Front Fog Lamps Malfunction
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Front Fog Lamps Malfunction
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Headlamp Switch Reference Voltage
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B257B 03
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B257B 03
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-
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-
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Headlight Switch Signal
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B257B 03
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B257B 03
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B257B 07
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-
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Fog Lamp Relay Control
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B2530 02
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1
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2
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-
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Front Fog Lamp Control
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1
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1
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2
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-
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Right Front Fog Lamp Ground
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-
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3
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-
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-
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Left Front Fog Lamp Ground
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-
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4
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-
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-
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1. Front fog lamps inoperative
2. Front fog lamps always ON
3. Right front fog lamp inoperative
4. Left front fog lamp inoperative
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Circuit/System Description
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The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps. With the front fog lamp switch activated the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the front fog indicator.
Schematic Reference
Fog Lights Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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1.
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Ignition ON, observe the scan tool Front Fog Lamps Switch parameter. The parameter should change between Active and Inactive each time the front fog lamp switch is pressed.
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2.
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If the value does not change, refer to Front Fog Lamp Switch Malfunction.
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3.
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Command the Fog Lamps ON and OFF with a scan tool. The front fog lamps should turn ON and OFF when changing between the commanded states.
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4.
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If the front fog lamps are always ON or always OFF, refer to Front Fog Lamps Malfunction.
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Front Fog Lamp Switch Malfunction
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1.
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Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
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2.
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Ignition ON, test for B+ between the B+ reference circuit terminal 1 and ground.
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3.
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If less than the specified range, test the B+ reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
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4.
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Connect a 3A fused jumper wire between the B+ reference circuit terminal 1 and the signal circuit terminal 12. Verify the scan tool Front Fog Lamps Switch parameter is Active.
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5.
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If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9™BCM
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6.
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If all circuits test normal, eplace the S30 headlamp switch.
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Front Fog Lamps Malfunction
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1.
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Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
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2.
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Connect a test lamp between B+ and the control circuit terminal 17.
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3.
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Ignition ON, 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.
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4.
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If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.
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5.
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If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
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6.
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Ignition OFF, connect the X2 harness connector at the X50A underhood fuse block.
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7.
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Disconnect the harness connector at the appropriate E29 fog lamp-front.
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8.
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Test for less than 30 Ω between the ground circuit terminal B and ground.
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9.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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10.
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Connect a test lamp between the control circuit terminal A and ground.
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11.
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Ignition ON, 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.
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12.
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If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the X50A underhood fuse block.
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13.
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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, replace the X50A underhood fuse block.
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14.
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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 E29 fog lamp-front.
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15.
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If all circuits test normal, replace the E29 fog lamp-front.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
