My name is Craig and I live in Celina, north of Dallas about 45 miles. I'm new to the site and glad to find you all.
I have a 2005 Yukon. When I connect the battery my inside blower runs on high and the outside lights blink. I bought this vehicle wrecked with a salvage title and it didn't do this until I had taken everything off the front end (including removing the fuse box from the fender). I have everything back together including connecting all my grounds and its ready to paint, but I can't find the problem. Any suggestions, please?
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Updated info: I found a few others on the site with a similar blower experience and it seems best to replace the resister before looking any further. If it works it is a $21 fix. As for the lights this problem has not reoccurred.
Until you added the part about how "I had taken everything off the front end", I was going to suggest the speed control module.
If you have the auto HVAC (instead of the manual HVAC) a bad speed control module will react as yours does.
However, replacing the auto speed control module is more like a $100 repair. The large FET that ios inside the module is the part that usually fails. If you are any good with a soldiering iron, you can change it for $20.
Thanks for the suggestion. Where is the speed control module located.
I have also heard of relays causing the same problem. Any thoughts on the relay?
There are no relays involved.
The location varies depending upon models and years. My '05 Envoy had the blower control module mounted near the blower motor which was under the dash, behind the glove box.