Being in the cold MN climate during these winter months, I have to use the rear defroster much.

But after a 2-3 mile journey home from work, when turning on the rear defrost as i leave, after about 60-70% of the drive, it wont engage on again. Yes i understand it has to reset, but when i park, my power locks don't respond during this time either.

If i try keyless, i can hear the RAC module trying to fire the locks, but still nothing happens.

Any thoughts?

could there be a short on the defroster which draws too much current or overheats something and shut them out? way out of my knowledge but just a guess.

my car did it too...... just wait a few minutes and it will all work agian... watch out cause your power seats wont work either.... i would turn it on till it started to defrost then turn it off for a few then turn it on.... just dont let it turn its self off!!!!!

When my driver'* door lock didn't work, it was the lock assembly.

But I think this maybe a relay issue. The set behind the glove box.

I haven't noticed it before, maybe it happened last winter.

It'* been decently warm for winter, so not much rear defroster use till a month ago.

Rear window defrost is normally on a dedicated ckt. and not shared with anything else.

If I were in Florida...I could pull the correct year manual off the shelf and check. Off the top of my head...I'd agree with Mark.

I am having the same problems.... If I start the car, hit the rear defrost, 90% of the time door locks and power seats will not work. If I shut off the Rear Defrost, within minutes I have power again. Is this a possible overheating of a circuit breaker or a common relay within the rear defrost. Even though the button shows that the rear defrost is on, it is NOT functioning. ZERO power to the rear window. Any help would be great!!

You might check the ground connectors along the driver'* side and passenger side or passenger side. Other posters have shown these.

It could be the defroster causing corrosion problem on the ground buss bars losing ground.

On a 98 H-body I currently have a defroster that affects the radio antenna that uses the grid for signal. It probably is grounds at the antenna box in C pillar but could be elsewhere. I turn on the rear defrost and good radio signal returns.

I had a problem with 93 H-body occasionally losing control of the manual air conditioning control and the unit went into defrost and AC was turned on. At the same time automatic door locks didn't work.
After some time both would work again.

I figured out it was grounds but I had traded the car before following up. I rarely used the rear window defroster so it might have had symptoms but I never connected them.