HossPete
TYF Newbie
I have an '05 Yukon with 98,000 miles. Recently, we had the check engine light come on. Checked code, and it was bad knock sensors. Truck ran okay for awhile, then one morning, the battery was dead and it ran like crap. Like it was running really rich - you could smell the fuel in the exhaust and see it smoke. I took it in to be checked.
The battery tested fine, the alternator tested fine. Then he found a bunch of water on the top of the engine for some reason, and it had shorted out the knock sensors. Replaced them. Drove great. Until he turned on the AC...
Suddenly, it started running like crap again - he thought it felt like "limp mode". Pulled it back into the shop and turned it off. The secondary fan that kicks on when you turn on AC kept running... would not turn off. We had found our dead battery culprit. Switched out relays and fixed that issue. But not the issue of the activation of the fan causing it to run like crap. If you leave the AC off, it runs like a champ, but as soon as you turn on the AC, and that secondary fan kicks in - boom...
Any ideas out there? Is it just a short in the system, or is there something bigger we should look at? He is stumped - we've called a couple of other mechanics and they haven't heard of AC triggering limp mode either.
It's Nashville...it's 100 degrees...need some AC!! Help! Any ideas?
The battery tested fine, the alternator tested fine. Then he found a bunch of water on the top of the engine for some reason, and it had shorted out the knock sensors. Replaced them. Drove great. Until he turned on the AC...
Suddenly, it started running like crap again - he thought it felt like "limp mode". Pulled it back into the shop and turned it off. The secondary fan that kicks on when you turn on AC kept running... would not turn off. We had found our dead battery culprit. Switched out relays and fixed that issue. But not the issue of the activation of the fan causing it to run like crap. If you leave the AC off, it runs like a champ, but as soon as you turn on the AC, and that secondary fan kicks in - boom...
Any ideas out there? Is it just a short in the system, or is there something bigger we should look at? He is stumped - we've called a couple of other mechanics and they haven't heard of AC triggering limp mode either.
It's Nashville...it's 100 degrees...need some AC!! Help! Any ideas?
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