GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T65-E 🢒 Shift Select System Diagnosis

Object Number: 644306 Size: MF
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The shift select system allows the driver to select one of two shift patterns, NORMAL or PERFORMANCE. The PERFORMANCE / NORMAL switch is a normally open switch, that when closed, provides a ground path to the powertrain control module (PCM). When the PCM receives the ground signal, it switches into the PERFORMANCE mode and the following changes occur:

    • Upshifts occur at a higher engine speed.
    • Downshifts occur at a lower percentage throttle position.
    • Engine torque output is increased in 2nd and 3rd gear.

Diagnostic Aids
    • Inspect the connectors at the PCM, the PERFORMANCE / NORMAL switch and all other circuit connecting points for an intermittent condition.
        Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Inspect the circuit wiring for an intermittent condition.
        Refer to Testing for Electrical Intermittents in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step verifies that the Performance/Normal Switch is functioning properly.

    2.

  2. This step determines if a condition exists in circuit 1550.

Shift Select System Diagnosis

Step

Action

Value(s)

Yes

No

1
  1. Install a Scan Tool .
  2. Turn ON the ignition with the engine OFF.
  3. Monitor the Shift Mode on the Scan Tool while toggling the Performance/Normal switch.

Does the Scan Tool indicate Normal and Performance appropriately?

--

Go to Symptom Diagnosis

Go to Step 2

2
  1. Disconnect the Performance/Normal Switch.
  2. Connect a fused jumper between terminal A and terminal B of the switch connector.
  3. Turn ON the ignition with the engine OFF.

Does the Shift Mode status on the Scan Tool change?

--

Go to Step 8

Go to Step 3

3
  1. Connect a fused jumper from terminal A of the switch connector to a known good ground.
  2. Turn ON the ignition with the engine OFF.

Does the Shift Mode status on the Scan Tool change?

--

Go to Step 7

Go to Step 4

4

Does the Shift Mode parameter on the Scan Tool always display Performance?

--

Go to Step 5

Go to Step 6

5

Inspect the input circuit (CKT 1493) for a short to ground.

Was a condition found?

--

Go to Step 10

Go to Step 9

6

Inspect the input circuit (CKT 1493) for an open.

Was a condition found?

--

Go to Step 10

Go to Step 9

7

Inspect the ground circuit (CKT 1550) for an open.

Was a condition found?

--

Go to Step 10

Go to Diagnostic Aids

8

Replace the Performance/Normal switch.

Is the replacement complete?

--

Go to Step 11

--

9

Replace PCM.

Refer to Powertrain Control Module Replacement/Programming in Engine Controls.

Is the replacement complete?

--

Go to Step 11

--

10

Repair the circuit as necessary.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

11
  1. Road test the vehicle using the Normal shift mode and the Performance shift mode.
  2. Observe Shift Mode on the Scan Tool to verify that the mode changes as commanded.

Does the vehicle operate properly?

--

System OK

Go to Step 1