Throttle control codes wont clear, even though named parts replaced.
2009 Buick Lacrosse, 3.8 liter 6 cylinder Approx 2 years ago, new MAF and Throttle body with TPS. 2 weeks ago the check engine light came on with "Reduced Engine Power". Codes as follows: P0068, Map, maf throttle position correlation, P0102,Mass or Volume Air Flow A circuit low, P1125, Accelerator Pedal Position System, P2120, Throttle/ Pedal Position Sensor/ Switch D Circuit P2138, Throttle/ Pedal Position Sensor/ Switch D/E Voltage Correlation Since MAF and TB/sensor fairly new, I replaced the pedal. Cleared codes. Last 3 came back (no MAF codes). Checked all connectors for moisture and wire integrity. Did find some moisture in the multi connector (the one mentioned in a service bulletin), dried it out and used electrolytic grease. Tried to check voltage on TPS, but it has a 17 pin connector. Could not find a 5 volt input to the TPS. I found a 12 volt and a few under 5v (3.6v was strongest under 5). Cleaned up Throttle body and recalibrated TPS. Cleared codes, they stayed off while i test drove (approx 3 miles) and same codes returned with reduced engine power. Codes wont clear and R.E.P. light stays on. Live data indicates a discrepancy in my APPS voltages, but its a new pedal. Ive tried to recalibrate the TPS again but it didnt change anything. I cannot locate accurate info on the 17 pin connector. At $200 for a new TB/TPS and new pedal installed, i dont want to spend it if its not going to fix the problem. How can i trace out this gremlin? Where might i locate good wiring info on these sensors? How can i OHM out the sensors to determine if they are working? Would a diag comp scan accurately locate it and could it differentiate between bad sensors or /and ECU that needs to be replaced or reflashed. Truth is that this is still a nice car and i couldnt replace it for the several hundred this might cost. I dont mind spending the money, but i dont want to just randomly swap out parts without knowing that its going to solve the issue. Any help getting me in the right direction would be appreciated. Dale
