volt meter and battery light

82,995

Asked by Mar 05, 2013 at 10:27 PM about the 1996 Isuzu Trooper 4 Dr Limited 4WD SUV

Question type: Maintenance & Repair

Volt meter reads normal, about 14 volts at idle and battery light is off, if you accelerate like climbing a slight hill or passing on the freeway the voltmeter drops to just under 12 volts and the battery light comes on, if driving at night you notice the lights also dim, back off the gas and everything goes back to normal. I was told it was the alternator so I replaced it and all of the belts, same problem, took out the new alternator and had it tested, and it checks out very good, the guy told me that this is a ECM controlled alternator and that might be the problem.  I put the alternator back in and checked wiring up the side and to the main plug in the engine bay, didn't find any problem there.  Anybody got any ideas?

9 Answers

the voltage regulator is part of the alternator...maybe you got a dud. It's not unheard of.

18,955

I think the troopers had a blue relay or something tied to the air cond. relay and one is for charge , look at relay box

1 out of 1 people think this is helpful.

..wow kinda guru-ey, just like the genie...

85

Your ignition modules(units the plug wire come from) could be failing and forcing the battery to supply the missing voltage during acceleration, or under load.

92,015

First thing that came to my mind is a broken wire or bad electrical connection. When the engine is under load, it moves in the mounts, pulling on a wire and the circuit opens. - Give the wiring a close look before throwing more alternators and ECU's at it.

2 out of 2 people think this is helpful.
Best Answer
70

I had a similar sounding problem once. What I found was the engine ground strap was broken and as the driving torque of the engine increased like climbing a hill or accelerating, the engine would lift just enough to loose the ground. This sounds impossible but ground the engine to the frame & engine to the battery and see what happens.

2 out of 2 people think this is helpful.
82,995

Thanks for everyone that responded to my problem. The problem was the ECM, for some unknown reason it would put the alternator into economy mode during acceleration. ECM replaced problem is gone. Happy Trails

5 out of 5 people think this is helpful.

please click 'mark helpful' for those of us who you thought were helpful. I gave you ten points....just 'cause I can~

1 out of 1 people think this is helpful.
20

Since the alternator is control by the ECM find out which wire from the alternator go to the ECM. Cut that wire so the ECM does not control the alternator anymore. My friend is a master mechanic and did that to his customer car. No more battery light and everything is ok

2 out of 2 people think this is helpful.

Your Answer

Add photo

Related Questions

Trooper

Looking for a Used Trooper in your area?

CarGurus has 128 nationwide Trooper listings starting at $2,595.

ZIP:

Search Isuzu Trooper Questions

UK Questions

Are you a UK consumer? CarGurus now has a discussion forum in the UK.

Isuzu Trooper Experts

#1 N8dogg
N8dogg
Reputation 580
#2 tennisshoes
tennisshoes
Reputation 370
#3 DerekW85
DerekW85
Reputation 180
View All

Related Models For Sale

Used Toyota 4Runner
341 Great Deals out of 20,329 listings starting at $1,250
Used Isuzu Rodeo
314 listings starting at $2,442
Used Mitsubishi Montero
161 listings starting at $1,295
Used Nissan Pathfinder
504 Great Deals out of 24,525 listings starting at $1,795
Used Toyota Land Cruiser
22 Great Deals out of 1,177 listings starting at $4,995
Used Jeep Cherokee
335 Great Deals out of 52,604 listings starting at $2,200
Used Toyota Tacoma
712 Great Deals out of 32,122 listings starting at $2,000
Used Jeep Wrangler
488 Great Deals out of 17,959 listings starting at $2,950
Used Jeep Grand Cherokee
1,001 Great Deals out of 65,972 listings starting at $1,500
Used Ford F-150
3,217 Great Deals out of 205,088 listings starting at $1,779
Used Mitsubishi Montero Sport
343 listings starting at $2,800