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General discussion

Engine light comes on at times in GMC van!

Mar 18, 2008 2:54AM PDT

Hello: This should stump quite a few as it has all of my mechanics who've attempted to fix it. Vehicle: 1995 GMC Vandura 2500 cargo van.305 cu.in.(FI) engine, automatic with 120,000 miles on the clock.Problem: Engine warning light comes on, but not all the time. Comes on usually after a large upward swing in ambient outdoor temperature, usually around the 32 degree mark (eg: day starts out at 10 degrees and all is fine. Then, when temperature warms up outside to approx. 32-40 degrees, the yellow engine light comes on). The light usually comes on when you start the vehicle, but sometimes comes on while driving. It makes the engine rev higher and shifts very roughly as the transmission goes to maximum pressure through default of the system. To get the engine light to go out, I stop the vehicle and restart it (sometimes over and over)until the light finally goes out and everything goes back to normal. It's very irritating, especially in Spring, as the outside temperature does its usual swings, which brings on the yellow engine light warning. I've had the van put on a code-reader, and it says the TPS is bad. I've installed two TP sensors as well as the wiring harness for the TPS, but still the problem persists! Okay, I give up! What is causing this problem? Anyone here had a similar problem and been able to fix it? I would dearly like to know as I've been putting up with this for over two years now. ANY help would be appreciated!! Thank you to all!

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