P1870

Diagnostic Chart:

CIRCUIT DESCRIPTION

The Vehicle Control Module (VCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with the TCC engaged, the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +50 RPM. The table above indicates solenoid states and transmission components that apply during 4th gear with the TCC commanded ON.

When the VCM detects excessive TCC slip when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type B DTC.

CONDITIONS FOR SETTING THE DTC

DTC P1870 sets if the following conditions are met for three TCC cycles with reported excessive TCC slip conditions, two consecutive times.

^ No TP Sensor DTCs P0122 or P0123.

^ No VSS Assy. DTCs P0502 or P0503.

^ No TFT Sensor DTCs P0711, P0712 or P0713.

^ No TCC Sol. Valve DTC P0740.

^ No 1-2 Shift Solenoid Valve (1-2 SS Valve) DTC P0753.

^ No 2-3 Shift Solenoid Valve (2-3 SS Valve) DTC P0758.

^ No Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) DTC P1810.

^ No Torque Converter Clutch Pulse Width Modulated Solenoid Valve (TCC PWM Sol. Valve) DTC P1860.

^ The engine speed is greater than 450 RPM for 5 seconds.

^ Not in fuel cutoff.

^ The vehicle speed is 48-112 km/h (3070 mph).

^ The engine speed is 1500-3000 RPM.

^ The speed ratio is 0.69-0.88 (speed ratio is engine speed divided by the output speed).

^ The engine torque is 50-400 lb ft.

^ The engine vacuum is 0-150 kPa.

^ The gear range is D4.

^ Not in 1st gear.

^ The TP angle is 9-35%.

^ The TFT is 20-130°C (68-266°F).

^ The shift solenoid performance diagnostic counters are zero.

^ The TCC is ON for 5 seconds.

^ The TCC is at maximum duty cycle (95%) for 5 seconds.

^ The TCC slip speed is 130-800 RPM.

^ All conditions met for 7 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The VCM illuminates the Malfunction Indicator Lamp (MIL).

^ The VCM inhibits TCC engagement.

^ The VCM commands maximum line pressure.

^ The VCM inhibits 4th gear if the transmission is in hot mode.

^ The VCM freezes shift adapts from being updated.

^ DTC P1870 stores in VCM history.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns OFF the MIL after three consecutive trips without a failure reported.

^ A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.

DIAGNOSTIC AIDS

Internal transmission failures could set a DTC P1870.

TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table.

3. This step tests the torque converter for slippage while in a commanded lock-up state.