P1638

DTC P1638: Immobilizer Information Mismatched

Immobilizer Control System Wiring Circuit Diagram

DTC Detecting Condition and Trouble Area






Troubleshooting

1. Diagnostic Trouble Code (DTC) confirmation

Clear DTC(s) referring to DTC Clearance DTC Clearance.
Turn the ignition switch to OFF position.
Check if any DTC is detected referring to DTC Check DTC Check.

Is DTC P1638 still detected?
YES -
Go to Step 2.
NO -
The troubleshooting is completed.

2. Diagnostic Trouble Code (DTC) confirmation

Disconnect negative (-) cable from battery for more than 5 seconds.
Connect negative (-) cable to battery.
Check if any DTC is detected referring to DTC Check DTC Check.

Is DTC P1638 still detected?
YES -
Go to Step 3.
NO -
The troubleshooting is completed.

3. Check ECM specification

Check ECM part number to see if ECM is applicable to the vehicle in service.

Is a correct ECM used for the vehicle in service?
YES -
Go to Step 4.
NO -
Replace ECM with the correct one and recheck if DTC P1638 is still detected by ECM.

4. Diagnostic Trouble Code (DTC) check in ECM

Is any DTC other than P1638 detected in Step 1?
YES -
Perform the troubleshooting referring to the corresponding flowchart.
NO -
Go to Step 5.

5. Diagnostic Trouble Code (DTC) check in BCM

Check BCM for DTC referring to DTC Check DTC Check.

Is any DTC detected?
YES -
Perform the troubleshooting referring to the corresponding flowchart in Section 10B.
NO -
Go to Step 6.

6. Replacement of BCM

Replace BCM with new one referring to Service and Repair BCM Removal and Installation.
Check ECM for DTC referring to DTC Check DTC Check.

Is DTC P1638 still detected?
YES -
Go to Step 7.
NO -
The troubleshooting is completed.

7. Replacement of ECM

Replace ECM with new one referring to ECM (Engine Control Module) Removal and Installation ECM (Engine Control Module) Removal and Installation.
Check ECM for DTC referring to DTC Check DTC Check.

Is DTC P1638 still detected?
YES -
Recheck CAN communication wire circuits and poor connection at ECM, ABS control module and BCM connectors.
NO -
The troubleshooting is completed.