1998 DTC P0717 Input Speed Sensor Circuit Low Input
The Automatic Transmission Input Speed Sensor (A/T ISS) is a permanent magnet with a coil of wire wound around it. The A/T ISS mounts in the transmission case facing the drive sprocket of the input shaft. As the drive sprocket is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.
An air gap of 0.08-2.12 mm (0.0032-0.0834 in) must be maintained between the sensor and the drive sprocket to insure proper operation of the A/T ISS. The A/T ISS is used by the PCM in order to control line pressure, TCC apply and release and transmission shift patterns. This sensor is also used to calculate the gear ratios and TCC slippage.
If the PCM detects a low input speed while the vehicle and engine speeds are high, then DTC P0717 sets. DTC P0717 is a Type B DTC.
Conditions for Setting the DTC
* No VSS DTCs P0502 or P0503 are set.
* No TFP Val. Position Sw. DTC P1810 is set.
* The engine speed is greater than 500 RPM for 5 seconds, and not in fuel shut off.
* The TFP Val. Position Sw. indicates that the transmission is not in Park or Neutral.
* The vehicle speed is greater than 8 km/h (5 mph).
* The input speed is less than 50 RPM for 5 seconds.
Action Taken When the DTC Sets
* The PCM illuminates the Malfunction Indicator Lamp (MIL).
* The PCM disables shift adapts.
Conditions for Clearing the MIL/DTC
* The PCM turns OFF the MIL after three consecutive trips without a failure reported.
* A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
* The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.
* Check for Electromagnetic Interference (EMI) in circuits 1230 and 1231. EMI may be induced if the harness is routed along the spark plug wires. Inspect the wiring at the PCM, transmission 20-way connector, ISS 2-way connector and all other circuit connecting points for the following conditions:
o A bent terminal
o A backed out terminal
o A damaged terminal
o Poor terminal tension
o A chafed wire
o A broken wire inside the insulation
o Moisture Intrusion
* When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
* Inspect the transmission 20-way connector for transmission fluid.
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that the PCM receives a signal from the A/T ISS Sensor.
This step verifies that there are no opens in the circuitry from the A/T ISS to the PCM.
This step verifies that there are no opens in the circuitry from the A/T ISS to the transmission 20-way connector.
This step performs a resistance check on the A/T ISS and the automatic transmission wiring harness.
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