This problem started a few months ago. We would be driving down the road and it just shuts off completely. We pull over and wait a few minutes before trying to start it and then it starts fine. We've done a lot of trouble shooting trying to find the problem. We eventually found that when we took the O-2 sensor fuse out that it would start but then would shut down again. We also found that when the a/c was on it would turn off and not start. When it shuts down or is about to shut off the high beam indicator light comes on (even when the high beams are off) and after a few seconds it shuts off. We found that in the fuse box some of the fuses were getting more power than they should have been. So we are thinking that there is a short to a ground? We opened up several wire bundles and haven't found anything yet. We are stumped at this point. Does anyone have any ideas? Help would be appreciated.

 

Sounds like the Ignition Switch is going bad to me? Use the Search here on the forum to get some more info about it. Also look at .Anatomy of the Ignition Switch By swartlkk Thanks to Kyle for all his hard work here on the Blazer Fourm.
Hope this Helps. T.J.

 

We already replaced that and it is still doing it. Thank you for the suggestion.

 

How much voltage is "more than they should be getting"?

 

We are getting 12 volts on the power side and the ground side of starter relay, headlight relay, and a few others.

 

Are you certain you are testing the proper terminals on these relays? The posts are cross corners from each other.

 

My dad is a retired aviation electrician and knows wiring very well. He has been working on his own vehicles for most of his life and is sure he is testing the right wires and connections.

 

Everyone makes mistakes. Better to double check and be sure than to think the problem is more than it is because you were too proud.

 

We have been working on this problem just about every other day for over two months we've tested it on all those days and still the results were the same.

 

But do you know what each of the terminals do? I hate to stick on a point such as this, but you may be digging into something that really is not wrong, potentially causing more problems...

I would test the output from your 'new' ignition switch to make sure that it is functioning properly. The link provided above gives wiring diagrams, etc so you can test the wiring at the main connector under the steering column.