P0720

DTC P0720: Problem in Countershaft Speed Sensor Circuit

NOTE: Record all freeze data and review General Troubleshooting Information before you troubleshoot.

1. Check the countershaft speed sensor installation.
Is the countershaft speed sensor installed properly ?
YES-Go to step 2.
NO-Reinstall and recheck.
2. Disconnect countershaft speed sensor connector (2P).





3. Measure countershaft speed sensor resistance at the sensor connector.
Is there 400 - 600 Ohms ?
YES-Go to step 4.
NO-Replace the countershaft speed sensor.
4. Disconnect PCM connector C (22P).





5. Check for continuity between PCM connector terminal C14 and body ground, and between terminal C15 and body ground.
Is there continuity?
YES-Repair short to ground in the wires between PCM connector terminals C14 and C15, and the countershaft speed sensor.
NO-Go to step 6.
6. Connect countershaft speed sensor connector.





7. Measure the resistance between PCM connector terminals C14 and C15.
Is there 400 - 600 Ohms ?
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.
NO-Repair loose terminal or open in the wires between PCM connector terminals C14 and C15, and the countershaft speed sensor.