Strangest instrument light question ever...

Hello,

I have read a great deal of excellent info in this forum and I'm hoping someone can give me some insight on what is going on with my 1997 Isuzu Rodeo.

I purchased the Rodeo used a year ago with 80K miles and it has been running excellent. However, ever since the day I purchased it, the brake light has been on. It had obviously been on for the previous owners as well since there was electrical tape residue near it indicating it had been covered for some time.

Anyway, I took it home and cleaned the Emergency Brake switch contacts and discovered it was not the problem. I later learned that if I turn on my rear windshield wiper that the brake light goes off (and then it functions properly if I lift the Emergency Brake Lever up and down).

But wait, it gets stranger...

I recently replaced the alternator (it was truly bad and making a terrible racket). This work was done by a highly reputable shop, not by me. After it came back from the shop I changed the oil (as I always do every 3000 miles). After changing the oil I noticed that both my Battery light and 4X4 indicator light were on.

I perceived the battery light as meaning I needed a new battery since after all it was the original, so I bought a new Die Hard Gold. After installing the battery I still got the two indicator lights.

At this point I went back and checked everything I had done and realized I was a quart low on oil so I topped it off. This caused the two indicator lights to go out (the brake light is still on however).

This leads me to believe that my indicators are confused since being low on oil causes my battery and 4x4 lights to come on. I suspect that my Emergency brake indicator is actually trying to tell me something else since it goes out when my rear wipers are on and then functions normally for the duration they are on.

I should also mention that the 4x4 light that comes on when my oil was low doesn’t come on when I shift into 4 wheel drive. I had that switch replaced with no improvement.

Now the previous owner had a big sub woofer in it as I found heavy gauge amplifier cable under the back seat and audio input wires behind the dash (when I installed a CD player). I only mention this since it is electrical but I don’t suspect anything shorted out from his installation.

My experience with this dashboard is it is a large connector so I don’t suspect I have any wires out of place.

Could this be the ECM or some other electrical component I can check?

Is it possible to get trouble codes out of my Rodeo to see if the ECM is trying to tell me something?

Thank you very much for taking the time to read my story and for any information you can provide.

-=Alex

Alex- these are the classic symptoms of not running an OEM alternator. Newer (about 1995.5+) 3.2L's are EXTREMELY sensative to proper system voltage. Anything less than 14V with the truck running will give you the brake/4x4/oil and sometimes other simultaneous lights. An OEM alternator is $$$ (and hard to find) but the only way to cure this.
G/luck
Joel

Thanks for your reply Joel.

The Altenataor was big $$$, and my voltage readout on the dash gauge is close to 16 volts ( I know it's not accurate, but it's higher than when I started). I do not know if its an OEM or not. Would that come from the dealer?

I obviously was low on oil and that should send a trigger to light the oil indicator, but in my case it lit the battery and 4x4 instead. That leads me to belive it's a crosswire or other issue.

My other question for you is would the wrong altenator cause the 4x4 light to not go on when shifted into 4 wheel drive?

I'm not doubting you, I am just trying to understand it all better so I can go back to the mechanich and trouble shoot.

Should I go to the Isuzu Dealer?

Thanks again for your help.

-=Alex

I would start by reading the voltage with a volt/multi meter across the battery with the truck running. Search this forum for the symtoms you describe & you'll find lots of stuff. They are almost always caused by a faulty, or parts-store aftermarket/rebuilt/reman alternator.
G/luck
Joel

OK I'll measure the voltage at the battery with the engine idling. If I get 14 Volts or better should I assume the altenator is not the problem or is the OEM altenator magical? :-)

Also, is there a regulator or any other elctrical component in the circuit that could be bad that I should check?

Thanks for your help with this.

-=Alex