Info - New Tech 2 TCC Test/Component Slipping/DTC P1870

General Motors Powertrain (GMPT) has designed a new Tech 2 test to assist technicians in diagnosing 4L60-E automatic transmissions with a DTC P1870 (Transmission Component Slipping). This DTC P1870 test is designed to identify intermittent faults in the torque converter clutch system. There are a number of internal mechanical failures outside of the torque converter clutch system that could cause this test to fail. For these failure modes, please refer to Corporate Bulletin Number 99-07-30-005 (Section 7 -- Transmission).

This test is accomplished by the Tech 2 commanding lock up of each TCC solenoid to full capacity, while the vehicle is in drive and the parking brake is applied. The new DTC P1870 diagnostic test will be available from Techline starting September 1999, on the TIS 2000 Disc 19 CD ROM or the Techline Disc 18/19 CD ROM.

Important: This test should be run on vehicles setting a DTC P1870 with no other associated DTC's. If any other associated DTC's are set along with a DTC P1870, then diagnose those DTC's first.

It is critical that a normal operating temperature of 82°C (180°F) to 93°C (200°F) be reached. It may be difficult to attain this transmission temperature, so allow the vehicle to idle or test drive the vehicle in order to warm the powertrain.

1. Install the Tech 2 to the vehicle and power on.
2. Select the "Diagnostic" selection from the Tech 2 menu.
3. Select the appropriate parameters from the proceeding Tech 2 screens to identify your vehicle:

•	Model Year

•	Light Duty Truck

•	Powertrain

•

Engine

•	Body Style

•	4 Speed Automatic

4. Select "Special Functions" from the Tech 2 menu.
5. Select "Transmission Output Controls" from the Tech 2 menu.
6. Select "P1870 Diagnostic Test" from the Tech 2 menu.
7. After the "P1870 Diagnostic Test" has been selected from the Tech 2 menu, the following screen will be displayed:



8. After the vehicle parameters are within specifications, select [ENTER] and "Test in Progress" will flash at the bottom of the Tech 2 screen.

Important: If the vehicle is not within the following parameters, the test will automatically abort. The Tech 2 will indicate which parameter is not within the following specifications:

•	Engine Speed should be between 800-1200 RPM

•	TP Angle should be 5%

•	Transmission Fluid Temperature should be between 16°C (60°F) to 103°C (218°F)

9. The following screens will be displayed if the vehicle is not within one of the above parameters:



10. Or



11. Or



12. Or

After the test has run, the Tech 2 will display one of the following screens:

Or

Or

Vehicles with a test passed" result should experience an engine sag, stumble, or stall, this is due to the Tech 2 applying both TCC solenoids to full capacity during the test. Vehicles with a test failed" result should not experience an engine sag, stumble or stall. A "Test Failed" result would indicate that there is most likely an internal transmission condition related to items that could cause a DTC P1870 to set. An indeterminate test would result in a vehicle retest request.

Important: If the vehicle has passed an initial test, but the vehicle is suspected to have an intermittent or indeterminate condition, it is recommended that the test be run multiple times at higher transmission temperatures. Running this test multiple times will help technicians duplicate an intermittent DTC P1870.

Refer to the appropriate Service Manual for replacement procedures.

Labor Code: Refer to the Labor Time Guide for the correct labor operation. Please use the closest available labor operation for the diagnosis performed.