P1621

DTC P1621: Immobilizer Communication Line Error

Wiring Diagram

Refer to Immobilizer Control System Wiring Circuit Diagram Immobilizer Control System Wiring Circuit Diagram.

Detecting Condition and Trouble Area






Troubleshooting



1.
Was "Immobilizer Control System Check" performed?
YES
Go to Step 2.
NO
Go to Immobilizer Control System Check.

2. Fuse check

Check fuse for ICM circuit.

Is fuse in good condition?
YES
Go to Step 3.
NO
Replace blown fuse(s) and then, check for short to power circuit.

3. Voltage check at power and ground terminal

Check power and ground terminal voltage of ICM connector referring to Testing and Inspection Inspection of ICM and Its Circuit.

Is each terminal voltage in good condition?
YES
Go to Step 4.
NO
Repair circuit.

4. ICM and ECM connector check

With the ignition switch at OFF position, check intermittent and poor connection of ICM connector and ECM connectors referring to Intermittent and Poor Connection Inspection Intermittent and Poor Connection Inspection.

Is each connector in good condition?
YES
Go to Step 5.
NO
Repair poor connection.

5. Communication circuit check between ICM and ECM

Check for open, short and high resistance in serial communication and clock circuit between ICM and ECM.

Is each communication circuit in good condition?
YES
Substitute a known-good ICM and recheck. If DTC P1621 is still detected, substitute a known good ECM and recheck.
NO
Repair circuit.