Circuit Description
The automatic transmission input shaft speed sensor (AT ISS) is a permanent magnet generator. The AT ISS mounts in the transmission case facing the drive sprocket of the input shaft. As the drive sprocket rotates, an AC voltage is induced and transmitted to the PCM. The PCM converts the AC voltage into a digital signal. The PCM uses the input shaft speed signal to determine shift timing, torque converter clutch slip speed and gear ratio.
If the PCM detects an unrealistic change in RPM from the AT ISS, then DTC P0716 sets. DTC P0716 is a type B DTC.
Conditions for Running the DTC
| • | No TP DTCs P0121, P0122 or P0123. |
| • | No VSS DTCs P0502 or P0503. |
| • | No AT ISS DTC P0717. |
| • | No 1-2 shift solenoid valve performance DTCs P0751 or P0752. |
| • | No 1-2 shift solenoid valve electrical DTCs P1842 or P1843. |
| • | The engine run time is greater than 5 seconds. |
| • | The internal mode switch indicates D4. |
| • | The TP angle is 12 percent or greater. |
| • | The vehicle speed is 16 km/h (10 mph) or greater. |
| • | The transmission input shaft speed is greater than 1,050 RPM for at least 2 seconds. |
| • | The transmission input shaft speed has not increased by 500 RPM or greater for at least 2 seconds. |
Conditions for Setting the DTC
The transmission input shaft speed drops by 1,000 RPM or greater for at least 1 second.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM calculates input shaft speed from vehicle speed and commanded gear. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The PCM stores DTC P0716 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | 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. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the AT ISS for correct resistance.
-
Replace the PCM only after completing all circuit tests.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.0L | ||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Is the transmission input speed greater than the specified value? | 500 RPM | Go to Intermittent Conditions in Engine Controls - 4.0L | Go to Step 3 | ||||
Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance within the specified range? | 1,300-1,950 ohms | Go to Step 6 | Go to Step 4 | |||||
4 | Test the high signal circuit (CKT 1230) of the AT ISS for an open or short to ground between the AT inline 20-way connector and the AT ISS. Refer to Circuit Testing in Wiring Systems. Did you find the condition? | -- | Go to Step 8 | Go to Step 5 | ||||
5 | Test the low signal circuit (CKT 1231) of the AT ISS for an open between the AT inline 20-way connector and the AT ISS. Refer to Testing for Continuity in Wiring Systems. Did you find the condition? | -- | Go to Step 8 | Go to Step 9 | ||||
6 | Test the high signal circuit (CKT 1230) of the AT ISS for an open or short to ground between the PCM connector C1 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition. | -- | Go to Step 11 | Go to Step 7 | ||||
7 | Test the low signal circuit (CKT 1231) of the AT ISS for an open between the PCM connector C1 and the AT inline 20-way connector. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 | ||||
8 |
Important: The automatic transmission wiring harness consists of two separate harnesses, the Automatic Transmission Wiring Harness Assembly, GM P/N 15320475, and the Automatic Transmission Wiring Extension Harness Assembly, GM P/N 15320478. In order to avoid the unnecessary replacement of parts, only replace the Automatic Transmission Wiring Harness Assembly, GM P/N 15320475. Replace the automatic transmission wiring harness. Refer to Input Speed Sensor and Wiring Harness Removal in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
9 | Replace the AT ISS. Refer to Input Speed Sensor and Wiring Harness Removal in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.0L. Did you complete the replacement? | -- | Go to Step 11 | -- | |||||
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 | ||||
12 | 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? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.0L | System OK |
