The TAP Shift system allows the driver to manually shift gears by using the TAP Shift switches located on the Automatic Transmission Shifter. Pushing the Up switch will command an upshift and pushing the Down switch will command a downshift. The TAP Shift system is activated when the gear selector is in the Low position and is deactivated in all other positions.
If the powertrain control module (PCM) detects TAP enable switch Inactive and the TR switch indicates D3, DTC P1877 sets. DTC P1877 is a type C DTC.
This diagnostic procedure supports the following DTC:
DTC P1877 Up and Down Shift Switch Performance - Range Switch in D3
• | No TAP system DTCs P0815, P0816 or P0826. |
• | No PSA DTCs P1810, P1816, or P1818. |
• | No TAP system performance DTC 1876. |
• | The engine is running for greater than 5 seconds and not in fuel cut off. |
The PCM detects the TAP enable switch is Inactive and the TR switch indicates D3 for 3 seconds 5 times during the same ignition cycle.
The PCM detects the TAP enable switch is Inactive and the TR switch indicates D3 for 60 seconds.
• | The PCM does not illuminate the malfunction indicator lamp (MIL). |
• | The PCM disables TAP shift operation. |
• | The PCM commands an alternate coast shift pattern where downshifts occur at higher speeds while coasting. |
• | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information a Failure Record. |
• | The PCM stores DTC P1877 in PCM history. |
• | A scan tool can clear the DTC. |
• | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring. |
Step | Action | Value(s) | 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 PCM. Does the scan tool Driver Shift Request parameter display None? | -- | Go to Step 3 | |||||||||
3 | Select Driver Shift Request Voltage on the scan tool. Does the Driver Shift Request Voltage parameter display a value higher than specified? | 0.5 V | Go to Step 4 | Go to Step 5 | ||||||||
4 | Does the Driver Shift Request Voltage parameter display a value lower than specified? | 4.5 V | Go to Step 9 | Go to Step 8 | ||||||||
5 |
Refer to Circuit Protection - Fuses . Was the fuse open? | -- | Go to Step 6 | Go to Step 7 | ||||||||
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. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||||
7 | Test the ignition 1 voltage circuit of the A/T Shift Program Switch for an open between the fuse block and the A/T Shift Program Switch. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||||
8 | Test the signal circuit of the A/T Shift Program Switch for an open or short to ground between the A/T Shift Program Switch and the PCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||
9 |
Is the resistance within the specified range? | 8.11-8.39K ohms | Go to Step 11 | Go to Step 10 | ||||||||
10 | Replace the A/T Shift Program Switch. Refer to Transmission Control Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||
11 | Replace the PCM. Refer to Control Module References for replacement, set-up, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 13 | Go to Step 2 | ||||||||
13 | With a 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 |