08-07-30-008: Diagnostic Information on Diagnostic Trouble Code (DTC) P0894 and P1870 - (Feb 26, 2008)
Subject: Diagnostic Information on Diagnostic Trouble Code (DTC) P0894 and P1870
Models: 2002-2007 GM Passenger Cars with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32 or M70)
Diagnostic trouble codes (DTC) P0894 and P1870, Transmission Component Slipping, may have different root causes. The following diagnostic tips are provided to assist in accurately repairing the condition.
• Corporate Bulletin Number 06-07-30-007 is intended for 2006 vehicles only. This bulletin provides diagnostic procedures to determine if the TCC enable solenoid is cracked.
• Slip speeds ranging from approximately 100 to 400 RPM at steady state light load driving are usually caused by the TCC not applying.
• Slip speeds greater than about 400 RPM at steady state driving are usually caused by a slipping clutch or band. Inspect the oil pan for the presence of excess clutch debris.
• A plugged or restricted TCC apply fluid orifice (238, located in the pump) may cause DTC P0894 or P1870, especially in low mileage vehicles with less than 8,000 km (5,000 mi).
• A converter clutch valve (224, located in the pump), which does not have full travel of 13 mm (0.5 in) or is stuck in the off position may cause DTC P0894 or P1870. Inspect the valve for chips, debris, nicks or burrs.
Also, inspect the springs (225 and 226) to make sure they are not limiting valve travel. A spring that is not fully wound may catch in the bore, limit valve travel and cause DTC P0894 or P1870.
• A cracked or leaking TCC solenoid (part of harness 66) may cause DTC P0894 or P1870. Use solenoid test kit J 44246 to test the operation of this solenoid.
• A cracked or leaking TCC PWM solenoid (396) may also cause DTC P0894 or P1870.
• If the vehicle has 24,000 miles (38,600 km) or more, and diagnostics have not determined another cause of the DTC, the torque converter should be replaced.
When attempting to diagnose a DTC P0894 or P1870, it is important to also refer to the appropriate Service Information (SI) document for further possible causes of this condition.