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 500 RPM or greater for 5 seconds. |
| • | The ignition voltage is between 8.6 volts and 19.0 volts. |
P1684
| • | No TFT DTCs P0711, P0712, or P0713. |
| • | No ISS DTCs P0716 or P0717. |
| • | No OSS DTCs P0722 or P0723. |
| • | DTC P1684 has not passed this key ON. |
| • | The TCM power up temperature is between -39 and +149°C (-38 and +300°F) for Fail Case 1 and 2. |
P1685
| • | No ISS DTCs P0716 or P0717. |
| • | No OSS DTCs P0722 or P0723. |
| • | The transmission output shaft speed is 200 RPM or greater for 200 seconds or more. |
| • | The torque converter clutch (TCC) slip speed is 120 RPM or greater for 200 seconds or more. |
| • | DTC P1686 has not failed this ignition cycle. |
P1686
DTC P1686 has not failed this ignition cycle.
Conditions for Setting the DTC
P1684 - Fail Case 1
| • | Vehicle speed is 8 km/h (5 mph) or greater 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 70°C (158°F) or greater. |
| • | The TFT has increased by 55°C (99°F) since startup. |
P1684 - Fail Case 2
| • | Vehicle speed is 8 km/h (5 mph) or greater 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 70°C (158°F) or greater. |
| • | The TFT has increased by 55°C (99°F) since startup. |
P1684 - Fail Case 3
The TCM power up temperature changes by 20°C (36°F) or greater 14 times over 7 seconds.
P1685
The TCM power up temperature is -59°C (-74°F) or less for 10 seconds or greater.
P1686
The TCM power up temperature is 164°C (327°F) or more for 10 seconds or greater.
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.
- Control solenoid (w/body and TCM) valve assembly replacement - refer to
Control Module References
for replacement, setup, and programming.
- Perform the
Service Fast Learn Adapts
.
