Circuit Description
The automatic transmission input shaft speed (AT ISS) sensor provides transmission input speed to the powertrain control module (PCM). The AT ISS sensor is a permanent magnet generator. The sensor mounts into the transmission case and maintains a slight air gap between the sensor and the forward clutch housing. The PM generator produces an AC voltage as the forward clutch housing rotor teeth pass through the sensor's magnetic field. The AC voltage level increases as the turbine shaft speed increases. The PCM converts the AC voltage into a digital signal. The PCM determines actual turbine speed using the digital signal. The PCM uses the input speed to calculate torque converter slip speed, and gear ratios.
When the PCM detects a low or no input speed during high vehicle and high engine speeds, DTC P0717 sets. DTC P0717 is a type C DTC. For California emissions vehicles, DTC P0717 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0717 Input Speed Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | No AT VSS DTC P0502 or P0503. |
| • | No TFP manual valve position switch DTC P1810. |
| • | The system voltage is 8-18 volts for greater than 0.5 second. |
| • | TFP manual valve position switch is not indicating PARK or NEUTRAL. |
| • | The vehicle speed is greater than 26 km/h (16 mph). |
| • | The engine is running for greater than 7 seconds. |
Conditions for Setting the DTC
The measured input speed is less than 80 RPM for at least 5 seconds.
Action Taken When the DTC Sets
| • | For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated. |
| • | The PCM defaults the transmission to maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal. |
| • | The PCM stores the DTC P0717 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring. |
| • | For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
DTC P0717 defaults to an elevated line pressure condition which may result in partial torque converter clutch (TCC) apply. This may produce an idle surge that could stall the engine.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for proper circuit operation up to the PCM connections.
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This step tests for proper operation of the AT ISS sensor.
Step | Action | Value | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info Function will erase the data. With the drive wheels rotating, does the scan tool Transmission ISS increase with the drive wheel speed? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||
Does the resistance measure within the specified range? | 1,420-2,140 ohms | Go to Step 4 | Go to Step 6 | |||||
4 | Measure the resistance from the ISS high signal circuit to ground. Does the resistance measure greater than the specified value? | 10 M ohms | Go to Step 5 | Go to Step 8 | ||||
5 |
Refer to Testing for a Short to Voltage and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
Does the resistance measure within the specified range? | 1,420-2,140 ohms | Go to Step 7 | Go to Step 11 | |||||
7 | Was the resistance measured in Step 3 greater than the specified value? | 2,140 ohms | Go to Step 9 | Go to Step 10 | ||||
8 |
Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | -- | ||||
9 |
Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | -- | ||||
10 | Test the AT ISS high circuit and the AT ISS low circuit for a short together. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | -- | ||||
11 | Replace the ISS assembly. Refer to Input Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
12 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
13 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 14 | Go to Step 2 | ||||
14 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
