What does it mean?
P1772 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: TP Sensor Signal To TCM Circuit Malfunction (Shorted) .
Symptoms
- MIL (check engine lamp) is on, often with other sensor codes if the shared reference is involved
- The transmission behaves as though the pedal is floored: very late shifts and permanent kickdown, or the opposite if the signal sits at zero
- Harsh, hard shifts and high line pressure at light throttle
- Reduced power mode on vehicles with electronic throttle
- Poor fuel economy and rough part-throttle response
- Transmission drops into limp mode and stays in one gear
Likely causes
- Signal wire shorted to ground where the harness has chafed against a bracket or body panel
- Signal wire shorted to a voltage source, pushing the reading permanently to full throttle
- Throttle position sensor with an internally shorted resistive track
- Water, coolant or transmission fluid inside a connector bridging adjacent pins
- A damaged 5 V reference shorted to another circuit, dragging several sensors with it
- A poor previous splice or degraded tape repair in the loom
- Damaged input stage in the TCM (transmission control module)
How to fix it
- Look at the live throttle value with the ignition on and the pedal untouched; a stuck high or stuck zero value confirms the short
- Unplug the throttle position sensor: if the reading changes, the sensor is shorted internally
- With both ends disconnected, check the signal wire for a short to ground and for a short to battery voltage
- Inspect connectors for moisture, fluid wicking and green corrosion bridging pins, and check other sensors on the same 5 V reference
- Inspect the loom along its route for chafe points, especially at brackets and body pass-throughs
- Repair the short or replace the sensor, then verify a clean full sweep in live data before clearing the code