Diagnostic Instructions
DTC Descriptors
DTC P1684: Transmission Control Module (TCM) Power Up Temperature Sensor Performance
DTC P1685: Transmission Control Module (TCM) Power Up Temperature Sensor Circuit Low Voltage
DTC P1686: Transmission Control Module (TCM) Power Up Temperature Sensor Circuit High Voltage
Circuit/System Description
The transmission control module (TCM) power up temperature sensor is located inside of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The TCM power up temperature sensor provides the temperature of the TCM at
TCM power up. This temperature reading is used in various shifting and diagnostic routines in the TCM software. This fault is handled inside the TCM and no external circuits are involved.
Conditions for Running the DTC
The engine speed is greater than 450 RPM.
P1684
For conditions 1 and 2:
| • | No DTCs P0711, P0712, P0713, P0716, P0717, P0722, P0723, or P1684. |
| • | Start the ignition voltage, run the engine. |
| • | DTC P1684 failed this ignition cycle. |
| • | TCM power up temperature is between -39 and +149°C (-38 and +300°F). |
For conditions 3:
Start the ignition voltage, run the engine.
P1685
| • | Start the ignition voltage, run the engine. |
| • | DTC P0716, P0717, P0722, P0723 or P1686 are not set. |
| • | The transmission output shaft speed is greater than 200 RPM for greater than 200 seconds. |
| • | The torque converter clutch (TCC) slip speed is equal to or greater than 120 RPM for 200 seconds or greater. |
P1686
| • | Start the ignition voltage, run the engine. |
| • | DTC P1686 passed this ignition cycle. |
Conditions for Setting the DTC
P1684
Fail Case 1
| • | Vehicle speed is greater than 8 km/h (5 mph) for 300 seconds cumulative. |
| • | TCC slip speed is greater than 120 RPM for 300 seconds cumulative. |
| • | The TCM power up temperature is between -40 and +21°C (-40 and +70°F). |
| • | The TCM power up temperature has changed by less than 2°C (3.6°F) in 100 seconds. |
| • | The transmission fluid temperature (TFT) is greater than 70°C (158°F). |
| • | The TFT has increased by 55°C (99°F) since startup. |
Fail Case 2
| • | Vehicle speed is greater than 8 km/h (5 mph) for 300 seconds cumulative. |
| • | TCC slip speed is greater than 120 RPM for 300 seconds cumulative. |
| • | The TCM temperature sensor is between 120-150°C (248-302°F). |
| • | The TCM power up temperature has changed by less than 2°C (3.6°F) in 100 seconds. |
| • | The TFT is greater than 70°C (158°F). |
| • | The TFT has increased by 55°C (99°F) since startup. |
Fail Case 3
The TCM power up temperature changes by greater than or equal to 20°C (36°F) 14 times over 7 seconds.
P1685
The TCM power up temperature is less than or equal to -61°C (-77°F) for greater than 10 seconds.
P1686
The TCM power up temperature is greater than or equal to 161°C (321°F) for greater than 10 seconds.
Action Taken When the DTC Sets
| • | DTCs P1684, P1685, and P1686 are Type C DTCs. |
| • | The TCM allows the vehicle to operate in transmission protection mode. |
Conditions for Clearing the DTC
DTCs P1684, P1685, and P1686 are Type C DTCs.
Diagnostic Aids
Reprogram the TCM and retest the DTC to see if the DTC resets.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
DTC Type Reference
Electrical Information Reference
Circuit/System Testing
- Clear the DTC and operate the vehicle under the Conditions for Running the DTC and the Conditions for Setting the DTC.
- Shut the ignition OFF for 30 seconds, and then verify that the DTC does not reset.
| ⇒ | If the DTC resets, replace the control solenoid (w/body and TCM) valve assembly. |
Component Testing
Perform the
Control Solenoid Valve and Transmission Control Module Assembly Inspection.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
