Circuit Description
The Input Shaft Speed (ISS) sensor is mounted on the top of transaxle. As the transaxle turns the ISS detects the rotation speed of the input turbine. The signal is input from the sensor to the PCM. The signal controls the engine torque, shift timing and torque converter clutch operation.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | The vehicle speed is 50 km (20 mph) or greater. |
| • | The transmission is in 2nd, 3rd or O/D. |
| • | Shift solenoids and PNP switch are operating correctly. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer. |
Conditions for Clearing the MIL/DTC
| • | The MIL turns OFF after 3 consecutively passing trips without a fault present. |
| • | A History DTC clears after 40 consecutive warm-up cycles without a fault. |
| • | Use the scan tool Clear DTC Information function. |
Diagnostic Aids
A scan tool should indicate a input shaft speed whenever the drive wheels are turning at a speed of more than 5 km/h (3 mph). DTC P1725 can be falsely set if the engine is brake-torqued in gear. Disregard DTC P1725 if the DTC sets when the drive wheels are not turning.
An intermittent malfunction may be caused by a fault in the ISS sensor electrical circuit. Inspect the wiring harness and the components for any of the following conditions:
| • | Any backed-out terminals |
| • | Any improper mating of terminals |
| • | Any broken electrical connector locks |
| • | Any improperly formed or damaged terminals |
| • | Any faulty terminal-to-wire connections |
| • | Any physical damage to the wiring harness |
| • | A broken wire inside the insulation |
| • | Any corrosion of the electrical connections, the splices, or the terminals |
Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.
The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
-
This step checks the ISS for an output signal.
-
This step checks the ISS sensor resistance.
-
This step checks the wiring from the sensor to the PCM connector.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
Does the scan tool parameter indicate a vehicle speed? | -- | Go to Step 3 | Go to Step 4 | |
3 |
Does DTC P1725 set? | -- | Go to Step 4 | Go to Diagnostic Aids |
Is the resistance within the specified value? | 560 - 680 ohms at 20°C (68°F) | Go to Step 5 | Go to Step 7 | |
Is the resistance within the specified value? | 560 - 680 ohms at 20°C (68°F) | Go to Step 8 | Go to Step 6 | |
6 | Repair the open or short to ground. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 9 | -- |
7 | Replace the Input Shaft Speed (ISS) sensor. Is the replacement complete? | -- | Go to Step 9 | -- |
8 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the replacement complete? | -- | Go to Step 9 | -- |
9 |
Are any DTCs displayed on the scan tool? | -- | System OK | |
