P1770

P1770-INADEQUATE ELEMENT VOLUME LR

For a complete wiring diagram Consult Diagrams/Electrical.

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 DTC's, which indicates an internal transmission problem.

- When Monitored:
Whenever the engine is running. The LR Clutch Volume Index (CVI) is updated during a 3-1 or 2-1 manual downshift with throttle angle below 5 degrees. Transmission temperature must be at least 43° C (110° F).

- Set Condition:
When the LR Clutch Volume Index (CVI) falls below a calibrated value.





Always perform the 62TE Pre-Diagnostic Troubleshooting procedure before proceeding.Testing and Inspection

Diagnostic Test

1. OTHER DTCS PRESENT
With the scan tool, check DTCs.
Are there any Pressure Switch Sense circuit DTCs present also?

Yes

- Diagnose and repair the DTC(s).

No

- Go to 2

2. CHECK L/R CLUTCH VOLUME INDEX
With the scan tool, erase DTCs.
Start the engine and warm the transmission.

NOTE: The TRANS TEMP DEG must be at least 43° C or (110° F) before performing the following steps.

Drive the vehicle and perform at least ten 3-1 manual downshifts at closed throttle from speeds of about 32 Kmh or 20 MPH.
With the scan tool, read the L/R CL VOL INDEX.
Is the LR CL VOL INDEX below 20?

Yes

- Go to 3

No

- Go to 5

3. L/R 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 L/R accumulator springs.
Look for possible leak paths into the L/R clutch hydraulics circuit within the valve body.
Were any problems found?

Yes

- Repair as necessary.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Go to 4

4. AIR CHECK L/R CLUTCH CIRCUITS
Perform an air check on the L/R Clutch circuit.
Watch and listen for L/R Clutch piston movement.
Does the L/R piston stroke and return properly?

Yes

- Replace the Transmission/TRS Solenoid Assembly. With the scan tool, perform Quick Learn.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Repair internal transmission as necessary. Pay attention to the components related to the L/R clutch. A broken or weak L/R clutch return spring, Accumulator Spring, and/or dislocated snap ring could cause this problem.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

5. VERIFY PCM OPERATION

NOTE: The TRANS TEMP DEG must be at least 43° C or 110° F before performing the following steps.

Perform eight learnable starts. A learnable start is defined as follows: Start engine. From a standstill, accelerate lightly to 80 Kmh or 50 MPH, then brake lightly to a stop. Turn off engine.
With the scan tool, record the CL VOL INDEX (CVI) for all clutches
With the scan tool, perform a BATTERY DISCONNECT.
With the scan tool, read the CVI's and compare them to the readings recorded before the BATTERY DISCONNECT.
Are any of the CVI's less than 5 or 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 and program the PCM. With the scan tool, perform QUICK LEARN.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Test Complete.