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David, Mechanic
Category: Cadillac
Satisfied Customers: 1500
Experience:  Heavy Duty Repair Mechanic Extensive knowledge repairing and rebilding engines, transmissions
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cadillac catera 1999 Cadillac Catera gets a Service Transmission

Customer Question

1999 Cadillac Catera gets a "Service Transmission" light upon acceleration.
Submitted: 6 years ago.
Category: Cadillac
Expert:  David replied 6 years ago.
Hi thank you for your question hope this helps.

P1275 = Accelerator Pedal Position (APP) Sensor 1 Circuit
P1890 = Throttle Position Signal Input.

These codes tell you there is a problem with the Accelerator Pedal Position sensor.

You can test the Accelerator Pedal Position sensor. using a volt ohm meter.

The sensor is bolted to the Accelerator Pedal.

Hope this helps
Good luck

Edited by David on 11/4/2010 at 8:15 PM EST
Customer: replied 6 years ago.
I assumed the problem was a TPS instead. Your answer makes sense. Where might I find the pin out for my sensor to test it?
Expert:  David replied 6 years ago.


  1. Visually check the connector for cracks, or looseness, and that the connector is corrosion free.
  2. With the key ON, engine OFF, measure the voltage at Terminal B., the voltage should read about .5 volts.
  3. Operate the throttle smoothly to wide-open throttle (WOT), the voltage reading should follow the lever action, but not exceed 5 volts. If it does, or the voltage reading jumps, then replace the sensor.
  4. Check terminal A for a proper ground signal.
  5. Check terminal C for a 5 volt reference signal. If the signals are correct, the sensor is faulty.
  6. If the signals are not correct, check the circuits for continuity.
  7. If the circuits are not faulty, the PCM may be at fault.
Yes the Accelerator Pedal Position sensor is also called the throttle position sensor.

The TP sensor is retained to the throttle body by two bolts.
David and other Cadillac Specialists are ready to help you
Customer: replied 6 years ago.
It took a while to locate a new APP. Replacing it today fixed my issue. Thanks for the help!!!!!
Expert:  David replied 6 years ago.
Good to know.

Vary happy to help if there is anything more you need please just ask.