What Does P1682 Mean?
The automatic transmission fuel injection signal to the ECM is reading abnormally high voltage. This signal coordinates transmission shift timing with engine fuel delivery.
Common Causes
35%
Damaged wiring harness with short to voltage between TCM and ECM
30%
Failed transmission control module sending incorrect high signal
20%
Corroded or damaged TCM connector causing voltage reference issues
10%
Failed ECM input circuit unable to properly read signal voltage
5%
Ground circuit fault causing voltage reference shift
Diagnostic Steps
1
Step 1: Locate signal wire between TCM and ECM and measure voltage with key on (compare to specifications)
2
Step 2: Disconnect TCM connector and recheck signal voltage at ECM side to isolate TCM vs wiring fault
3
Step 3: Inspect wiring harness for damage, especially near heat sources or moving components
4
Step 4: Check TCM and ECM connectors for corrosion, moisture, or pushed-back pins
5
Step 5: Monitor signal voltage with scan tool live data during various transmission operations
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
The automatic transmission fuel injection signal to the ECM is reading abnormally high voltage. This signal coordinates transmission shift timing with engine fuel delivery.
The most common cause of P1682 (Automatic Transaxle FI Signal A High Input) is: Damaged wiring harness with short to voltage between TCM and ECM
Typical repair costs for P1682 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause harsh or delayed shifts, poor fuel economy, or transmission protection mode. Vehicle remains drivable but transmission performance is affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1682 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control / Engine Management Interface
Difficulty
Type
Manufacturer
Recommended Tools
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