For 1990-2009 cars

### 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:

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

### Diagnostic Aids

Inspect for the following conditions:

• | An open POWER indicator lamp bulb filament.

• | An open IG COIL fuse

• | A faulty Power/Normal switch (always open)

• | A poor ground (G200)

• | An open circuit between the PCM and the instrument panel gauge cluster

• | A damaged instrument panel gauge cluster printed circuit

• | A faulty PCM

The following conditions may cause an intermittent condition:

• | A poor connection

• | Rubbed through wire insulation

• | A broken wire inside the insulation

Before replacing components, inspect the inline harness connector terminals for the following conditions:

• | Poor connections

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Reduced terminal-to-wire connections.

Repeat the Powertrain OBD System Check after making repairs in order to ensure that the system functions normally.

Refer to Wiring Repairs in Wirng 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. This step verifies that the PCM performs the bulb check.

3. This step tests the integrity of the indicator control circuit.

4. This step inspects for an open bulb filament.

5. This step tests the power source to the instrument panel gauge cluster.

6. This step tests for an open in the indicator control circuit.

7. This step determines if the PCM responds by turning on the POWER indicator when grounding the POWER signal circuit.

8. This step tests for a reduced ground (G200) to the Power/Normal switch.

9. This step tests for a faulty Power/Normal switch.

   See the above figure.

10. This step verifies if the condition relates to a poor connection and not due to a faulty PCM.

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls
2 |

1. Turn the Power/Normal switch to the Power (P) position.
2. Turn the ignition switch to the ON position.

Did the POWER indicator lamp turn on for at least 3 seconds?

--

Go to Step 7

Go to Step 3

3 |

1. Turn the ignition switch to the LOCK position.
2. Connect a fused jumper between ground and the PCM harness connector C3 terminal 7.
3. Turn the ignition switch to the ON position.

Does the POWER indicator lamp turn on?

--

Go to Step 10

Go to Step 4

4 |

1. Turn the ignition switch to the LOCK position.
2. Remove the instrument panel gauge cluster.
3. Remove the POWER indicator bulb from the cluster.

Is the bulb filament open?

--

Go to Step 11

Go to Step 5

5 |

1. Disconnect the instrument panel gauge cluster connector C1.
2. Turn the ignition switch to the ON position.
3. Connect a test lamp between ground and the instrument panel gauge cluster harness connector C1 terminal 2.

Does the test lamp turn on?

--

Go to Step 6

Go to Step 12

6 | Use J 39200 in order to measure the resistance between the instrument panel gauge cluster harness connector C1 terminal 11 and the PCM harness connector C3 terminal 7. Is the resistance less than the specified value? | 2 ohms | Go to Step 13 | Go to Step 14
7 |

1. Turn the ignition switch to the LOCK position.
2. Connect a fused jumper wire between ground and the PCM harness connector C3 terminal 4 by backprobing.
3. Turn the ignition switch to the ON position.

Does the POWER indicator lamp remain on after the 3 second bulb check?

--

Go to Step 8

Go to Step 10

8 |

1. Turn the ignition switch to the LOCK position.
2. Disconnect the Power/Normal switch.
3. Connect a test lamp between B+ and the Power/Normal switch connector 4.

Does the test lamp turn on?

--

Go to Step 9

Go to Step 15

9 | Use the J 39200 in order to measure the resistance across the Power/Normal switch terminals. Is the resistance less than the specified value in the P position? | 2 ohms (∞ with the Switch in the (N) position) | Go to Step 17 | Go to Step 16
10 | Inspect the PCM connector C3 for poor terminal contact. Replace the PCM if terminal contact is OK. Is the procedure complete? | -- | Go to Step 18 | --
11 | Replace the POWER indicator bulb. Is the replacement complete? | -- | Go to Step 18 | --
12 | Repair the open or the high resistance in the BLK/WHT wire between the instrument panel gauge cluster and the IG COIL fuse. Is the repair complete? | -- | Go to Step 18 | --
13 | Inspect the instrument panel gauge cluster printed circuit for cracks or opens. Replace the instrument panel gauge cluster as necessary. Is the procedure complete? | -- | Go to Step 18 | --
14 | Repair the open or the high resistance in the PNK wire between the instrument panel gauge cluster and the PCM. Is the repair complete? | -- | Go to Step 18 | --
15 | Repair the open or the high resistance in the BLK wire between the Power/Normal switch harness connector terminal 4 and G200. Is the repair complete? | -- | Go to Step 18 | --
16 | Replace the Power/Normal switch. Refer to Power/Normal (P/N) Switch Replacement . Is the procedure complete? | -- | Go to Step 18 | --
17 | A malfunction does not exist at this time. Refer to Diagnostic Aids for additional information. Is the action complete? | -- | Go to Step 18 | --
18 |

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 turn on for approximately 3 seconds?

(The indicator will remain ON with the Power/Normal switch in the Power (P) position).

--

System OK

Go to Step 1