P1772
P1772 - Inadequate Element Volume OD
For a complete wiring diagram, refer to.
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 OD clutch volume index is updated during a 2-3 upshift with throttle angle between 10 and 54 degrees. Transmission temperature must be at least 43° C (110° F).
• Set Condition: When the OD CVI falls less than a calibrated value.
Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - Other DTCs Present
• With the scan tool, check DTCs.
Are there any pressure switch sense circuit DTCs present also?
Yes
• Refer to the transmission category and perform the appropriate symptom.
No
• Go to Test Step 2.
Test Step 2 - Check the OD Clutch Volume Index
• With the scan tool, erase DTCs.
• 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 2-3 upshifts with the TPS degree between 10 and 54.
• With the scan tool, read the OD CL VOL INDEX.
Is the OD CL VOL INDEX less than 10?
Yes
• Go to Test Step 3.
No
• Go to Test Step 5.
Test Step 3 - OD 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 OD accumulator spring.
• Look for possible leak paths into the OD clutch hydraulics circuit within the valve body.
Were any problems found?
Yes
• Repair as necessary.
• Perform the Transmission Verification Test. Refer to => Non-DTC Based Diagnostics. Transmission Verification Test
No
• Go to Test Step 4.
Test Step 4 - Air Check OD Clutch Circuit
• Perform an air check on the OD Clutch circuit.
• Watch and listen for OD clutch piston movement.
• Air check all other pump passages and watch for air leakage into the OD clutch passage.
• There is a bleed orifice between the OD and reverse clutch passages, so a small amount of air leakage from reverse to OD is normal.
Were any problems found?
Yes
• Repair internal transmission. Pay attention to the OD clutch. Broken or weak return spring or a dislocated snap ring could cause this problem. If no problems were found in the OD clutch, or if leakage into the OD passage was noted, replace pump assembly.
• Perform the Transmission Verification Test. Refer to => Non-DTC Based Diagnostics. Transmission Verification Test
No
• Replace the transmission/TRS solenoid assembly. With the scan tool, perform Quick Learn.
• Perform the Transmission Verification Test. Refer to => Non-DTC Based Diagnostics. Transmission Verification Test
Test Step 5 - Verify PCM Operation
• The TRANS TEMP DEG must be at least 43° C (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 for all clutches.
• With the scan tool, perform a battery disconnect.
• With the scan tool, read the CVIs and compare them to the readings recorded before the battery disconnect.
Are any of the CVIs less than 5 or different than before the battery disconnect?
Yes
• Using the schematics as a guide, check the powertrain control module 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. Refer to With the scan tool, perform Quick Learn.
• Perform the Transmission Verification Test. Refer to => Non-DTC Based Diagnostics. Transmission Verification Test
No
• Test Complete.