A/T Controls - P0894/P1870 Diagnostics

Information IB06-05-S002

Diagnostic Information on Diagnostic Trouble Code
(DTC) P0894 and P1870 (This Bulletin Supersedes SB04-05-S008)

ISSUE DATE: JANUARY 30, 2006

Affected Vehicles

2003-2006 Isuzu Ascender (US/UT)
2006 Isuzu i-280/i-350 (TI) with 4L60-E Transmission

Service Information

This bulletin is being revised to update models, model years, and information. Please discard SB04-05-S008.

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.

^ Slip speeds greater than about 400 RPM at steady state driving are usually caused by a slipping clutch or band.

^ Slip speeds ranging from approximately 100 to 400 RPM at steady state driving are usually caused by the TCC not applying but may also be caused by a slipping clutch or band.





^ 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) 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 may also cause DTC P0894 or P1870.

When attempting to diagnose a DTC P0894 or P1870, it is important to also refer to the Service Manual for further information.





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