GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Corvette 🢒 DTC 🢒 DTC P1870 Transmission Component Slipping
Table 1: DTC P1870 Range Reference Thumbnail 4L60-E
Table 2: DTC P1870 Transmission Slipping Component

Object Number: 42275 Size: MF
OBD II Symbol Description Notice
Automatic Transmission Components VIN K

DTC P1870 Range Reference Thumbnail 4L60-E

Range

Gear

Shift Solenoid

TCC Solenoid

TCC PWM Solenoid

2-4 Band

Forward Clutch

3-4 Clutch

Torque Converter Clutch

1-2

2-3

Overdrive

4th

ON

OFF

ON

90% (ON)

Applied

Applied

Applied

Applied

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 +30 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 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 TCC Sol. Valve DTC P0740.
    • No 1-2 SS Valve DTC P0753.
    • No 2-3 SS Valve DTC P0758.
    • No 3-2 SS Valve Assy. DTC P0785.
    • No TCC PWM Sol. Valve DTC P1860.
    • The engine speed is greater than 450 RPM for 8 seconds.
    • Not in fuel cutoff.
    • The vehicle speed is 56-105 km/h (35-65 mph).
    • The speed ratio is 0.67-0.9 (the speed ratio is the engine speed divided by the output speed).
    • The engine speed is 1200-3500 RPM.
    • The engine torque is 40-400 lbs ft.
    • The gear range is D4.
    • Not in 1st gear
    • The TP angle is 10-50%.
    • The TFT is between 20-130°C (68-266°F).
    • TCC is commanded On for 5 seconds.
    • The TCC is at maximum apply for 5 seconds.
    • The shift solenoid performance diagnostic counters are zero.
    • The TCC slip speed is 150-800 RPM.
    • All conditions met for 7 seconds.

Action Taken When the DTC Sets
    • The PCM illuminates the Malfunction Indicator Lamp (MIL).
    • 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.
    • DTC P1870 stores 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
    • Internal transmission failures could set a DTC P1870.
    • A TFP Valve Position Switch malfunction could set a DTC P1870.

Test Description

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

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

DTC P1870 Transmission Slipping Component

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain OBD System Check

2

Perform the transmission fluid checking procedure.

Refer to Transmission Fluid Check .

Was the transmission fluid checking procedure performed?

--

Go to Step 3

Go to Transmission Fluid Check

3
  1. Install the scan tool (tech 1) ®.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.

  3. Record the Freeze Frame and Failure Records.
  4. Clear the DTCs.
  5. With the engine idling and at normal operating temperature, apply the brake pedal.
  6. Select each transmission range: D1, D2, D3, D4, N, R and P.

    7. Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic.

Does each selected transmission range match the scan tool TFP switch A/B/C display?

--

Go to Step 4

Go to Transmission Fluid Pressure Manual Valve Position Switch Resistance Check

4
  1. Install the Scan Tool .
  2. With the engine OFF, turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTC(s), use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM.

  3. Record the DTC Freeze Frame and Failure Records, then clear the DTC(s).
  4. Drive the vehicle in 4th gear with the TCC commanded ON.

Is the TCC Slip Speed between the specified values for 7 seconds?

150-800 RPM

Go to Step 5

Go to Diagnostic Aids

5
  1. Inspect the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) for the following conditions:
    2. • Internal malfunction (such as sediment or damage)
    • Damaged seals
  2. Inspect the Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve) for the following conditions:
    3. • Internal malfunction (such as sediment or damage)
    • Damaged seals

Did you find a condition?

--

Go to Step 14

Go to Step 6

6
  1. Inspect the 1-2 Shift Solenoid Valve (1-2 SS Valve) for the following conditions:
    2. • Internal malfunction (such as sediment or damage)
    • Damaged seals
  2. Inspect the 2-3 Shift Solenoid Valve (2-3 SS Valve) for the following conditions:
    3. • Internal malfunction (such as sediment or damage)
    • Damaged seals

Did you find a condition?

--

Go to Step 14

Go to Step 7

7

Inspect the valve body assembly for a stuck TCC signal valve. Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Step 8

8

Inspect the torque converter assembly for the following conditions:

    • Stator roller clutch not holding
    • Internal damage

Did you find a condition?

--

Go to Step 14

Go to Step 9

9

Inspect the oil pump assembly for the following conditions:

    • Stuck converter clutch valve
    • Converter clutch valve assembled backwards
    • Mispositioned converter clutch valve retaining ring
    • Mispositioned pump to case gasket
    • Restricted orifice cup plugs
    • Damaged orifice cup plugs
    • Over-tightened, or unevenly tightened pump body to cover bolts

Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Step 10

10

Inspect the input housing and shaft assembly for the following conditions:

    • Cut turbine shaft o-ring seal
    • Damaged turbine shaft o-ring seal
    • Restricted turbine shaft retainer and ball assembly
    • Damaged turbine shaft retainer and ball assembly

Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Step 11

11

Inspect the 2-4 band assembly for the following conditions:

    • Worn 2-4 band
    • Damaged 2-4 band
    • Mispositioned 2-4 band
    • Misassembled 2-4 band
    • The band anchor pin is not engaged.
    • Restricted apply passages in the 2-4 servo assembly
    • Blocked apply passages in the 2-4 servo assembly
    • Nicks or burrs on the servo pin
    • Nicks or burrs on the pin bore in the case
    • Damaged fourth servo piston
    • Misassembled fourth servo piston
    • Damaged band apply pin
    • Incorrect band apply pin
    • Damaged servo bore in the case
    • Missing piston seals
    • Cut piston seals
    • Damaged piston seals
    • Porosity in the pistons
    • Porosity in the cover
    • Porosity in the case
    • Damaged piston seal grooves
    • Plugged orifice cup plug
    • Missing orifice cup plug

Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Step 12

12

Inspect the forward clutch assembly for the following conditions:

    • Worn clutch plates
    • Porosity in the forward clutch piston
    • Damaged forward clutch piston
    • Missing forward clutch piston inner and outer seals
    • Cut forward clutch piston inner and outer seals
    • Damaged forward clutch piston inner and outer seals
    • Missing input housing to forward clutch housing o-ring seal
    • Cut input housing to forward clutch housing o-ring seal
    • Damaged input housing to forward clutch housing o-ring seal
    • Damaged forward clutch housing
    • Damaged forward clutch housing retainer and ball assembly
    • Forward clutch housing retainer and ball assembly is not sealing.

Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Step 13

13

Inspect the 3-4 clutch assembly for the following conditions:

    • Worn clutch plates
    • Porosity in the 3-4 clutch piston
    • Damaged 3-4 clutch piston
    • Missing 3-4 clutch inner and outer seals
    • Cut 3-4 clutch inner and outer seals
    • Damaged 3-4 clutch inner and outer seals
    • Damaged 3-4 clutch spring assembly
    • Damaged 3-4 clutch apply ring
    • Damaged piston seal grooves
    • Plugged orifice cup plug
    • Missing orifice cup plug

Refer to Unit Repair.

Did you find a condition?

--

Go to Step 14

Go to Diagnostic Aids

14

In order to verify your repair, perform the following procedure:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Drive the vehicle in D4, with the TCC ON, and a throttle position of 10-50%.
    • Ensure that the TCC Slip Speed is -20 to +30 RPM for at least 7 seconds.
  4. Select Specific DTC. Enter DTC P1870.

Has the test run and passed?

--

System OK

Begin the diagnosis again. Go to Step 1