, Salem, MA

August 10, 2013

'02 Avalanche has sensor issues

Auto Scanner
Larry Rubenstein

---- — Q: I have a 2002 Chevrolet Avalanche. The rear knock sensor light, p0322 has been coming on for a while. I bought two new sensors and a wiring harness. I took off the intake manifold and changed them both. After a couple of days, I went to get my sticker, and both the front sensor p0227 and the rear sensor p0332 came on together. Now, this only happens on the highway after about three miles of driving. I disconnected the harness to the powertrain control module and found that it still comes on when driving on the highway at the same place from where I live. I checked the voltage from the PCM to the harness and found that I was only getting 7/10 of a volt instead of the five volts that I read it should be getting. Is there a problem with the PCM? I once had to have it cleaned.

A: You need to check the powers at the computer. Simply unplug the harness from the sensors and check the voltage at the PCM. If the powers are all good, then you just may need to check the wires for an opening where the wire may have chafed. If the signal coming out of the computer is also weak, then a remanufactured computer may be the way to go.

Q: Thank you for providing a valuable service for all of us in the motoring public. I have a question that I’m sure a lot of folks would like to see answered. I will soon become a “snowbird,” and I am thinking of leaving one vehicle in Florida and one up north in New Hampshire. I would like to know what services should be done to a car that will not be used for five to six months and any tips on the best way to actually store a vehicle. In Florida it would be garaged; in New Hampshire it would be outside. My present vehicles are an ’06 Chevrolet Impala SS, ’03 Chevy Tahoe and an ’04 Mitsubishi Spyder convertible.

A: First, have all the fluids either checked or replaced, then fill the fuel tank. Next, block off all the HVAC vents with some kind of tape (to prevent animals). Cover the air inlet at the filter to prevent animals from getting into your air intake system. Put a few bags of mothballs under the hood to further deter animals. Put the car up on blocks to avoid flat spots on your tires. I recommend removing the battery even though quite a few people do leave the battery in. If you do remove your battery, try to store it in an area free of sparks and fuel. It would be a good idea to put either STOR, or seafoam made for fuel management into your gas tank to avoid fuel separation and evaporation. The most important step of all is to keep a written list of your actions to prepare the car for storage so you can restore all components and not forget a very important item like the blocked air inlet.

Car Care Tip: When you’re working on your own car and you need wiring diagrams or instructions on how to diagnose or replace, check out for a low-price, full-access subscription for a single car. A single repair successfully completed on your own can more than pay for the price of the subscription.


Larry Rubenstein is a master technician who owns a North Shore service station. His column appears every Saturday. Write to Larry at The Salem News, c/o Auto Scanner, 32 Dunham Road, Beverly, MA 01915, or send an email to