Isuzu Trooper Alternator Problems

toomean2toomean2 Member Posts: 1
I have a 95 isuzu trooper type s a/t recently my batter went bad and was since replace. however it drained quick and would not hold charge. i replaced the alternator and my lights are still dim and only running at about 11 to 12 volts while idle and driving. we tested the alternator but it is fine at 15 amps. anyone have any ideas what is causing this? please help


  • matausmataus Member Posts: 43
    I really hope someone can help me with this. I have a 1991 Isuzu Trooper with 2.8 liter/5 speed manual trans. I love my Isuzu! It kicks butt! The problem I am having is this...

    I keep going thru alternators. In the last few months, I have gone thru 3 of them. It's really starting to get frustrating. When they start to go bad, I notice a humming squeak like noise. Like the brushes are rubbing inside. Then from there, I notice my truck having more difficulty in starting from the lack of power in my battery. It is obvious that my alternator isn't proving the power to my battery to start like it should. I did replace my battery with a new one, and still the problem persists. One thing I did notice is that it is more relevant in the cold. Also, when my alternator starts to go bad, my headlights, dash lights, any light, starts to randomly dim/increase up and down. I do have fuses attached to everything powered by the battery. So to protect against surges or whatever problem may arise power wise. I am thinking that if there is a short somewhere causing my alternator to go bad, wouldn't a fuse blow?

    Anyhow, thank you for taking the time to listen what I have to say. If there is anyone out there who can help me with this, it would be greatly appreciated...
  • boxtrooperboxtrooper Member Posts: 843
    It sounds like you have an excessive load on your alternator that comes and goes when it pleases. I would find all the wires that are visible, start near the alternator, search the engine compartment then look under around the frame all the way back. Since you did not mention smelling smoke or roasting plastic wire insulation, I expect the problem is not inside the Trooper. Do you have a trailer hitch wiring adapter? Those can sometimes go bad and cause excessive loads and strange behavior of other lights in the dash etc..
  • atfdmikeatfdmike Member Posts: 414
    Hi, All the symptoms you describe all relate to the alternator going bad and the resulting low voltage. There were two alternators used, one with higher output than the other. You want to make sure you are getting the right one, or upgrade to the larger alternator if you find that there are no other problems like Boxtrooper refers to. Make sure when you attach the battery wire to the alternator that the terminal is not touching the alternator housing after you tighten it. Good luck
  • matausmataus Member Posts: 43
    Thanks a bunch for replying to my post.
    There were a couple things I did forget to mention. When my alternators went bad, I would have them checked at my local auto store for amperage. One thing that was noticeable, is that one alternator had lover voltage compared to the other that had more voltage then the norm. I do disconnect all the wires from my battery before I add leads/grounds to my alternator. I do have a fairly nice stereo with a somewhat high power amp attached to it. Is it possible to add a higher power alternator to my truck?

  • boxtrooperboxtrooper Member Posts: 843
    Here is a place that specializes in after market alternator upgrades, I have not used them, but they have a nice website:
    Also, a bigger capacity battery might help prevent loading the alternator especially if the load is off more than on, here is a battery that will fit the Trooper battery box and has something like three times the cranking amps and and can be used in deep cycle mode without damage:
    Note: Measure your battery box before ordering, I have use the Lifeline battery and an inverter to let my kids watch two movies and then the news while powering a fish aquarium every night for a week after a big ice storm.
  • toolguystevetoolguysteve Member Posts: 2
    on the back of the ingersol alternator are the battery post, and one post that is labled W and the other post is labled D+. on the new ford alternator there are three posts as well but these are battery, P and the other is an R which match up? does the wire that went to the W go to the P or the R? and the same for the wire that went to the D+ does it go to the P or the R? thx steve
  • paisanpaisan Member Posts: 21,181
    um this is the Isuzu board....

  • toolguystevetoolguysteve Member Posts: 2
    sorry... first time user of this site. where do i go for this problem?
  • paisanpaisan Member Posts: 21,181
    Hmm try the Ford section, should be under the pickup-section.

  • tidestertidester Member Posts: 10,059
    You may also want to try Got a Quick, Technical Question?.

    tidester, host
    SUVs and Smart Shopper
  • cacianocaciano Member Posts: 1
    i have 2001 trooper 4w limited edition.Today i was driving my truck and it look like my transmission failed because while driving i started noticing that when i pressed the gas it would make a noice like if the transmission dragged a little,and it would do it only when you came to a complete stop and would try to get speed again so at that time i tried to check the oil level but couldnt fing a stick gage.i also notice a light saying check transmission came up and turn off and did not come back on it just gave me a warning. I look at the bottom of the truk i found some transmission oil leakage very minor,it covered the pan but not leaking in excess or anything do you think is a transmission failure or maybe it could be a broken seal or not enough fluid in the pan problems with reverse gear or any other gears just at the time of punching speed.
  • paisanpaisan Member Posts: 21,181
    You probably lost enough fluid to overheat it. I'd get it drained and filled and go from there.

  • geagleburgergeagleburger Member Posts: 1
    My 95 Trooper (3.2L DOHC) was freaking out on me. Ocassionally the check trans lights would start flashing along with the air bag light. The tranny would barely start moving and the alt. gauge was pegged at 16 volts. It would dissappear when slowed down (engine RPM's were down) then start running perfect.
    I changed the alternator and it cured everything. Too much voltage was being produced. I had a power steering leak which covered the alternator in muck & goo and probably led to it's demise.
  • atfdmikeatfdmike Member Posts: 414
    Yeah, my first alternator gave me fits too but once I changed it and cleaned up PS it is fine.....knock on wood!
    Welcome to the forum, it is a good place with nice people...but then, we all love our Isuzu's, don't we?
  • bushwacker1bushwacker1 Member Posts: 2
    Wow, a site for Troopers! Fantastic.
    drove home one night and my lights started to go bright and dim as I drove and reved the engine but the next night and there after they ran steady...until it rained, and all my dash lights come on, then the engine stalled and I blew out the Fuel Pump relay.
    Charged, dried drove and next rain, all the dash lights came on and it just eventually died
    To check for a short, I have disconected the NEG and attached a test light which did not light so I assume there is no short. I hosed the car from hood, tested again, still no sign of short.
    Attached the NEG and a voltmete: Battery still at 12.67
    Started the engine. Still 12.67 Reved the engine, no change
    Turned on lights, 12.14
    Turned of engine, back to roughly 12.6~
    Also, when I reved the engineI noticed a "clanking sound' coming from the ALTERNATOR area but couldn't be possitive.

    Does it sound like a bad alternator to you?

    Thanks for your help
  • atfdmikeatfdmike Member Posts: 414
    Yes, I would say that your alternator is bad. Once you have changed the alternator, hopefully the clanking will be gone. HOWEVER..........if not, then I would check all the belts to make sure no chunks are missing or flipped. If it is a true clanking sound, you may be able to isolate it by carefully using a long screwdriver by placing the tip on various engine parts and placing your ear on the handle .....the sound will be maginified and you can work your way to where it is loudest. I am thinking you have a 4 cylinder, so if you don't know the history, you could have a bad timing belt, or tensioner bearing, or other part that is bad. I think the timing belt is only good for about 60000 miles on your trooper. The clanking sound is usually a symptom when the hydraulic tensioner is bad. I am more familiear with the V6 though.
    Let us know what you find and keep us posted! Good luck and WELCOME to the forum! Lot of nice people here that like to help.
  • friedrickjoelfriedrickjoel Member Posts: 1
    geagleburger, I hope you can help me out. I seem to be having a similar problem. My 94 Trooper died one day, took it to NAPA, they said it was probably the alternator. I noticed some goop all over what I believe to be the power steering pressure hose.

    Did you figure out that all the goop from the leak caused the demise of your alternator? Did you replace the alt and p/s hose? Any info or advice you have would be greatly appriciated!
  • atfdmikeatfdmike Member Posts: 414
    Hi, thought I would offer my 2 cents worth here. It is a pretty common complaint that PS oil leaking onto the alternator due to its location underneath is why they fail. Given the Isuzu propensity for strange electrical problems, it is wise to replace the hose or the washers at the joint if that is where it is leaking. Getting a good name brand alternator or a reliable rebuild on your old one is important too. Seems like a lot of owners that get the neighborhood part store rebuild have problems earlier on than those that go with original or Bosch. HTH One guys opinion!
  • utrooperutrooper Member Posts: 2
    Hi all,

    Glad to find fellow Trooper fans! I have a 95 Trooper LS with 210K miles on it. Driving today the "check transmission" warning light started blinking while we were driving at a slow speed. After I stopped and read the owners manual, sure enough I had to start in L and manually shift to get home (thankfully only a few miles). Apparently the computer when sensing a problem automatically bumps you into the manual mode. I checked the level and color of the transmission fluid and it was dirty and seemed low which leads me to believe it just needs a flush (I have had the car for almost 10 years and don't recall ever doing this). This is our first "problem" with the car since we have owned it and I am hoping it is only the transmission fluid. Any suggestions or other ideas? Thanks!
  • kayreenkayreen Member Posts: 6
    Hi, my trooper 3.1td 1998 has been doing odd things! Went out got back in the car turned the key just clicked. Tried jump starting, no luck. Called out a mechanic started car but batteries very low in charge, meter had said 8 volts previously. Charged up batteries started the next day. Yesterday got in turned key nothing! I suspect alternator. Mechanic came out again brought auto electrician alternator seems to be charging! I use my car for going up and down to farms. Could wet and crap have got in and be discharging the charge from the alternator? If I get a new one I have been told to make sure I get the right one as otherwise olil pipes will not match up? Help!! I tow horses and cannot have it break down on me with them.
  • atfdmikeatfdmike Member Posts: 414
    Generally speaking,it is not a good practice to get a flush if the trans has that many miles. It seems to lead to problems like sticking valves and future problems, since a flush has a tendency to loosen deposits but not get them all out.. It is better to do a filter change and fluid change and do it again in 10,000 miles. You did well to get that many miles with no attention. HTH
  • atfdmikeatfdmike Member Posts: 414
    One way to determine if it is the alternator on a Trooper is to see if the heater/AC blower turn on while the engine is running. If it does not, then it is alternator. Japanese wired the system so if alt quits, most unnecessary accessories don't work. The alt is mounted in the worst place,down low on engine, not hard to change but it is exposed to water from splashing and mud since it is so low. Usually not a problem unless you go offroad or are in mud and rain a lot. There is a shield on it, but it is not very big. If the engine starts, the indicator lights often light up illogically if it is the alternator too. Brake warning, ABS, etc light up too.
    Rebuild alts are fine if OEM or Bosch. Still not cheap, but at least they work right with Isuzus. HTH one guys opinion.
  • kayreenkayreen Member Posts: 6
    Many thanks for that, my AC/Heater does not come on right away I have to wait a while before it comes in. Had a look at the terminal on the alternator and a wole load of rusty mush came out. I suspect that it is the problem. We have wet cold here in Scotland!! Many thanks again. Will change it.
    Cheers Kayreen
  • bushwacker1bushwacker1 Member Posts: 2
    I had the same issues:
    replaced starter first
    then battery & all cables....
    worked for a white then it rained and my RELAY SWITCH blew.
    I replaced it & the alternator and have had no problems since.
    NOTE: My Trooper sat for days on end and still started up
    NOTE: I have since given it to my nephew in college and back hills bike riding and it continues to start right up.
  • kayreenkayreen Member Posts: 6
    Many thanks I am going to replace the alternator!! I cannot have it deciding when to go and not go!!
    Best wishes
  • izzbo1izzbo1 Member Posts: 1
    I have an 86 trooper I just bought yesterday. brake and alternator warning lights are on intermittantly when running. When they are on, my tester says the alternator is only putting out 11 volts. When/if they go off, my tester says it is putting out 14 volts. Supposedly the alternator was JUST rebuilt (days ago). Is tthis simply an alternator problem or could it be something else in the system? how can I track it down?
  • atfdmikeatfdmike Member Posts: 414
    It sounds like a bad alternator to me. Even fresh out of the box, some alts are not right. There are diodes in the alt that can be bad and the alt will still test as OK. Getting a quality rebuild on the alt is generally ones don't seem to hold up or work at all in many cases.
    Your year has two style of with IC regulator built outside. If your voltage regulator is outside, that is likely the cause.....otherwise, you seem to need to replace the alt. Make sure though, that the ring terminal on alt is not close to or grounding on alt case. Very commom problem when installing and tightening terminal nut. If it is OK, then above would apply.
    Part nos. at HTH One guys opinion
  • dochodesdochodes Member Posts: 2
    Had a world of pain with my Troop which developed a weird engine fault which I assumed to be fuel related. Would run fine then start to shudder and some time stall at low revs. Had the fuel pump tested by bosch specialist who then fitted a new actuator, same problem was back within 2 weeks. reputable garage so they refunded me and replaced original actuator. All fuel lines checked and even tank replaced. It may be a coincidence but I have replaced the battery twice on this troop and with a new battery there seems to be no noticeable engine issue. Then it comes back after a few weeks. Vehicle has been used very little over last couple of years (hence the new batteries, I didn't keep them charged up!) My gut tells me that the engine/fuel problem could just be an underperforming alternator and when power drops fuel issue appears. Any thoughts anybody???? HELP!
  • dochodesdochodes Member Posts: 2
    does anybody have the tech specs of how the alternator should be perforning? I assume I can then stick a multimeter on there and check if its OK or not. Ive had two different opinions on its performance from 2 different engineers: RAC guy said alternator was not charging correctly, guy at the battery shop stuck his meter on there and said alternator was fine!. Ive also noticed that the tensioner is a pain in the [non-permissible content removed] on this vehicle, after tensioning belt is back to squeeling after just a few days. (belt is an original ISUZU part so I would expect to be correct size)
  • rb63rb63 Member Posts: 1
    alt bench test ok but drains battery when i installed it back on the vehicle
  • jostranderjostrander Member Posts: 1
    hi i have a 98 trooper 6cyl im haveing an issue with voltage spikes ,it spikes at 18 and above it blew the highbeams and put the tranny in limp mode . if i put the vehicle in park and turn off and on again its fine but will spike again it fluxuates alot and sometimes stays at 18v but will eventually drop and fluxuate more . i have put many new grounds all over the vehicle but hasnt helped ive cleaned all the plug connections i could find by tranny and engine . next is to replace the alt. but ive been told by many people that the alt regulator wont fluxuate like that its either good or bad no in between . if any one can help i would really appreciate it thank you, jason
  • atfdmikeatfdmike Member Posts: 414
    edited March 2011
    Most certainly a failing internal regulator will exhibit the behavior you are experiencing. It may be intermittent due to the different loads it is seeing, but should NEVER be above 13.6 (14) volts...if it is, the regulator/alt is bad.
    The only exception to this would be if you removed the battery and the alt was running the systems, in which case the regulator would spike all over the place as loads changed and it had no baseline 12 Volt signal from the battery. Never disconnect a battery from a running ECM controlled vehicle of any brand. It can have disastrous results.
    HTH One guys opinion.
  • trooper97trooper97 Member Posts: 3
    hi atfdmike,
    I'm experiencing pretty much what ostrander was with the voltage spiking to 16 but I also have the dash light all blinking on and off while it's spiking (I can here clicking as they do under the dash above my left knee) then it will return to normal but when I come to a stop the tranny starts like it's in third gear (very slow. it's an automatic) If I turn off the car and restart it, it drives normal for a while then will eventually Start all over again. Does this sound like the alt?? or Regulator??
    Anyone else Having this problem besides me and ostrander.
  • atfdmikeatfdmike Member Posts: 414
    Based on the symptoms you describe, and knowing that Isuzu's are very voltage sensitive, you really need to check your connections and vehicle grounds to make sure they are good. If they are and the intermittent problems keep happening, then you may have a harness that has a broken conductor/wire or the problem is the alternator/regulator. You don't say what year and model you own, but if a 97 Trooper, then the regulator is internal to the alternator, and you may wish to get a new one. Use caution in buying one as the unique construction of the alternator and quality must be good to insure the voltage and circuits work properly. There are many horror stories about new alternator problems or failures (I am one of those that experienced it) due to bad rebuilt quality or parts.
    HTH One guys opinion
  • trooper97trooper97 Member Posts: 3
    Thank's atfdmike, I think this will help. I'm taking it in today and will leave it with the shop for a couple of days to see if they can determine the cause. I'll let you know what I find.

    By the way it is a 97 3.2L Sorry about that.
  • trooper97trooper97 Member Posts: 3
    Ok I've had the Trooper back for a couple of weeks and everything is running great! So the alternator was the problem.
    Thanks for your quick response and help atfdmike.
  • atfdmikeatfdmike Member Posts: 414
    Great news! Thanks for posting your results, as it helps others down the road too!
  • trooperfan96trooperfan96 Member Posts: 1
    My 96 Trooper Se will not hold a charge. Mechanic replaced the alternator 3 times and none held a charge. This vehicle has been going through alternators every year and now none are working. Please help!!! It will indicate it is charged and shortly the battery is totally drained. :mad:
  • ynotnvmeynotnvme Member Posts: 2

    1995 Trooper LS 3.2 has what feels to be some sort of miss/hesitation and when and if I pull my 4 wheeler the transmission seems to go into creep mode after a while not want to shift and transmission light goes crazy. Also my dash/dummie lights are on (brake) and sometimes others. Alternator? Seems to test ok.

  • ynotnvmeynotnvme Member Posts: 2

    Nevermind....seems just like the same thing that Trooper97 was dealing with. I am just gonna replace the alternator!

  • steverstever Guest Posts: 52,454

    @ynotnvme, good luck please let us know how it goes!

  • Native71Native71 Member Posts: 1
    i have a 95 isuzu trooper 4x4. 6 cyl sohc. my battery was completely dead one morning so i tried charging it in the vehicle. when i attached the charger it imediately shorted out. i thought i traced the problem to the alternator. when i disconnected the positive lead at the alternator the battery charged back up. as soon as i touched the postive cable back on the alternator it shorted again. i purchased a new alternator. as soon as i attached the positive cable it did the exact same thing. i took the alternator and had it checked they said it was working properly. i made sure the positive cable was not shorting on the alternator housing. if anyone could help me i would very much appritiate it.
  • Crystalt84Crystalt84 Member Posts: 1
    Clicking noise is the lifters. It can be remedied with a cleaning but can get expensive. The 3rd cylinder keeps misfiring which has me replacing spark plugs more frequently. Could this be more electrical. The check engine light will blink and revving is difficult and will drop while going like 25-30 mph

    Alternator says ok during bench check but in vehicle says low. Can’t get warranty to replace it while they check int outside of car
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