Voltage dropping

Hello,

I recently replaced the alternator on my 93 3.2L Rodeo 4x4. The gauge now shows +14V. I notice when I do anything electrical (turn on the rear window defrost, lights and even signal lights) that the voltage drops down to 12 and then back up to 14. With the signal light it drops as the light goes on and just goes back and forth (the gauge). Does anybody elses gauge do this? I've never seen this in any other vehicle and i'm wondering if its a short or is the gauge really that sensitive?

Thanks

Did you use a cheap aftermarket alternator? That could be the culprit. You might see the needle move ever so slightly when using the power windows or such, but a dip from 14 to 12 just doesn't seem right. Mine doesn't do that. Many people have good luck with a Bosch brand.

Well I couldn't get one from around here and they wanted $500+ bucks for it so i opted for a ebay one. Its not like it is really doing anything bad, i'm just wondering if anyone else has the same issue. Interesting.

It's not doing anything bad.....yet!!

Seriously, your truck may very well kill that one off in short order. Start saving for a GOOD alternator, the best you can buy, seriously, or you will keep replacing them every few weeks.

You can order one off from autopartswarehouse.com for less then $500; but expect to pay around $175+ for a good one.

Look into Bosch, Hitachi, Oem Isuzu, or Napa.

I repeat do NOT waste your time/money on just any alternator, these trucks LOVE their voltage and will kill a weak one in good time.

I always thought it funny how my chevy trucks could run on left over, cranky old alternators for years, and my Isuzu trucks would chew them up and spit em out in a day or two. Just the nature of the beast.

No, that's not normal, before too long you're bound to see your battery light come on and stay on; meaning the truck's not getting enough charge.

Your alternator WILL decrease it's volts however, when your truck lights are off and you hit the throttle - this truck IS designed to decrease it's volts when doing this, but only for a second or so....but it should NOT be dipping it's volts if lights are on, radio's turned on, etc.

Mine will occasionally dip it's volts if I'm putting up a power window, OR if I'm sitting idle with my fog lights on - they suck up a lot of power.

If you have something that's stealing a lot of power, this would make sense to happen on occasion, specially if sitting idle....but should jump right back to 14V the minute truck hits 1,500-2k rpm's.

Well we'll see what happens with this alternator I guess. I'm planning on selling this Rodeo around march so maybe I won't have to deal with it :p

Has anyone had any luck rebuilding the stock one? I have it sitting around but I couldn't find any rebuild kits for it...

Thanks for the replies!

If you do sale this truck and don't replace the alternator before then make absolute CERTAIN to tell the new owner that if he's having weird symptoms to check the alternator. I'm serious, these trucks can act weird, and when someone purchases an Isuzu and is not aware of this, it can make them spend hundreds of dollars trying different things out.

Also, where are you located at, maintenance history on the truck?? and how much would you be asking? .....I might be interested, I already have another high quality alternator sitting here.

Do you have any pics of the truck??

This potentially could end up a GREAT deal for an OEM reman. Alternator on ebay. The guy has 5 of them.

http://cgi.ebay.com/ebaymotors/ISUZU-ALTERNATOR-RODEO-3-2L-96-97-REMANUFACTURED_W0QQcmdZViewItemQQcategoryZ33573QQi hZ020QQitemZ300177184310QQrdZ1QQsspagenameZWDVW

I'm located in Alberta, Canada. Here is the alternator I picked up...

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=110135466906&ssPageName=ADME:B:EOIBSA:CA:11

One year warrenty on it so I would think it would be ok. It sucks that the stock alternator only puts out 60 amps too. I wonder how hard it would be to adapt another alternator. I might just upgrade the wires and if all else fails throw a yellowtop in there and call it a day.

Just because it has a 1yr warranty doesn't mean squat.

And, only throwing an upgraded battery in won't help either if the alt itself is to blame, upgrading the wires or the battery alone won't help.

Now if you do ALL of that, plus replace your alt, it'll last a long time. I have the HIGHEST cold cranking amp Interstate battery built, bigger then what's in my dodge diesel, in my Rodeo, along with all new ground wiring, Bosch alternator, battery grounds, etc....I haven't had a voltage issue in almost 4-5yrs.

Well I only say that because if it is a cheap rebuild and goes out then I can always get a new one.

The reason I would do the battery is to compensate for anything pulling a high "starting" amperage where the alternator can't supply enough amps. Take for example the rear defrost.

Now that I think about it, when I installed the alternator, the ground where pretty badly rusted and where it screwed down to the frame wasn't very clean. I'm going to have to go back in there and clean those up. I bet thats the majority of my problem.

And might also explain my misfiring problem and kind of hard starting. I think thats why isuzu's are so sensitive to voltage is because the wiring is minimal from factory and anything that restricts that more causes problems. We'll see after I upgrade it