P1644

DTC P1644: MOTFSA Motor Control Module Signal Malfunction

NOTE: Inform marked with an asterisk (*1) applies to DTC P1645, an asterisk (*2) applies to DTC P1646.

1. Reset the ECM.
2. Turn the ignition switch ON (II).

Is DTC P1644, P1645 or P1646 indicated?

YES - Go to step 3.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the motor control module and at the ECM.

3. Turn the ignition switch OFF.
4. Remove the IPU cover, and disconnect the motor control module connector A (32P).
5. Turn the ignition switch ON (II).




6. Measure voltage between ECM connector terminal D2, (D1)*1, (D3)*2 and body ground.

Is there about 5 V?

YES - Go to step 10.

NO - Go to step 7.

7. Turn the ignition switch OFF.
8. Disconnect ECM connector D (16P).




9. Check for continuity between ECM connector terminal D2, (D1)*1, (D3)*2 and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM (D2, (D1)*1, (D3)*2) and the motor control module.

NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.

10. Turn the ignition switch OFF.
11. Disconnect ECM connector D (16P).




12. Check for continuity between ECM connector terminal D2, (D1)*1, (D3)*2 and motor control module connector terminal A16, (A15)*1, (A4)*2.

Is there continuity?

YES - Replace the motor control module.

NO - Repair open in the wire between the ECM D2, (D1)*1 (D3)*2 and the motor control module.