6T70, 6T75, 6L50, 6L80 or 6L90 Automatic Transmission - Information on Transmission Fluid Pressure (TFP) Switch Check for False DTCs P0842, P0843, P0872, P0873, P0877, P0878, P0989 or P0990
| Subject: | 6T70, 6T75, 6L50, 6L80 or 6L90 Automatic Transmission -- Information on Transmission Fluid Pressure (TFP) Switch Check For False DTCs P0842, P0843, P0872, P0873, P0877, P0878, P0989 or P0990 |
| Models: | 2008 Buick Enclave |
| 2007 GMC Acadia |
| 2007 Pontiac G6 |
| 2007 Saturn AURA, OUTLOOK |
| with 6T70 or 6T75 Automatic Transmission (RPOs MH2, MH4, MH6, MY9) |
| 2006 Cadillac STS-V, XLR-V |
| 2007 Cadillac Escalade, Escalade ESV, Escalade EXT, SRX, STS, STS-V, XLR, XLR-V |
| 2006-2007 Chevrolet Corvette |
| 2007 Chevrolet Silverado |
| 2007 GMC Sierra, Yukon Denali, Yukon Denali XL |
| with 6L50, 6L80, or 6L90 Automatic Transmission (RPOs MYB, MYC, MYD) |
During diagnosis of various transmission symptoms and diagnostic codes, technicians may see DTCs P0842, P0843, P0872, P0873, P0877, P0878, P0989 or P0990 indicating an issue with transmission fluid pressure (TFP) switches.
During normal use, the TFP switches may stick from time to time causing a code to set. This is to be considered normal as switch outputs are only used for shift adaptives and do not cause transmission symptoms unless the switch is failed for a long period of time.
To determine if the TFP switch is functioning correctly, clear the code and perform the following check.
Important: The Tech 2® must contain version 27.007 or later.
- Turn the key to the "ON" position (do not start), apply parking brake and put vehicle in neutral.
- Plug the Tech 2® into the ALDL and turn power on.
- Press "enter" on the Tech 2® to get to the first menu.
- Select "Diagnostics" from the first menu.
- From the following screens, build the vehicle.
- Select "Powertrain."
- Select the correct engine.
- Select "Transmission Control Module."
- Select "Special Functions."
- Select "Shift Transmission."
- Scroll down until you can see all pressure switch state variables (TFP 1, 3, 4 and 5). All switches should read "LOW" at key on (in neutral). Refer to the table below.
- Apply the foot brake, start the vehicle leaving it in neutral and compare the switch states to row 2 of the table. Make sure to allow enough time for the switches to stabilize.
- With the brakes applied, place the shifter in drive (D) (IMS Drive 6) and shift the transmission into 2nd gear using the Tech 2® soft key (upshift or downshift). The commanded gear is displayed at the top of the screen. Compare with variables in the table.
- Keep the vehicle in drive (D) (IMS Drive 6) and shift to 5th gear using the Tech 2® soft key (upshift or downshift). Compare with variables in the table.
Important: Make sure to wait for at least 5 seconds in each gear state for the TFPs to stabilize.
If the TFP switch states match the values in the table for all listed gear states, the switches are functioning correctly. Any switch codes that set were caused by an intermittent condition that will not cause transmission related driveability concerns.
Commanded Gear | TFP Switch 1 P0842 (LOW) P0843 (HIGH) | TFP Switch 3 P0872 (LOW) P0873 (HIGH) | TFP Switch 4 P0877 (LOW) P0878 (HIGH) | TFP Switch 5 P0989 (LOW) P0990 (HIGH) |
|---|---|---|---|---|
N -- Key Off | LOW | LOW | LOW | LOW |
N -- Engine On | HIGH | LOW | LOW | LOW |
2 | HIGH | LOW | LOW | HIGH |
5 | LOW | HIGH | HIGH | LOW |
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation | Description | Labor Time |
|---|---|---|
K9514* | Clear Code and Perform Transmission Fluid Pressure (TFP) Switch Check | 0.3 hr |
* This is a unique labor operation number for bulletin use only. This number will not be published in the Labor Time Guide. | ||
