DTC Advanced Diagnostics: P0718
DTC P0718 : Mainshaft Speed Sensor Intermittent
General Description
The mainshaft speed sensor is built into the transmission. The mainshaft speed sensor generates different frequency pulse signal depending on the rotating speed of the gear on brake B1. The pulse signal is transmitted to the transmission control module (TCM) and used for measurement of the input shaft speed. When there is a missing pulse while the input shaft is rotating which occurs by open circuit, intermittent open circuit, and short circuit, the TCM detects as a malfunction. If the rotation speed measured by the mainshaft speed sensor fluctuates for a specified time within a specified period, the TCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | Within 2 seconds |
| DTC Type | Two drive cycles, MIL on, shift position indicator blinks |
Enable Conditions
| Condition | Minimum | Maximum | |
|---|---|---|---|
| Vehicle speed [Vehicle Speed] | 13 mph (21 km/h) | - | |
| Other | Not while shifting | ||
[ ]:HDS Parameter
Malfunction Threshold
The rotation speed measured by the mainshaft speed sensor fluctuates +/-470 rpm or more in 10 milliseconds, and the abnormal fluctuation occurs at least ten times within 2 seconds.
Possible Cause
- Mainshaft speed sensor intermittent failure
- Solenoid wire harness intermittent failure (includes a loose or disconnected connector)
- TCM internal circuit failure
Confirmation Procedure
Operating Condition
- Start the engine.
- Test-drive the vehicle from 1st gear to 10th gear at speeds over 13 mph (21 km/h).
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the TCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on, the shift position indicator blinks, and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool clear command.