P1901
DTC P1901: Open in Auxiliary Transmission Fluid Pump (ATFP) Relay Circuit or ATFP Relay Stuck OFFNOTE:
^ Record all freeze data and review General Troubleshooting Information before you troubleshoot.
^ This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.
1. Clear the DTC with the HDS.
2. Turn the ignition switch ON (II), wait for more than 10 seconds, then check that DTC P1901 recurs.
Is DTC P1901 indicated?
YES - Go to step 3.
NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ATFP control unit, the PCM, and the ATFP relay.
3. Turn the ignition switch OFF.
4. Check for a blown No. 37 (30 A) fuse in the auxiliary under-hood fuse/relay box B.
Is the fuse OK?
YES - Go to step 5.
NO - Replace the No. 37 (30 A) fuse in the auxiliary under-hood fuse/relay box B, and check for a short in the wire between the positive battery terminal and the auxiliary under-hood fuse/relay box B, and between the auxiliary under-hood fuse/relay box B and the ATFP control unit, then go to step 13.
5. Remove the ATFP relay from the auxiliary underhood fuse/relay box B, and check for continuity between relay terminals,
Is the relay OK?
YES - Go to step 6.
NO - Replace the ATFP relay, then go to step 13.
6. Turn the ignition switch ON (II).
7. Measure the voltage between ATFP relay socket terminal No. 1 and body ground, and between terminal No. 4 and body ground.
Is there battery voltage?
YES - Go to step S.
NO - Replace the auxiliary under-hood fuse/relay box B and the wire harness between the battery and the fuse/relay box, then go to step 13.
8. Turn the ignition switch OFF.
9. Disconnect the ATFP control unit connector.
10. Check for continuity between ATFP control unit connector terminal No. 3 and ATFP relay socket terminal No. 2.
Is there continuity?
YES - Go to step 11.
NO - Repair an open in the wire between ATFP control unit terminal No. 3 and the auxiliary underhood fuse/relay box B, then go to step 13.
11. Install the ATFP relay in the auxiliary under-hood fuse/relay box B.
12. Measure the voltage between ATFP control unit connector terminal No. 8 and body ground.
Is there battery voltage?
YES - Replace the ATFP control unit, then go to step 13.
NO - Repair an open in the wire between ATFP control unit connector terminal No. 8 and the auxiliary under-hood fuse/relay box B, then go to step 13.
13. Clear the DTC with the HDS.
14. Turn the ignition switch ON (II), and wait for more than 10 seconds.
15. Monitor the OBD status for P1901 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the result indicate PASSED?
YES - Troubleshooting is complete.
NO - Return to step 3 and recheck.