What Does P1771 Mean?
The transmission control module is not receiving a throttle position signal, indicating an open circuit. This prevents the TCM from properly controlling shift points and line pressure.
Common Causes
40%
Broken or disconnected wiring between TPS and TCM
30%
Failed throttle position sensor with internal open circuit
20%
Corroded or loose connector pins at TPS or TCM
10%
Transmission control module internal circuit failure
Diagnostic Steps
1
Step 1: Inspect TPS connector and TCM connector for loose, corroded, or damaged pins
2
Step 2: Check wiring harness from TPS to TCM for cuts, breaks, or pinched wires
3
Step 3: Test TPS output voltage at sensor connector while moving throttle through full range
4
Step 4: Verify signal voltage reaches TCM by backprobing TCM connector
5
Step 5: If signal is good at TCM connector, suspect TCM internal failure
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The transmission control module is not receiving a throttle position signal, indicating an open circuit. This prevents the TCM from properly controlling shift points and line pressure.
The most common cause of P1771 (Throttle Position Sensor Circuit Open to Transmission Control Module) is: Broken or disconnected wiring between TPS and TCM
Typical repair costs for P1771 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience incorrect shift timing, poor acceleration, or limp mode operation. Generally safe to drive short distances but performance will be compromised.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1771 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control System
Difficulty
Type
Manufacturer
Recommended Tools
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