DTC Troubleshooting: P0718 (15-6)

DTC P0718:

Input Shaft (Mainshaft) Speed Sensor Intermittent Failure

• Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information.
• 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.	Test-drive the vehicle for several minutes in the D position through all five gears.

3.

Monitor the OBD status for P0718 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail. Does the result indicate FAILED? YES - Go to 4. NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the input shaft (mainshaft) speed sensor and the PCM. If the tester indicates NOT COMPLETED, return to 2 and recheck.n

4.	Turn the ignition switch OFF.

5.	Disconnect the input shaft (mainshaft) speed sensor connector, and inspect the connector and connector terminals to be sure they are making good contact. Are the connector terminals OK? YES - Go to 6. NO - Repair the connector terminals, then go to 6.

6.	Connect the input shaft (mainshaft) speed sensor connector.

7.	Test-drive the vehicle for several minutes in the D position through all five gears.

8.	Monitor the OBD status for P0718 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail. Does the result indicate FAILED? YES - Go to 9. NO - Troubleshooting is complete. If the tester indicates NOT COMPLETED, return to 7 and recheck.n

9.	Turn the ignition switch OFF.

10.	Jump the SCS line with the HDS.

11.	Disconnect PCM connector C (44P).

12.	Check for continuity between PCM connector terminals C40 and body ground, and between C44 and body ground.   Is there continuity? YES - Go to 13. NO - Repair open in the wires between PCM connector terminals C40, C44, and ground (G101), or repair poor ground (G101), then go to 30.

13.	Connect PCM connector C (44P).

14.	Disconnect the input shaft (mainshaft) speed sensor connector.

15.	Turn the ignition switch ON (II).

16.	Measure voltage between input shaft (mainshaft) speed sensor connector terminal No. 1 and body ground.   Is there about 5 V? YES - Go to 17. NO - Go to 26.

17.	Turn the ignition switch OFF.

18.	Disconnect PCM connector B (44P).

19.	Check for continuity between input shaft (mainshaft) speed sensor connector terminal No. 2 and body ground.   Is there continuity? YES - Repair short to ground in the wire between PCM connector terminal B17 and the input shaft (mainshaft) speed sensor connector, then go to 30. NO - Go to 20.

20.	Connect PCM connector B (44P).

21.	Turn the ignition switch ON (II).

22.	Measure voltage between input shaft (mainshaft) speed sensor connector terminal No. 2 and body ground.   Is there about 5 V? YES - Replace the input shaft (mainshaft) speed sensor, then go to 30. NO - Go to 23.

23.	Turn the ignition switch OFF.

24.	Disconnect PCM connector B (44P).

25.

Check for continuity between PCM connector terminal B17 and input shaft (mainshaft) speed sensor connector terminal No. 2.   Is there continuity? YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original  PCM.n NO - Repair open in the wire between PCM connector terminal B17 and the input shaft (mainshaft) speed sensor, then go to 30.

26.	Turn the ignition switch OFF.

27.	Disconnect PCM connector B (44P).

28.	Check for continuity between PCM connector terminal B18 and input shaft (mainshaft) speed sensor connector terminal No. 1.   Is there continuity? YES - Go to 29. NO - Repair open in the wire between PCM connector terminal B18 and the input shaft (mainshaft) speed sensor, then go to 30.

29.

Check for continuity between PCM connector terminal B18 and body ground.   Is there continuity? YES - Repair short to ground in the wire between PCM connector terminal B18 and the input shaft (mainshaft) speed sensor, then go to 30. NO - Check for loose or poor connections at PCM connector terminal B18. If the connection is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original  PCM.n

30.	Clear the DTC with the HDS.

31.	Test-drive the vehicle for several minutes in the D position through all five gears.

32.	Monitor the OBD status for P0718 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail. Does the result indicate PASSED? YES - Troubleshooting is complete.n NO - Return to 1 and recheck.