Fog Lamps Inoperative. Pontiac Grand Prix 2005

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2005 🢒 Grand Prix 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Fog Lamps Inoperative

Fog Lamps Inoperative V6

Step	Action	Yes	No
Schematic Reference: Fog Lights Schematics Connector End View Reference: Power and Grounding Connector End Views in Wiring Systems.
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Turn the ignition to the ON position. Turn the headlamp switch to the PARK position. Place the fog lamp switch in the ON position. Are the fog lamps ON?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Is only one fog lamp inoperative?	Go to Step 4	Go to Step 6
4	Disconnect the inoperative fog lamp. Using a test lamp connected to ground, probe the fog lamps supply voltage circuit of the inoperative fog lamp. Does the test lamp illuminate?	Go to Step 5	Go to Step 22
5	Using a test lamp, probe between the ground circuit and supply voltage circuit of the inoperative fog lamp. Does the test lamp illuminate?	Go to Step 18	Go to Step 24
6	Place the headlamp switch in the HEAD position. Place the headlamp dimmer switch in the high beam position. Do the high beam headlamps operate properly?	Go to Step 7	Go to Headlamps Inoperative - High Beams
7	Check the FOG LP fuse for an open. Is the FOG LP fuse open?	Go to Step 16	Go to Step 8
8	Disconnect the fog lamp relay. Turn the ignition to the ON position. Connect a test lamp between the switch side supply of the fog lamp relay and a ground. Does the test lamp illuminate?	Go to Step 9	Go to Step 20
9	Turn the headlamp switch to the PARK position. Place the headlamp dimmer switch in the low beam position. Connect a test lamp between the coil side supply of the fog lamp relay and a ground. Does the test lamp illuminate?	Go to Step 10	Go to Step 20
10	With the fog lamp switch in the ON position. Connect a test lamp between the coil side supply of the fog lamp relay and the control circuit of the fog lamp relay. Does the test lamp illuminate?	Go to Step 12	Go to Step 11
11	Disconnect the multifunction turn signal switch connector C2 . Connect a jumper between the fog lamp switch signal circuit of the fog lamp switch and ground circuit. Do the fog lamps illuminate?	Go to Step 17	Go to Step 14
12	Connect a fused jumper between the switch side supply of the fog lamp relay and the fog lamps supply voltage circuit of the fog lamp relay. Do the fog lamps illuminate?	Go to Step 19	Go to Step 16
13	Connect a fused jumper between the fog lamp switch signal circuit and ground. Do the fog lamps illuminate?	Go to Step 23	Go to Step 14
14	Test for an open high resistance short to battery positive voltage or a short to ground in the fog lamps switch signal circuit of the fog lamp switch . Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 15
15	Test for an open, high resistance, or short to battery positive voltage in the control circuit of the fog lamp relay . Refer Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 21
16	Test for a short to ground in the fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 20
17	Inspect for poor connections at the harness connector of the fog lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 26
18	Inspect for poor connections at the harness connector of the inoperative fog lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 25
19	Inspect for poor connections at the harness connector of the fog lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 27
20	Inspect for poor connections at the harness connector of the fuse block - underhood. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 28
21	Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 30	Go to Step 29
22	Repair an open or high resistance in the fog lamp supply voltage circuit of the inoperative fog lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Has the repair been made?	Go to Step 30	--
23	Repair a poor connection or an open in the ground circuit of the fog lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Has the repair been made?	Go to Step 30	--
24	Repair an open or high resistance in the ground circuit of the inoperative fog lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Has the repair been made?	Go to Step 30	--
25	Replace the inoperative fog lamp. Refer to Front Fog Lamp Replacement . Has the repair been made?	Go to Step 30	--
26	Replace the multifunction turn signal switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Has the repair been made?	Go to Step 30	--
27	Replace the fog lamp relay. Refer to Relay Replacement in Wiring Systems. Has the repair been made?	Go to Step 30	--
28	Replace the fuse block - underhood. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Has the repair been made?	Go to Step 30	--
29	Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Has the repair been made?	Go to Step 30	--
30	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2

Fog Lamps Inoperative V8

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Front Fog Lamp Control Circuit	2	1	B2530	--
Fog Lamps Inoperative Fog Lamps Always On

Voltage is applied at all times to the fog lamp relay. When the fog lamp switch is placed in the ON position, ground is applied to the body control module (BCM) through the fog lamp switch circuit. The BCM then applies a ground to the front fog lamp control circuit. This engages the fog lamp relay and applies voltage through the fog lamp fuse to the front fog lamps.

Reference Information

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

•	Scan Tool Output Controls

•	Scan Tool Data List

•	Scan Tool Data Definitions

Circuit/System Verification

Ignition ON, turn the park lamps ON. Press the front fog lamp switch. The front fog lamps should illuminate.
Observe the scan tool front fog lamps switch parameter while pressing the fog lamp switch. The reading should change between ON and OFF.

⇒	If the for lamps do not illuminate and the fog lamp switch parameter does not change between ON and OFF when pressing the fog lamp switch--Test input side of BCM for inoperative condition in Circuit/System Testing.

⇒	If the for lamps do not illuminate and the fog lamp switch parameter does change between ON and OFF when pressing the fog lamp switch--Test output side of BCM for inoperative condition in Circuit/System Testing.

Circuit/System Testing

Test Input Side of BCM For Inoperative Fog Lamps

Ignition OFF, disconnect the malfunction turn signal lever harness connector at the switch.
Test for less than 1 ohm of resistance between the ground circuit terminal 3 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Ignition ON, verify the scan tool front fog lamp switch parameter displays OFF.

⇒	If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the body control module.

Install a 3A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 3. Verify the scan tool front fog lamp switch parameter displays closed.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the body control module.

If all circuits test normal, test or replace the multifunction turn signal lever.

Test Output Side of BCM For Inoperative Fog Lamps

Disconnect the harness connector at both fog lamps.
Test for less than 1.0 ohm of resistance between the appropriate fog lamp ground circuit terminal B and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Connect a test lamp between the control circuit terminal A and ground.
Command the fog lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BEC.

⇒	If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the BEC.

⇒	If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the appropriate fog lamp bulb socket.

If all circuits test normal, replace the appropriate fog lamp bulb socket.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Accessory Wiring Junction Block Replacement

•	Front Fog Lamp Bulb Replacement

•	Turn Signal Multifunction Switch Replacement

•	Control Module References for BCM replacement, setup, and programming