GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Tracker - 2WD 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 4 Speed-M41 🢒 Power Mode Indicator Always On

Circuit Description

When the ignition switch turns ON, the Powertrain Control Module (PCM) performs a 3-second POWER indicator bulb check. The PCM performs the bulb check by grounding the POWER indicator control circuit. The Power/Normal switch button grounds the shift mode signal circuit to the PCM when the Power/Normal switch sets to POWER. The above condition causes the PCM to ground the POWER indicator control circuit. Grounding the POWER indicator control circuit turns on the POWER indicator lamp located in the instrument panel gauge cluster. The POWER indicator informs the driver that the PCM is using the Power gear shift schedule (delaying upshifting for improved acceleration). The PCM dims the POWER indicator lamp by adding additional internal resistance to the POWER indicator control output circuit when both of the following conditions occur:

    • The POWER indicator remains on.
    • The parking lamps/headlamp remain on.

Dimming the POWER indicator lamp reduces excessive glare to the driver at night. The following conditions occur after the Power/Normal switch button sets to NORMAL:

    • The Power/Normal switch button removes a path to ground to the shift mode signal circuit.
    • The PCM turns off the POWER indicator lamp.
    • The PCM uses the Normal gear shift schedule (early upshifting for improved fuel economy).

Diagnostic Aids

Inspect for the following conditions:

    • A short to ground in the POWER indicator control circuit between the PCM and the instrument panel gage cluster.
    • A short to ground in the shift mode signal circuit between the Power/Normal switch and the PCM.
    • A faulty Power/Normal switch (staying closed at all times).
    • A faulty PCM

Rubbed through wire insulation may cause an intermittent condition. Repeat the Powertrain OBD System Check after making repairs in order to ensure that the system functions normally.

Refer to Wiring Repairs in Wiring Systems when repairing any wiring.

Test Description

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

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. The scan tool creates an electronic copy of the data taken when the fault occurred. The information then stores in the scan tool for later reference.

    2.

  2. This step tests for a short to ground in the Shift Mode Signal circuit.

    3.

  3. This step tests for the following conditions:

    4. • A short to ground or a constantly-closed Shift Mode Switch.
    • A faulty PCM.

  4. This step tests for the following conditions:

    5. • A short to ground in the Shift Mode signal circuit.
    • A faulty shift program switch.

  5. This step tests for proper operation of the POWER indicator.

Step

Action

Yes

No

1

Was the On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 2.0L or Diagnostic System Check - Engine Controls in Engine Controls - 2.5L

2

  1. Install a scan tool.
  2. Turn ON the ignition, leaving the engine off.
  3. Monitor the Mode Select Switch status on the scan tool while toggling the shift program switch.

Did the scan tool show the Mode Select Switch status toggle from POWER to NORMAL?

Go to Step 5

Go to Step 3

3

  1. Turn the ignition switch to the LOCK position.
  2. Connect a test lamp between B+ and the PCM harness connector C1 terminal 31.

Does the test lamp turn on?

Go to Step 4

Go to Step 6

4

  1. Disconnect the overdrive switch.
  2. Connect a test lamp between B+ and the PCM harness connector C1 terminal 33.

Does the test lamp turn on?

Go to Step 8

Go to Step 7

5

Repair the short to ground in the GRY/BLU wire between the PCM and the instrument panel gage cluster.

Is the repair complete?

Go to Step 9

--

6

Replace the PCM. Refer to one of the following procedures:

    •  Powertrain Control Module Replacement in Engine Controls - 2.0L
    •  Powertrain Control Module Replacement in Engine Controls - 2.5L

Is the procedure complete?

Go to Step 9

--

7

Replace the shift program switch.

Is the procedure complete?

Go to Step 9

--

8

Repair the short to ground in the ORN/BLU wire between the shift program switch and the PCM.

Is the repair complete?

Go to Step 9

--

9

  1. Turn the ignition switch to the LOCK position.
  2. Reconnect the connector(s).
  3. Turn the ignition switch to the ON position.

Does the POWER indicator lamp operate properly?

System OK

Go to Step 1