P0843-PRIMARY OIL PRESSURE SENSOR CIRCUIT HIGH

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 above 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 Low
Sensor ground
Set Condition:
When the monitored voltage rises above 4.7 volts for the period of 5 seconds.

Possible Causes

(T72) 5 VOLT SUPPLY CIRCUIT SHORT TO VOLTAGE

(T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE

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 VOLTAGE

With the scan tool, read the Primary Pulley Pressure Sensor voltage.

Is the voltage greater than 4.7 volts?

Yes

Go To 2

Go To 6

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 between 4.5 and 5.5 volts?

Yes

Go To 3

Go To 5

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.
With the scan tool, read the Primary Pulley Pressure Sensor voltage.

Does the scan tool read any voltage?

Yes

Go To 4

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)

4. CHECK THE (T21) PRIMARY PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Ignition on, engine not running.
Measure the voltage of the (T21) Primary Pressure Sensor Signal circuit.

Is there any voltage present?

Yes

Repair the (T21) Primary Pressure Sensor Signal circuit for a short to voltage.

Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

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. CHECK THE (T72) 5 VOLT SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE

Turn the ignition off to the lock position.
Disconnect the TCM C2 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 there any voltage present?

Yes

Repair the (T72) 5 Volt Supply circuit for a short to voltage.

Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

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. 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)

Test Complete.