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2002 Chevrolet TrailBlazer - Page 3 Questions & Answers
Shifting
Is your code reader capable of reading U, C, and B codes? The speedometer doesn't get it's speed reading from the wheel sensors. It gets it from the transmission. Not shifting past 2nd gear means your transmission is in "limp in" mode. It prevents shifting to avoid further damage. I see a transmission repair shop in your future.
Throttle position sensor
You should test it before replacing, just to make sure there isn't another problem you are missing. The computer only knows something isn't right.
I would do the testing before removal, as the tps is integrated with the throttle actuation motor. Remove the connector from the sensor and use an ohmmeter to check the sensor. Inspect the connector and pins carefully for damage. Also inspect the wires carefully. If visual inspection looks good, move on to testing. The sensor circuit includes three pins in the connector--pins B, D, and H in the lower left of the diagram below. Remove the rubber air pipe from the throttle so you can open the throttle by hand. Then connect your ohmmeter to pins H and D. Then slowly open the throttle by hand. The resistance between the pins should change continuously and linearly as you open the throttle by hand. If that test is good, move the ohmmeter probes to pins B and D and run the same test. If the sensor fails these tests, replace the whole integrated throttle control assembly. If it passes, the problem is probably with the connector or wiring.
The link below includes the procedure to remove the sensor.
Repair Guides Electronic Engine Emission Controls Throttle Position Sensor...
Thinking about buying a 2002 trailblazer LXT. It
This has variable valve timing. The VVT is run by oil pressure. A code can be the wrong viscosity oil, oil sludge or a bad VVT mechanism. The only way I'd even think about this vehicle is after it's been inspected by a mechanic. Skip that you you buy this vehicle at your own risk.
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