P0842-PRIMARY OIL PRESSURE SENSOR CIRCUIT LOW
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
The Transmission Control Module (TCM) monitors the input voltage from the primary pulley pressure sensor. When the voltage is below a predetermined limit a DTC will set.
- When Monitored:
Ignition on, system voltage between 9.0 and 16.0 volts.
Transmission temperature greater than -20° C (-4° F)
No active DTCs from the following:
- Primary Oil Pressure Sensor High
- Sensor ground
- Set Condition:
When the monitored voltage drops below 0.09 volts for the period of 5 seconds.
| Possible Causes |
| (T72) 5 VOLT SUPPLY CIRCUIT OPEN |
| (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT OPEN |
| (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO GROUND |
| PRIMARY PRESSURE SENSOR |
| 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 THE PRIMARY PRESSURE SENSOR VOLTAGEWith the scan tool, read the Primary Pulley Pressure Sensor voltage.
Is the voltage below 0.09 volts?
Yes
- Go To 2
No
- Go To 7
2. CHECK THE (T72) 5 VOLT SUPPLY CIRCUIT
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 in the Transmission Solenoid/Pressure Switch Assembly harness connector.
Is the voltage 5.0 volts (± 0.2 volts)?
Yes
- Go To 3
No
- Go To 6
3. CHECK THE (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Ignition on, engine not running.
Connect a jumper wire between the (T21) Primary Pressure Sensor Signal circuit and the (T72) 5 Volt Supply circuit in the Transmission Solenoid/Pressure Switch Assembly harness connector.
With the scan tool, read the Primary Pulley Pressure Sensor voltage.
Is the voltage 5.0 volts (± 0.2 volts)?
Yes
- Replace CV Transmission or replace the Primary Pressure Sensor (Valve Body) per the Service Information.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 4
4. CHECK THE (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Measure the resistance of the (T21) Primary Pressure Sensor Signal 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 (T21) Primary Pressure Sensor Signal circuit for an open or high resistance.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 5
5. CHECK THE (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (T21) Primary Pressure Sensor Signal circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (T21) Primary Pressure Sensor Signal 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)
6. CHECK THE (T72) 5 VOLT SUPPLY CIRCUIT FOR AN OPEN
While back probing, measure the voltage of the (T72) 5 Volt Supply circuit in Transmission Solenoid/Pressure Switch Assembly harness connector.
Is the voltage 5.0 volts (± 0.2 volts)?
Yes
- Repair the (T72) 5 Volt Supply circuit for an open or high resistance.
- 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)
7. 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.