' would only flicker and sometimes stay on dimly. Now it's on BRIGHT all the time. What could be wrong?
Do you
have the same problem?
Yes
No
Monday, December 15th, 2008 AT 5:48 PM

5 Replies

Tiny
DAVE H
  • EXPERT
Alternator Light Stays On With Engine Running
Loose or worn alternator drive belt. Check alternator drive tension and condition, See Belt Adjustment in TUNE-UP article in the TUNE-UP section
Loose alternator wiring connections. Check all charging system connections
Short in alternator light wiring. See Indicator Warning Lights in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Defective alternator stator or diodes. See Bench Tests in ALTERNATOR article
Defective regulatorSee Regulator Check in ALTERNATOR article
CHARGE INDICATOR ALWAYS/NEVER ON
Turn ignition off. Check for continuity across fuse No. 15. If fuse No. 15 has continuity, go to next step. If fuse No. 15 does not have continuity, repair short to ground in fuse feed circuit and replace fuse. See WIRING DIAGRAMS.
Disconnect generator 3-pin connector. Turn ignition on. Connect jumper wire between generator 3-pin connector Light Green/Red wire and ground. If charge indicator illuminates, see appropriate GENERATOR article in the ELECTRICAL section. If charge indicator does not illuminate, go to next step.
Turn ignition off. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Disconnect instrument cluster connector C216. Measure voltage between ground and instrument cluster connector C216 terminal No. 2 (Yellow wire). See Fig. 4. If voltage is more than 10 volts, go to next step. If voltage I s less than 10 volts, repair open in Yellow wire.
Turn ignition off. Measure resistance of Light Green/Red wire between instrument cluster connector C216 terminal No. 3 and generator 3-pin connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Light Green/Red wire.
Check for continuity between charge indicator bulb terminals of printed circuit. See PRINTED CIRCUIT under REMOVAL & INSTALLATION. If continuity exists, replace printed circuit. If continuity does not exist, replace bulb.
Was this
answer
helpful?
Yes
No
Monday, December 15th, 2008 AT 6:00 PM
Tiny
WAB
  • MEMBER
Great explanation Dave, but it's going to be pouring rain here for days (then freezing cold), so I won't be able to check as I would like right now.

A couple questions though -
Are new alternators known for blowing that fuse #15 (7.5amp) when they first start up (amp surge)?

Can the entire charging system work fine (as mine seems to) with the 'I' circuit open (blown #15 fuse, or open LG/R wire or bad 'I' in the regulator)?

That fuse is also shared w/ the air bag circuit. So my air bag doesn't work either? I can't find a air bag schematic. No big deal.

Right now my truck seems to run GREAT. It's just that idiot light?
Was this
answer
helpful?
Yes
No
+1
Monday, December 15th, 2008 AT 11:35 PM
Tiny
WAB
  • MEMBER
Well I re-read my Haynes manual, and in a 'bubble' on the charging system schematic it basically states that - the entire S & I circuit is dedicated to turning that idiot battery light out!

It ended up being that single S wire connector at the diode pack of the alternator.I put a small finish nail in the connector (to make a good connection) and the battery light went out!

I also use small finish nails in the fan connector under the hood to get all speeds of the fan to work. Great quick fix for these connectors.
Was this
answer
helpful?
Yes
No
Tuesday, December 16th, 2008 AT 1:23 PM
Tiny
DAVE H
  • EXPERT
Well done . Happy xmas and new year.

Happy motoring

Dave H
Was this
answer
helpful?
Yes
No
Tuesday, December 16th, 2008 AT 3:00 PM
Tiny
WAB
  • MEMBER
And a merry x-mas & new year to you too!

Bill
Was this
answer
helpful?
Yes
No
-1
Tuesday, December 16th, 2008 AT 3:08 PM

Please login or register to post a reply.

Recommended Guides