I need somebody who knows Bonnevilles really well. I have a 95 Bonnie SSEi and my heater core went out. I took it to the shop and they replaced it. I took it home (after a week) and drove it for two days with no problems. I left it parked all day Sunday and when I went to go to work on Monday, the battery was dead. No lights were left on or doors open I'm sure. I was jump started, but it took quite a few minutes for it to start up. When it did, my gauges keep reseting themselves. I drove it to work (20 miles) and the gauges (all of them) keep reseting. I bought a new battery, thinking that was the problem (I bought this car used a year ago). Although the car started right up, the gauges keep reseting. I took it to the mechanic that night and by the next morning the battery was dead again. He has looked at all my wires, my altenator and is scratching his head. I haven't had my car in two weeks, and I can't afford to take my car to another mechanic (I am a sole provider of two kids and layed off husband). :( I have looked at other posts, and have come up with the "cluster" that might be the problem, but my radio works, along with my seats, windows, etc. Could that still be a problem.
Please, Please, I need somebodys' advice.

Hi Misty, Welcome to The BC. It seems the Day Shift Electrical Gearheads have gone home for the day so I'll try to help. When your mechanic looked at the wires in your car, did he look at all the ground connections to see if there was any corrosion around the terminals and try to clean them? Did he look at the connections to the starter to see if they were clean? Sorry I can't be much more help at this time. Hopefully the Electrical Engineers here will chime in soon. Good Luck.

A Parasitic Drain Test on the battery would be in order. Ask your mech. to do that. Something is pulling that new battery down overnight. He should be able to localize the faulted ckt./ckts.

could be the ELC draining the battery if there is a leak in the system

Thank you all for your advice, it is well taken. I have wrote down what you think could be the problems and my husband is calling our mechanic to check it out. I believe that he has checked all the wires, but I don't know about checking for corrusion. Could there be specific wires that could be freaking out my gauges? I'm just tring to narrow down the search. My mechanic hasn't dealt with a car with this much electrical gadgets. Right now he is waiting on a complete wire diagram on my car. The one in the Chiltons book was not good enough, would anybody have that? I hope that if there are is any more advice that can be given, I would appreciate it.
Thanks again,
Misty

Everything was fine with the electrics before you had the heater core replaced?

The mechanic has pinched some wires near the core as it is under the dash where all your gauge wiring is. Have him go back over the dash wiring and look for a pinched cable.

Yes, I had no electrical problems, especially with my gauges (except my oil gauge and the compass stopped working) before the heater core. My mechanic said that he took out the dash again and went over all of the wires, he thought he might have accidentally put a postive to a negative (accidents happen right?). but could find nothing. I don't know if he looked around the core part.
Thanks Pontiac Dad.

Yes, there are a lot of relays and fuses up there. You could check for corrosion at the battery wires, too. And you should also try the parasitic drain test to focus on the cause of the drain.