Voltage drop during acceleration... '96 3.2l sohc
 

So the other day I noticed my dash lights dimming during acceleration and sure enough, I glanced over at the gauge on the dash and it would drop to 12 while I accelerated, once I took my foot off, the reading went back to normal...I have never seen this before, on anything.......Its a 1996 (10/95) Trooper 3.2 sohc with 181k miles on it. Also has a brand new alternator from NAPA that has less than 150 miles on it. I took it to NAPA and had them run an electrical test on it, it passed on everything from the battery to the alternator... Everything is working just fine, just the movement on the gauge.Also I did notice that the lights dim/gauge moves in rythym with the turn signal. That I have seen before on other cars, is this connected to the acceleration things too?Any guesses?

The alternator should be producing more current when accelerating because of the higher RPMs. The opposite of what is happening to you.
Does it have an external voltage regulator or is it in the alt?

Im pretty sure that it is an internal regulator...

I cannot be certain until I read through my repair manuals, but are most cars of this age and newer all internally regulated?

Yes, usually they're internal now, just thinking of possible answers to your problem.

My trooper has the same problem. Did anyone find a solution?

NO...

But, it never really caused any problems.

I guess its more of an anomaly than a real problem.


Did yours ever become an issue? I cant say because I ended up selling mine.

Seriously, lots of people rest their foot on the clutch without realizing. It's a one way ticket to a burned out throwout bearing, not to mention new clutches much too often.

I have the same truck and the same thing happens. I did some research and found this is normal. The ECM tells the alt to stop charging during hard acceleration to lessen the load on the engine. I should have looked this up before pulling the alt and testing it.

Voltage drop during hard acceleration- '97 Trooper
 

I found this on another site. Does anyone know if this tech bulletin also applies to the '97 model (3.2 LX)? I just had new alt installed and they said the drop is normal?


1996 Isuzu Truck Trooper V6-3165cc 3.2L SOHC (6VD1)
SB96-04-L002
ISSUE DATE
FEBRUARY 1996
GROUP
ELECTRICAL
1996 TROOPER (UX) AND RODEO (UC) VOLTMETER NEEDLE
DROP DURING HARD/QUICK ACCELERATION
AFFECTED VEHICLES
1996 Trooper (UX) and Rodeo (UC) models.
SERVICE INFORMATION
On all affected vehicles, the instrument panel voltmeter needle will drop during hard/quick acceleration. This voltmeter needle drop is normal and is not indicative of a condition requiring repair.
1996 vehicles are equipped with an alternator that is designed to stop charging during certain engine speed modes in order to lessen engine load. At idle, the alternator will output approximately 14.3 volts. During a slow/steady acceleration, the alternator will remain at a 14.3 volt output. However, during a hard/quick acceleration, the alternator output will drop to 12.7 volts. The alternator will continue this 12.7 volt output, until the Powertrain Control Module (PCM) detects a drop in engine speed, at which time, it will return the alternator output to 14.3 volts.

I just wanted to agree with Trooper012's information. I have been a mechanic for 40+ years and still own a bunch of Troopers. I was going to give the same information. I think when they went to the 3.5 motor they dropped this idea as they had more power. The voltage was controled by the TPS and manifold vacuum to give that little extra power and once the load was dropped everything goes back to normal.