Intricate Internal Computers Can Burn Out Due to Anything

December 12, 2009/Auto Sales Classifieds


Dear Doctor: I recently had the internal PCM computer board short out and fail on my 1998 Toyota Camry that only has 68,000 miles. The computer board was quite burned; therefore the mechanic could not find the root cause of the short. A used computer was placed in the car. So far the Camry is running well. What could have caused this? William
Dear William: The computers in today’s vehicles are very intricate. Computer circuit boards in any application will burn out from a short in the system it is connected to. It could be anything from switching solenoid, moisture, or a poor computer assembly weak, dirty solder joint, even a faulty electronic resistor or component from the factory. The used computer may still have the previous vehicle identification number and could present a problem at your next motor vehicle inspection. Make sure you have a receipt for the replacement computer, including the VIN number of the vehicle the computer was removed from.
Dear Doctor: I own a 2002 Ford F-250 pickup with the 5.4L V-8. I have a problem that no one has been able to repair. The problem is the ABS light flashes on and off, and then the speedometer stops working, and the engine temperature gauge goes to hot. What is going on? Harold
Dear Harold: I have actually resolved this issue on two trucks. I always check with the technician-support Identifix and Alldata web sites for any history of vehicle problems. Identifix did have a history on this issue. I followed the testing procedure as outlined, using our scan tool in the advanced setting to mode 6. The data on the scan tool found two fault codes: a misfire code and a loss of communication code. Next I followed the measured coil values and found one ignition coil out of specs. This faulty ignition coil was spiking the main computer ECU and causing the problem.
Dear Doctor: I own a 2004 Chevrolet Malibu with only 51,000 miles. The power steering stopped working. I shut the engine off, restarted, and the power steering came back. My mechanic said the repair could cost as much as $1,000. What’s your advice? George
Dear George: Without being able to actually see the condition, no technician will be able to make the correct assumption on what caused the loss of the power assist. If it happens again, get it to the shop while the power assist is not working.
Dear Doctor: I own a 2006 Jeep Commander 4.7L V-8 with the automatic transmission. The transmission has two filters: one inside and the other is a return spin-on type. When I took it in for service at 36,000 miles the dealer said they never change the spin-on filter because the transmission will loose its prime. I asked them to fill the filter with fluid before they install it. They declined. What are you thoughts? Jim
Dear Jim: We change only the outside filters and have never had any problems. I do recommend the use of the factory fluid and filter.

2006 Jeep Commander

Seldom do we drop the transmission pan to change the internal filter during regular service, unless factory recommended, or if the fluid is in poor condition.
Dear Doctor: I want to switch over to high-intensity discharge headlights on my 2002 Acura MDX. The shop wants to charge me $150. What would you recommend? Carl
Dear Carl: I would first check out simple replacement bulbs from some of the aftermarket companies. I have installed some HID conversions. We do use a lot of aftermarket replacement headlight bulbs. Companies like Sylvania and Piaa have DOT-approved brighter white lights that may suit your needs at a fraction of the HID conversion price.
Dear Doctor: I own a 2002 Ford Taurus that is inconsistent with the heat on the climate control. The air blow warm then goes cold. The local shop put in the correct thermostat, but still I have the same problem. Can you help? Howard
Dear Howard: Older Taurus and Sable models have a metal tube hose assembly from the engine to the heater core. I have replaced many hose assemblies and have reverse flushed the heater core. I’ve also seen a lot of very rusty cooling systems. Air entering the cooling system and old coolant is the number one condition that leads to restricted lines and the heater core. — Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician.

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Copyright, Motor Matters, 2009