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Q: Door locks on and off on and speedometer dial fluctuates

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While driving several things start happening randomly: my door locks go on and off and the air-conditioning blows but it's warm air no longer cool and the speed on what are dial goes to zero even though I'm going 60 miles an hour and the first gear won't easily shift in the second. My dealer says it needs a new battery cable at a cost of $850. Do you think that is the real solution and is that a fair price?

My car has 170000 miles.
My car has an automatic transmission.

I would question the diagnosis for the dealer to show you the reason to get the cable replaced and why the cable is so expensive. Have them break down the parts and labor in the quote. I show about an hour of labor each for the positive and negative cables plus the price of the cable for your Avalanche.

There could be possible issues with wire harness chafing by the parking brake. Also you may have problems with fretting corrosion at the different modules throughout the vehicle that require each module to be disconnected and have dielectric lube applied on them to stop the intermittent connection issues.

If you’d like a second opinion on this, consider YourMechanic, as a certified technician can diagnose the issues with your electrical components and help you fix them accordingly. Good luck.

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