P1870
DTC P1870 Transmission Component Slipping (2.2L)
DTC P1870 Range Reference Thumbnail 4L60-E
Circuit Description
The powertrain control module (PCM) 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 +60 RPM. The table above indicates solenoid states and transmission components that apply during 4th gear with the TCC commanded ON.
When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type B DTC.
Conditions for Running the DTC
- No TP sensor DTCs P0122 or P0123.
- No VSS assembly DTCs P0502 or P0503.
- No TCC solenoid valve DTC P0740.
- No 1-2 SS valve DTC P0753.
- No 2-3 SS valve DTC P0758.
- No 3-2 SS valve assembly DTC P0785.
- No TCC PWM solenoid valve DTC P1860.
- The engine speed is greater than 450 RPM for 5 seconds.
- The engine is not in fuel cutoff.
- The vehicle speed is 56-105 km/h (35-65 mph).
- The speed ratio is 0.64-0.95 (the speed ratio is the engine speed divided by the transmission output speed).
- The engine speed is 1500-3500 RPM.
- The engine torque is 40-400 lb ft.
- The gear range is D4.
- The commanded gear is not 1st gear
- The TP angle is 12-50%.
- The TFT is between 20-130 °C (68-266 °F).
- The shift solenoid performance diagnostic counters are zero.
Conditions for Setting the DTC
DTC P1870 if the following conditions occur for three TCC cycles during the same trip.
- The TCC is commanded ON for 5 seconds.
- The TCC is at maximum duty cycle for 5 seconds.
- The TCC slip speed is 300-1000 RPM for 7 seconds.
Important: The following actions may occur before the DTC sets.
If the TCC is commanded ON and at maximum duty cycle for 5 seconds, the TP angle is 7-40%, and the transmission slip counter has incremented to either 1 or 2 (out of 3 to increment the fail counter for the current ignition cycle), then the following slip conditions and actions may increment the fail counter for the current ignition cycle:
These conditions must occur sequentially.
Condition 1
If the TCC slip speed is 200-1000 RPM for 7 seconds, then the PCM will command maximum line pressure and freeze shift adapts from being updated.
Condition 2
If Condition 1 is met and the TCC slip speed is 200-1000 RPM for 7 seconds, then the PCM will command the TCC OFF for 1.5 seconds.
Condition 3
If Condition 2 is met and the TCC slip speed is 200-1000 RPM for 7 seconds, then the fail counter on the current ignition cycle is incremented.
The above slip conditions and actions may be disregarded if the TCC is commanded OFF at any time as a result of a driving maneuver (sudden acceleration or deceleration).
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
- The PCM inhibits TCC engagement.
- The PCM commands maximum line pressure.
- The PCM inhibits 4th gear if the transmission is in hot mode.
- The PCM freezes shift adapts from being updated.
- The PCM stores DTC P1870 in PCM history during the second consecutive trip in which the conditions for setting the DTC are met.
Conditions for Clearing the MIL/DTC
- The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
- A scan tool clears the DTC from PCM history.
- The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
- The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.
Diagnostic Aids
Internal transmission failures may set DTC P1870.
Test Description
Steps 1 - 2:
Steps 3 - 4:
Steps 5 - 7:
Steps 8 - 9:
Step 10:
Step 11:
Step 12:
Step 13:
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.