P1634

DTC P1634 (47): MPI Module Signal Circuit Problem
1. Reset the MCM.
2. Turn the ignition switch OFF.
3. Turn the ignition switch ON (II).
Is DTC P1634 indicated?
YES - Go to step 4.
NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the MPI module and at the MCM.
4. Turn the ignition switch OFF.
5. Turn the battery module switch OFF, and wait 5 minutes.
6. Remove the IPU lid, and make sure there is 30 V or less at the junction terminals.
7. Disconnect MCM connector A (31P).
8. Remove the PDU cover.
9. Disconnect the MPI module 16P connector.





10. Check for continuity between MCM connector terminal A18 and body ground.
Is there continuity?
YES - Repair short in the wire between the MPI module and the MCM (A18).
NO - Go to step 11.





11. Check for continuity between MCM connector terminal A18 and MPI module 16P connector terminal No. 3.
Is there continuity?
YES - Go to step 12.
NO - Repair open in the wire between the MPI module and the MCM (A18).





12. Check for continuity between MPI module 16P connector terminal No. 2 and No. 10 and body ground individually.
Is there continuity?
YES - Go to step 13.
NO - Repair open in the wire between the MPI module and G101.
13. Reconnect MCM connector A (31P).
14. Turn the ignition switch ON (II).





15. Measure voltage between MCM relay 2 4P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 16.
NO - Go to step 19.
16. Turn the ignition switch OFF.
17. Disconnect the negative cable from the 12 V battery.





18. Check for continuity between MCM relay 24P connector terminal No. 1 and MPI module 16P connector terminals No. 1 and No. 9 individually.
Is there continuity?
YES - Replace the MPI module.
NO - Repair open in the wire between the MPI module and the MCM relay 2.
19. Check MCM relay 2.
Is the relay OK ?
YES - Go to step 20.
NO - Replace the MCM relay 2.





20. Measure voltage between MCM relay 24P connector terminal No. 2 and body ground.
Is there battery voltage?
YES - Go to step 21.
NO - Repair open or short in the wire between the MCM relay 2 and No. 2 IMA (10A) fuse. Also replace the No. 2 IMA (10A) fuse.
21. Turn the ignition switch ON (II).





22. Measure voltage between MCM connector terminal A4 and body ground.
Is there battery voltage?
YES - Update the MCM if it does not have the latest software, or substitute a known-good MCM, then recheck. If the symptom/indication goes away with a known-good MCM, replace the original MCM.
NO - Repair open in the wire between the MCM relay 2 and the MCM (A4).