P0641-SENSOR REFERENCE VOLTAGE 1 CIRCUIT
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
A common 5-volt power supply is used by both the primary and secondary pressure sensors as well as an internal ROM Assembly. If the power supply does not maintain a predetermined voltage range to the pressure sensors after the period of 5.0 seconds, the Transmission Control Module (TCM) sets the DTC and illuminates the MIL.
- When Monitored:
Ignition on with system voltage between 9.0 and 16.0 volts.
- Set Condition:
When the monitored input voltage from primary pressure sensor and secondary pressure sensor is less than 0.05 volts for a continuous period of 5.0 seconds.
| Possible Causes |
| (T72) 5-VOLT SUPPLY CIRCUIT OPEN |
| (T72) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND |
| INTERNAL TRANSMISSION |
| TRANSMISSION CONTROL MODULE |
Always perform the CVT Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
Diagnostic Test
1. CHECK TO SEE IF THE DTC IS ACTIVEWith the scan tool, read Transmission DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter 2 or less?
Yes
- Go To 2
No
- Go To 5
2. CHECK THE (T72) 5-VOLT SUPPLY CIRCUIT VOLTAGE
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Ignition on, engine not running.
Measure the voltage of the (T72) 5-volt Supply circuit.
Is the voltage 5.0 volts (± 0.5 volts)?
Yes
- Replace the CV Transmission or the Valve Body per the Service Information.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 3
3. CHECK THE (T72) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Measure the resistance of the (T72) 5-volt Supply circuit between the TCM C2 harness connector and the Transmission Solenoid/Pressure Switch Assembly harness connector.
Is the resistance above 5.0 ohms?
Yes
- Repair the (T72) 5-volt Supply circuit for an open.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 4
4. CHECK THE (T72) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (T72) 5-volt Supply circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (T72) 5-volt Supply circuit for a short to ground.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for any Service Bulletins for possible causes that may apply. If no problems are found, replace the TCM per the Service Information.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
5. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorted and open circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Test Complete.