GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 1999 🢒 S/T Isuzu - 2WD 🢒 Body and Accessories 🢒 Body Control System 🢒 Courtesy or Dome Lamps Inoperative

Step

Action

Value(s)

Yes

No

Important: The CTSY LP fuse in the IP fuse block supplies power to all of the interior lamps through direct wiring or the courtesy lamp relay and the inadvertent power relay. The IP compartment lamp and the underhood lamp do not share the same ground, so the IP compartment lamp and/or the underhood lamp may operate when the other lamps are inoperative.

1

Did you perform the Interior Lights System Check?

--

Go to Step 2

Go to Interior Lamps System Check

2
  1. Turn the ignition switch to the ON position. Do not start the engine.
  2. Use the scan tool in order to inspect for DTCs.

Are any DTCs present?

--

Go to Diagnostic System Check - Body Control System in Body Control System

Go to Step 3

3

Use the scan tool in order to monitor the following components for proper operation. Refer to Scan Tool Data List in Body Control System for more information.

    • The passenger door jamb/door handle switches
    • The driver door jamb switch
    • Key in ignition
    • The courtesy lamp relay
    • The inadvertent power relay
    • The dome override switch
    • The dome lamp switch

Did you locate and correct a condition?

--

Go to Interior Lamps System Check

Go to Step 4

4

Is the CTSY LP 15A fuse (IP fuse 8) open?

--

Go to Step 5

Go to Step 8

5
  1. Disconnect the inadvertent power relay from the body relay block.
  2. Connect a J 39200 DMM between the inadvertent power relay connector terminal 5 to ground.

Is the resistance less than the specified value?

2 ohms

Go to Step 6

Go to Step 7

6

Locate and repair a short to ground in CKT 40 (ORN).

Is the repair complete?

--

Go to Interior Lamps System Check

--

7

Locate and repair a short to ground in CKT 1732 (ORN).

Is the repair complete?

--

Go to Interior Lamps System Check

--

8
  1. Disconnect the inadvertent power relay from the body relay block.
  2. Test for power at terminal 2 of the inadvertent power relay connector.

Is the specified voltage present?

Battery Voltage

Go to Step 10

Go to Step 9

9

Locate and repair an open in CKT 40 (ORN).

Is the repair complete?

--

Go to Interior Lamps System Check

--

10
  1. Install the inadvertent power relay in the body relay center.
  2. Open the left front door.
  3. Deactivate the interior lamp defeat switch.

Do the courtesy lamps and the dome lamps illuminate?

--

Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System

Go to Step 11

11

Open the IP compartment.

Does the IP compartment lamp illuminate?

--

Go to Step 15

Go to Step 12

12

Inspect CKT 1393 (DK BLU) for an open.

Is an open present?

--

Go to Step 14

Go to Step 13

13

Replace the inadvertent power relay.

Is the repair complete?

--

Go to Interior Lamps System Check

--

14

Locate and repair the open in CKT 1393 (DK BLU).

Is the repair complete?

--

Go to Interior Lamps System Check

--

15

Do the power door locks operate properly?

--

Go to Step 17

Go to Step 16

16

Locate and repair an open in CKT 1850 (BLK).

Is the repair complete?

--

Go to Interior Lamps System Check

--

17

Replace the courtesy lamp relay.

Is the repair complete?

--

Go to Interior Lamps System Check

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