Circuit Description
The transmission adaptive pressure (TAP) up/down shift system allows the driver to manually shift gears by using the TAP shift switch located on the automatic transmission shift lever. Pushing the switch forward will command an upshift and pushing the switch rearward will command a downshift. The TAP shift system is activated when the gear selector is in the manual (M) position.
DTC P0827 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0827 TAP Up and Down Shift Switch Circuit Low
Conditions for Running the DTC
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | The engine, input, speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds. |
| • | The output speed is greater than 200 RPM. |
| • | Driver shift request is commanded. |
Conditions for Setting the DTC
DTC P0827 sets when the transmission control module (TCM) detects a short to ground condition in the TAP up/down shift switch circuit for greater than 6 seconds when driver shift request is commanded.
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. |
| • | DTC P0827 is stored in TCM history. |
| • | The TCM disables driver shift request operations. |
Conditions for Clearing the MIL/DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: |
| - | A bent terminal |
| - | A backed-out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | You may have to drive the vehicle in order to experience a condition. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests signal voltage to the TCM.
-
This step tests supply voltage to the driver shift request switch.
-
This step tests resistance of the driver shift request switch.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
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 Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Is the voltage within the specified range? | 9-18 V | Go to Step 3 | Go to DTC P0562 for low voltage or DTC P0563 for high voltage |
Is the voltage within the specified value? | 2.5 V | Go to Diagnostic Aids | Go to Step 4 | |
Is the voltage within the specified range? | 11.75-12.75 V | Go to Step 5 | Go to Step 6 | |
Is the resistance within the specified value? | OFF: 6.84 K ohms Tap up: 1.87 K ohms Tap down: 3.97 K ohms | Go to Step 7 | Go to Step 9 | |
6 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics for complete circuit distribution.
Was the fuse open? | -- | Go to Step 11 | Go to Step 7 |
7 | Test the signal circuit of the AT driver shift request switch for a short to ground between the AT driver shift request switch and the TCM. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
8 | Test the ignition 0 voltage circuit of the AT driver shift request switch for a short to ground between the fuse block and the AT driver shift request switch. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | -- |
9 | Replace the AT driver shift request switch. Refer to Shift Lever Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 |
Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 11 | -- |
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 |
12 | 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 | |
