What does it mean?
P1722 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Automatic Transmission Diagnosis Input Signal Circuit High Input .
Symptoms
- MIL on with a transmission warning light
- Transmission entering limp mode with a fixed gear
- Diagnostic routines or self tests refusing to run correctly with a scan tool
- Poor or unpredictable shift quality
- Related communication codes stored in other modules
- Intermittent behaviour that follows vibration
Likely causes
- Open circuit on the diagnosis input line, so the module sees an unloaded high level
- Short to battery positive on the diagnostic input circuit
- Terminal corroded or backed out at the module or the diagnostic connector
- Failed sending module or switch that should pull the line low
- Harness damage left behind by earlier repair work or an accessory installation
- Poor ground reference for the circuit
- Transmission module input circuit fault
How to fix it
- Read live data and confirm the input is genuinely sitting at its high limit
- Check the wiring diagram to identify what should be pulling this circuit low during normal operation
- Disconnect the module and test the circuit for continuity and for a short to battery voltage
- Inspect both connectors for corrosion, moisture and pushed-out pins, then clean and reseat them
- Voltage drop test the transmission module ground circuits
- Wiggle-test the harness while watching live data to catch an intermittent open
- Repair the damaged wiring, and suspect the module input only after the circuit and the driving component both test good