68RFE Automatic Transmission

P2704-INADEQUATE ELEMENT VOLUME 4C

For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


Theory of Operation


The volumes of the transmission fluid needed to apply the friction elements are continuously monitored and learned for adaptive controls. As the clutch friction material wears, the volume of fluid needed to apply the clutch increases. Certain transmission mechanical problems can cause near-zero learned volumes resulting in setting a DTC. The DTC will usually set with other DTCs, which indicates an internal transmission problem.


- When Monitored:

Whenever the engine is running. The 4C clutch volume index (CVI) is updated during a 4-5 upshift with throttle angle between 10 and 54 degrees. Transmission temperature must be at least 43� C (110� F).

- Set Condition:

When the 4C CVI falls below 5.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 68RFE Pre-Diagnostic Troubleshooting Procedure



Diagnostic Test


1. CHECK THE 4C CLUTCH VOLUME

With the scan tool, record the 4C clutch volume index (CVI) and erase DTCs.

Perform at least 10, 4-5 upshifts with the throttle between 10 and 54 degrees. The Transmission temperature must be at least 43� C or 110� F.

With the scan tool, read the 4C CVI.

Is the current 4C CVI below 10?

Yes

- Go To 2

No

- Go To 5



2. DTC P0876 PRESENT

With the scan tool, read DTCs.


NOTE: The DTC P0876 must also be set with P2704 in order for this test to be valid.

Is the DTC P0876 also present?

Yes

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

No

- Go To 3



3. 4C CLUTCH CIRCUIT LEAKS IN THE VALVE BODY

Turn the ignition off to the lock position.

Remove the transmission oil pan.

Remove the valve body.

Check condition of the 4C accumulator springs.

Look for possible leak paths into the 4C clutch hydraulics circuit within the valve body.

Were any problems found?

Yes

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

No

- Go To 4



4. AIR CHECK 4C CLUTCH CIRCUIT

Perform an air check on the 4C Clutch circuit.

Listen for proper 4C Clutch piston movement.

Were any problems found?

Yes

- Repair Internal transmission as necessary. Pay attention to the mechanical components related to the 4th clutch. A broken or weak return spring or a dislocated snap ring could cause this problem.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Replace the Transmission Solenoid/TRS Assembly. With the scan tool, perform Quick Learn.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test



5. VERIFY PCM OPERATION

Perform eight learnable starts. A learnable start is defined as follows: Start engine. From a standstill, accelerate lightly to 50 MPH, then brake lightly to a stop. Turn off engine.

With the scan tool, record Transmission CL VOL INDEX (CVI) for all clutches.

With the scan tool, perform a BATTERY DISCONNECT.

With the scan tool, read the CVIs and compare them to the reading recorded before the BATTERY DISCONNECT.

Are any of the CVIs less than 5 or are they different than before the battery disconnect?

Yes

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM. With the scan tool, perform QUICK LEARN.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Test Complete.