Ask the Auto Doc: Wire problems trigger warning lights

Because they flex every time a car door Because they flex every time a car door opens or closes, wires between the door and body of a car -- including the 2004 Jeep Grand Cherokee pictured above -- are very prone to become broken. Photo Credit: Chrysler Media Group

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Dear Doctor: I have a 2008 Chevy Uplander minivan that I bought used. There are intermittent warning indicators that come on showing the ABS, traction control and stability systems need to be serviced.  It took my mechanic a long time to figure out he needs to change the whole bearing assembly by the front left wheel. The part was changed twice last year. Each time the warnings cleared for a few months and then came back on. What is going on here? -- Max

Dear Max: The first step is to check the trouble fault codes and then follow them to the effected wheel. The wiring to the wheel speed sensors is very tight and sometimes pull apart. I have seen a lot of wire connector problems. As for a continuing failing ABS sensor and/or bearing, this is not very common, even with the use of aftermarket wheel hub and bearing assemblies. Your technician will need to road-test the van with a professional scan tool and monitor all of the wheel speed inputs to see the wheel that has the problem. -- Doctor

Dear Doctor: I have a 2008 Nissan Pathfinder 4WD with 104,000 miles. It has the 4.0-liter V-6 engine and after it's been driven awhile it grumbles and vibrates when stopped. I'm thinking it feels like the transmission. I really like the cab-on-frame truck, but keep worrying that I might be pushing my luck with the transmission. What do you suggest? -- Al

Dear Al: First, the SUV will need to be checked exactly when the vibration is present. I have seen many causes of vibration, including a harmonic balancer, engine mount, exhaust fault, and fan belt driver accessory. -- Doctor

Dear Doctor: I can't drive my 2001 Chrysler LHS in the dark because the lights flickering are very distracting and dangerous to me. The car has less than 30,000 miles and has been faithfully maintained by the dealer since it was bought. The dealership was sold and is under new ownership. I have taken the car in twice trying to get them to correct the problem, but the lights don't flicker there, as it happens after being driven for about 20 minutes. They don't have a solution. Can you help me? -- Maria

Dear Maria: A flickering light usually indicates a faulty alternator or poor electrical ground connection. I have seen a few faulty dash clusters and this is not a major expense to repair, if in fact, the dash cluster is at fault. You need to find a certified technician who can and will repair your car. Contact the local AAA office and ask for a list of AAA-approved shops. -- Doctor

Dear Doctor: I have a 2007 Mercury Milan with 55,000 miles. The airbag light showed up on the instrument panel. The dealer found that the passenger side seat rail needs replacing at a cost of $1,200 or the light will not go out. Any thoughts? -- Jerald

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Dear Jerald: The SRS airbag system is complex and has many safety features to prevent unnecessary deployment. There are many sensors in the system and they all have to work together. When it comes to diagnosing the system it takes a technician who knows and understands the SRS system. It is expensive and in some states the SRS system has to be functioning in order to pass state inspection. -- Doctor

Dear Doctor: My mechanic changed a catalytic converter in my 2000 Toyota Camry eight years ago. Every year my "check engine" light comes on and he gets it to go off for annual state inspection, but it always comes back on. He is baffled. Also, when I put on my rear window defroster, the radio becomes fuzzy. Could this be an electrical problem, not a mechanical one? -- Libby

Dear Libby: The "check engine" light can come on for many reasons and many systems. You must first find out the trouble fault code. If it is related to the catalytic converter, then the mechanic may have to revisit the replacement converter. Many independent shops replace catalytic converters with non-factory converters that will not clean the emissions emitting from the engine. I replace many catalytic converters, and on import cars the factory converter is a must. As for the noisy radio with the rear defroster on, have the technician check the ground connections at the rear window and body ground. -- Doctor

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