sundance - computer problems common?

On some models, don't know anything specific about yours, if the grounds can corroded it makes the car nuts. I would check for bad grounds first. Also a faulty battery or dirty terminal can make the computer act nuts.

41: Alternator field circuit open or shorted 16: Loss of battery voltage while engine running

These point to (surprise!) a problem in the alternator field circuit. Have you verified that the two field terminals are firmly attached to their studs on the back of the alternator? Tell us about this replacement alternator you installed: Was it used (probably fine) or a "remanufactured" hunkajunk from the parts store (definitely suspect)? If everything's OK in the wires between the engine computer and the alternator field terminals, then the computer's internal voltage regulator has probably failed.

Loss of voltage regulation function is pretty much the primary failure mode, and it's not incredibly common. You needn't replace the computer just because the voltage regulation has failed, however. Here. This sounds hokey, but it works just fine:

Take the easy and cheap way out. Use a NAPA Echlin VR1001 voltage regulator. The terminal on the end of the regulator's short wire The nut-and-stud terminal on the regulator body gets switched 12V from the ignition switch, and the terminal on the end of the new regulator's short wire gets connected (via a length of wire that you supply) to one of the alternator's two field studs. It does not matter which of the alternator's two field studs you connect this wire to. Then, using another length of wire, connect the *other* alternator field stud to ground. The vehicle's original two field wires get REMOVED from the alternator and taped off. (on some '90 and later vehicles, this will cause the "Check Engine" light to remain illuminated. Placing a resistor between the vehicle's two original field terminals prior to taping them off will prevent this.)

-Stern

It is a refurbed from an auto source store; I was warned that these are not very reliable by the mechanic that put it in but was not willing to pay his outrageous markup. It has a 5 yr warrenty which is good if this is the problem...except the labour is on me :) I have had several people check the alternator and they did poke around the wires, tightened the belt, etc. and didn't say anything. It will be removed and tested independent from the car tomorrow and I will know if I can eliminate that from my search in what is wrong or not!

Thank you for the suggestion. Reactions to computer problems so far have been - trash the car or buy a used one, no one has said anything about getting around it. This is my first vehicle so I know next to nothing about cars except what I learn when something goes wrong with this one, but I will ask whoever works on it to give your idea a try.

You've given me a little hope now :) Thanks again!

If it turns out to be a failed voltage regulator in the computer Daniels work around repair works perfectly. We did this on a friends car back last winter and haven't had a bit of problem since. He saved my buddy along the lines of $400 for a replacement computer.

You really weren't paying your mechanic for his outrageous markup (entirely).. Your paying for a quality product as compared to an inferior product. If its an easy to replace alt I use the cheapies myself but if you can't swap it yourself his labor charges to change it out when it fails are going to outweigh the value of that five year warranty pretty quickly.

Steve B.

I am expecting to have to do this at some time. How much resistance needs to placed across the two field terminals to turn off the "check engine" light?

Also, will a 1/4 watt resistor of the specified resistance work?

-Kirk Matheson

I never remember. Resistors are cheap, buy a few different values and try 'em.

Should be fine.

An easy sure bet way to determine the resistor value would be to measure the field current on a [correctly] functioning system and use ohms law to calculate what resistor is needed.

Agreed, except my mom and I got our nails dirty and now we can remove and replace the alternator ourselves :)

It wasn't the problem so we got a 20 dollar computer from a pick your parts place and the light went off, it worked fine. However, I drove the old computer home and it completely failed half way so my battery is dead :P

We tried a computer from a different source and rec'd the same error as my current one so I have a feeling this is more common than one might think.

80% of the cars of this engine size had their computers missing.

I just wanted to thank everyone who replied :)