Circuit Description
The automatic transmission fluid pressure (TFP) manual valve position switch consists of three pressure switches. Two of the switches are normally-open, and determine gear range selection. The third switch is normally-closed, and detects torque converter clutch (TCC) release fluid pressure. The TFP manual valve position switch also contains the automatic transmission fluid temperature (TFT) sensor. These components are combined into one unit, attached to the control valve body.
The transmission control module (TCM) provides battery voltage on the two range signal circuits. By grounding one or more of the switches with fluid pressure from the manual shift valve, the TCM detects the selected gear range. When you disconnect the transmission electrical connector and the ignition is ON, the ground potential for the range signals from the TCM will be removed, and an invalid gear range will be indicated. Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic .
When the TCM detects P/N indicated with a drive gear ratio, DTC P1816 sets. DTC P1816 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1816 Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Park/Neutral (P/N) with Drive Ratio
Conditions for Running the DTC
| • | No TP DTCs P0120 or P0220. |
| • | No ISS DTCs P0716 or P0717. |
| • | No OSS DTCs P0722 or P0723. |
| • | No SS valve performance DTCs P0751, P0752, P0756, or P0757. |
| • | No SS valve electrical DTCs P0973 or P0974, P0976, or P0977. |
| • | The engine is running for 5 seconds. |
| • | The calc. throttle position is between 8 percent and 90 percent. |
| • | The engine torque is greater than 50 N·m (37 lb ft). |
| • | The output speed is 250 RPM or more. |
Conditions for Setting the DTC
The TCM detects P/N with a drive ratio for 6 seconds.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records. |
| • | The TCM stores DTC P1816 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | The TCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear DTC Information function erases the Failure Records from the TCM. Does the scan tool TFP Sig. B/Sig. C parameter indicate HI for both? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
Does the TFP Sig. B indicate LOW? | Go to Step 5 | Go to Step 4 | |
4 | Test the TFP signal B circuit of the TFP manual valve position switch for an open between the TCM and the AT inline 20-way connector. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct a condition? | Go to Step 9 | Go to Step 8 |
5 | Test the TFP signal B circuit of the TFP manual valve position switch for an open between the AT inline 20-way connector and the TFP manual valve position switch. Refer to Testing for Continuity . Did you find and correct a condition? | Go to Step 6 | Go to Step 7 |
6 | Replace the automatic transmission wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement? | Go to Step 9 | -- |
7 | Replace the TFP manual valve position switch. Refer to Transmission Fluid Pressure Manual Valve Position Switch Replacement . Did you complete the replacement? | Go to Step 9 | -- |
8 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Is the replacement complete? | Go to Step 9 | -- |
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 10 | Go to Step 2 |
10 | With the scan tool, observe the stored information, capture info, and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | System OK |
