It was cold down here last night and there was ice on my car this morning (rare for NC). I got in and warmed it up and turned on the rear defroster. ( the ice was really slush ) I drove for about 15 minutes and when I looked down after about 10 minutes of driving the rear defroster was off. Does the car do this automatically?? I know that when the car is turned off with the rear defroster on it is turned off when the car starts.

is this normal?? never needed to use the rear defroster before

Yes, it turns off automatically. But if you are going fast enough it stays on, I don't remember what the speeds where though.

i thought it was a 10 or 15 minute thing...

Look in your owners manual, it will tell you about the defroster.

Yes, I think on the older Bonnevilles (92-99 not sure about all trim levels either) the rear defroster drops out after approximately 10 minutes or so regardless of speed. On the newer Bonnevilles (2000+) if the speed is maintained over 30 mph, the rear defroster stays on indefinitely.

IIRC, the first press gets you 10 minutes; every press after that in the same driving session gets you 5 minutes each.

That'* correct, Andy. keeps the grid from burning out. After you turn off the car and restart, you're back to a 10 and subsequent 5'*. We do know our 93'*, don't we

Cool...so after the initial push...I get 5 min more for each additional push...great news...its cold here...

Watch your outside mirrors as well. Depending on the model and trim level, you should also find that the outside mirrors defrost along with the rear window.

Hey, waitaminnit, I got the book here...

Actually there'* no RPO code for heated mirrors; they're lumped in with the rear window defogger. Looks like if you have a rear-window defoggers, you have heated outside mirrors as well.

I dont think that is true. I know that My mirrors are not heated and I have the defroster. I think the some SSE and SSEI have this option. I am positive my SLE dosent have it