FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0988

P0988






P0988-4C PRESSURE SWITCH RATIONALITY

Special Tools:










For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD, and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown.

- When Monitored:
Continuously with the ignition on, engine running, with the transmission in gear.

- Set Condition:
The DTC is set if the 4C Pressure Switch reads open or closed at the wrong time in a given gear.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.






1. CHECK FOR RELATED DTCs
1. With the scan tool, read DTCs.

Are there any TIPM TCM Power Control Circuit or TCM Power Input DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.

No

- Go To 2

2. DTC DATA SHOW CURRENT DTC
1. With the scan tool, check the Event Data.

NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

Does the Event Data show data for DTC P0988?

Yes

- Go To 3

No

- Testing and Inspection Perform the diagnostic procedure identified in the Event Data.

3. CHECK IF MULTIPLE DTCs ARE PRESENT

In the Event Data recorded earlier, are there two or more related Pressure Switch Sense DTCs present in addition to P0988?

Yes

- Go To 4

No

- Go To 7

4. RELATED DTC PRESENT

In the Event Data recorded earlier, do all the pressure switches read CLOSED for P0988?

Yes

- P0882 Perform the diagnostic procedure for the DTC P0882.

No

- Go To 5

5. CHECK IF THE PRESSURE SWITCHES READ OPEN

In the Event Data recorded earlier, do all the pressure switches read OPEN?

Yes

- Go To 6

No

- Go To 7

6. CHECK FOR LOW LINE PRESSURE

In the Event Data recorded earlier, is the Line Pressure less than 40 psi, and significantly below the Desired Line Pressure?

Yes

- Repair as necessary to correct low line pressure. Check fluid level and adjust as necessary. If fluid level is OK, check the Primary Oil Filter seal for a split, crack, or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump. Refer to the above procedures.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

7. CHECK IF THE DTC P0871 ALSO SET
1. With the scan tool, read DTCs.

Is the DTC P0871 also present?

Yes

- P0871 Perform the diagnostic procedure for P0871.

No

- Go To 8

8. CHECK IF THE DTC SET IN PARK, REVERSE OR NEUTRAL

In the Event Data recorded earlier, does the Event Data show the DTC P0988 set in Park, Neutral, or Reverse?

Yes

- Go To 13

No

- Go To 9

9. CHECK IF THE Event Data READS CLOSED

In the Event Data recorded earlier, does the Event Data show the 4C Pressure Switch reading CLOSED?

Yes

- Go To 11

No

- Go To 10

10. CHECK THE PRIMARY OIL FILTER SEAL

In the Event Data recorded earlier, is the Line Pressure less than 40 psi, and significantly below the Desired Line Pressure?

Yes

- Repair as necessary to correct low line pressure. Check fluid level and adjust as necessary. If fluid level is OK, check the Primary Oil Filter seal for a split, crack, or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump. Refer to the above procedures.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Go To 15

11. CHECK THE PCM AND WIRING USING THE TRANSMISSION SIMULATOR
1. Turn the ignition off to the lock position.
2. Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.

3. Install the Transmission Simulator.
4. Ignition on, engine not running.
5. With the Transmission Simulator, turn the Pressure Switch selector switch to the 4C position.
6. With the scan tool, monitor the 4C Pressure Switch while pressing the Pressure Switch test button on the Transmission Simulator.

Did the state of the 4C Pressure Switch change while pressing the Pressure Switch Test button?

Yes

- Go To 12

No

- Go To 13

12. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLY
1. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
2. Wiggle the wires while checking for shorted and open circuits.

Where there any problems found?

Yes

- Repair as necessary.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

13. CHECK THE (T48) 4C PRESSURE SWITCH SENSE CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the Transmission Simulator.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (T48) 4C Pressure Switch Sense circuit between the Transmission Solenoid/TRS Assembly harness connector and the appropriate terminal of the PCM C2 harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (T48) 4C Pressure Switch Sense circuit for an open.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Go To 14

14. CHECK THE (T48) 4C PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (T48) 4C Pressure Switch Sense circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (T48) 4C Pressure Switch Sense circuit for a short to ground.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Replace the Powertrain Control Module. With the scan tool, perform the Quick Learn procedure.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

15. CHECK IF THE NO. 5 AND/OR NO. 7 CHECK BALL IS CUT OR DAMAGED
1. Turn the Ignition off to the lock position.
2. Remove the Valve Body Assembly.
3. Inspect the No. 5 and No. 7 check balls for any cuts or damage.
4. Inspect the 4C accumulator piston and seals and also the 4C tower seal on top of the valve body. Refer to the Service Information.

Where there any problems found?

Yes

- Repair as necessary. Check for excessive clutch debris in the transmission oil pan. If excessive clutch debris is present, repair 4C clutch as necessary. Refer to the proper repair procedures.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Go To 16

16. CHECK FOR EXCESSIVE LEAKAGE WITHIN THE 4C CLUTCH CIRCUIT
1. Air check the 4C Clutch hydraulic circuit. Refer to the Service Information.

NOTE: This hydraulic clutch circuit contains a small bleed orifice. Small leakage is considered normal.

Was there excessive air leakage in the 4C Clutch hydraulic circuit?

Yes

- Repair as necessary. Refer to the Service Information.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

No

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Verification Test

pro multis Credits:Operation CHARM About Operation CHARM