Q: I have a '92 Dodge Ram 2500 with the Cummins diesel. Ever since the truck was new, the throttle-position sensor has been going out every 10,000-16,000 miles. The truck feels like it's freewheeling at 50 mph, and when I let off the gas, it will catch and go again. The part is expensive, and my dealer, like everyone else, doesn't seem to know what's causing it to fail repeatedly. Do you have any ideas?
A: An inaccurate throttle-position-sensor signal to the vehicle's computer can cause poor engine performance and erratic engine and transmission operation. You may very well be dealing with a poor electrical connection at the throttle-position sensor as opposed to the failure of the sensor itself. It's a somewhat common occurrence in automotive applications where an electrical component is replaced and the symptoms disappear for a period of time, whereas the problem was actually at the electrical connector and not the sensor. This occurs when the poor connection is disturbed enough during the replacement of the component that it temporarily reestablishes electrical contact, then corrosion and engine vibration will cause the problem to return in a short period of time. The TPS connector has shown a significant amount of problems on '91 and '92 Diesel Rams, and Dodge has come out with an updated TPS Wiring Assembly Package (part #4728883) to correct the condition. If the female terminals at the TPS connector are spreading or showing signs of corrosion, this package should take care of the problem. The installation will require rosin-core solder and heat-shrink tubing and should be performed by a qualified technician.
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If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sourceinterlink.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
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