With Powertrain Control Module

Wiring Diagram:

CIRCUIT DESCRIPTION

The Powertrain Control Module (PCM) monitors the engine speed, and the transmission output shaft speed. The PCM calculates turbine shaft speed and Torque Converter Clutch (TCC) slip speed by using inputs from the transmission Input Shaft Speed (ISS) Sensor, Transmission Output Shaft Speed (OSS) Sensor and other transmission components. The forward clutch housing is used as the ISS Sensor rotor. Whenever the TCC is engaged, engine speed and turbine speed will closely match, indicating low TCC slip speed. In D3 with the TCC engaged, calculated transmission component slip can only occur in the torque converter. In D4 Overdrive with the TCC engaged, transmission component slip can occur in the TCC or the fourth clutch assembly.

If the PCM detects an excessive TCC slip speed in D4 Overdrive, when the TCC should be engaged, then DTC P187O sets. DTC P1870 is a type D DTC. For California emissions vehicles, DTC P1870 is a type B DTC.

CONDITIONS FOR SETTING THE DTC

^ No MAP DTCs P0106, P0107 or P0108.

^ No Engine Speed DTC P0335.

^ No A/T ISS Sensor DTCs P0716 or P0717.

^ No OSS Sensor DTCs P0722 or P0723.

^ No Torque Converter Clutch Pulse Width Modulated Solenoid Valve (TCC PWM Sol. Valve) DTCs P0741, P0742, or P1860.

^ No 1-2 Shift Solenoid Valve (1-2 SS Valve) DTCs P0751 or P0753.

^ No 2-3 Shift Solenoid Valve (2-3 SS Valve) DTCs P0755 or P0758.

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

^ The gear range is D4.

^ The APP Angle is 12-80%.

^ The TFT is +20 to +130°C (68°-266°F).

^ The engine speed is 1200-3750 RPM.

^ System voltage is 9.0-16.0 volts.

^ The vehicle speed is 48-176 km/h (30-110 mph).

^ The engine torque is 75-352 N.m (60-265 lb. ft).

The above conditions are met, with 4th gear commanded and the TCC ON and one of the following conditions occur:

Condition 1 (after 3 Occurrences)

The PCM detects a slip speed of 120-525 RPM for greater than 5.0 seconds.

Condition 2 (In the following sequence for one occurrence)

1. The PCM detects a TCC Slip Speed of 110-500 RPM for 10 seconds.

1.1. The PCM commands maximum line pressure.

1.2. The PCM freezes shift adapts.

2. The PCM detects a TCC Slip Speed of 110-500 RPM for 10 seconds.

2.1. The PCM commands the TCC OFF for 1.5 seconds.

2.2. The PCM commands the TCC ON.

3. The PCM detects a TCC Slip Speed of 110-500 RPM for 10 seconds.

ACTION TAKEN WHEN THE DTC SETS

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

^ The PCM commands maximum line pressure.

^ The PCM inhibits the TCC engagement.

^ The PCM inhibits 4th gear it in hot mode.

^ The PCM freezes shift adapts.

^ DTC P8170 is stored in PCM history.

CONDITIONS FOR CLEARING THE MIL/DTC

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

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

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

DIAGNOSTIC AIDS

^ A TFP Val. Position Sw. malfunction can set DTC P1870.

^ Internal transmission failures can result in a DTC P1870.

^ Sticking shift valves or contamination may cause intermittent slipping in D4.

^ First diagnose and clear any engine DTCs that are present. Then inspect for any transmission DTCs that may have reset.

^ DTC P186O TCC PWM Solenoid Circuit Electrical (Diesel) can cause a DTC 1870 to set. Diagnose the electrical codes first.

TEST DESCRIPTION

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

3. This step tests the indicated range signal to the actual selected range. A faulty TFP Valve Position Switch can set a DTC P1870.

4. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present.

5. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear.

6. This step tests for a sticking TCC shift valve.

8. This step tests for proper transmission line pressure.