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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Headlight Switch 12V Reference
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1
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1
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1
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-
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Headlight Switch Signal
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1
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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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B2520 01
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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 information on diagnostic tools
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Circuit/System Verification
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•
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Ignition ON, perform the Front Fog Lamps Relay test. The front fog lamps should be ON/OFF.
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•
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Ignition ON, perform the instrument cluster All Indicators test ON and OFF test. The front fog indicator should be ON/OFF.
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Front Fog Lamps Malfunction
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1.
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Ignition OFF, disconnect the appropriate harness connector at the front fog lamps listed below:
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•
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E29LF Fog Lamp - Left Front
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•
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E29RF Fog Lamp - Right Front
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2.
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Test for less than 5 Ω between the appropriate front fog lamp ground circuit harness connector terminal 1 and ground.
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Remove the F48 fuse. Verify that the front fog lamps do not illuminate.
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5.
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If any front fog lamp illuminates, test the signal X50A Fuse Block - Underhood circuit terminal 31 X1 for a short to voltage.
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6.
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Install a 10 A fused jumper wire between the fuse output contact and B+. Verify that the front fog lamps illuminates.
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7.
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If the front fog lamps do not illuminate, test the X50A Fuse Block - Underhood signal circuit terminal 31 X1 for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate front fog lamp.
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8.
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Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block - Underhood and X5 harness connector at the K9 Body Control Module.
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9.
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Test for less than 0.3 V between the X50A Fuse Block - Underhood harness connector terminal 19 X2 and ground.
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10.
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If greater than the specified range, test the control circuit for a short to voltage.
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11.
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Test for infinite resistance between the X50A Fuse Block - Underhood harness connector terminal 19 X2 and ground.
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12.
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If less than the specified range, test the control circuit for a short to ground.
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13.
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Connect the X2 harness connector at the X50A Fuse Block - Underhood.
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14.
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Ignition ON, install a 15 A fused jumper at the K9 Body Control Module harness connector X5 and momentarily touch ground with ground with the open end. Verify the Front Fog Lamps Relay activates.
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15.
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If the Front Fog Lamps Relay is always active, test the control circuit for a short to ground. If the circuit tests normal, replace the X50A Fuse Block - Underhood.
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16.
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If the Front Fog Lamps Relay is stays inactive, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the X50A Fuse Block - Underhood.
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17.
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If all circuits test normal, replace the K9 Body Control Module.
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Front Fog Lamp Switch Malfunction
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1.
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Ignition OFF, disconnect the harness connectors X1 and X3 at the K9 Body Control Module.
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2.
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Ignition ON, test for less than 0.3 V between the 12 V reference circuit terminal 4 X3 and ground.
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3.
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If greater than the specified value, test the 12 V Reference circuit for an short to voltage.
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4.
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Test for less than 0.3 V between the signal circuit terminal 9 X1 and ground.
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5.
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If greater then the specified value, test the signal circuit for a short to voltage.
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6.
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Ignition OFF, test for infinite resistance between the signal circuit terminal 9 X1 and ground.
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7.
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If less than the specified value, test the signal circuit for a short to ground.
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8.
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Test for infinite resistance between the 12 V reference circuit terminal 4 X3 and ground.
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9.
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If less than the specified value, test the 12 V reference circuit for an short to ground.
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10.
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Press and hold the front fog lamp switch button.
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11.
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Test for 2.7-3.1 kΩ between the signal circuit terminal 9 X1 and the 12 V reference circuit terminal 4 X3.
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12.
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If not within the specified range, test the 12 V reference circuit and the signal circuit for an open/high resistance. If the circuit test normal, replace the S30 Headlamp Switch.
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Front Fog Indicator Malfunction
Ignition ON, command the instrument cluster All Indicators test ON and OFF with the scan tool. The front fog indicator lamp should be ON/OFF when changing between the commanded states.
If the front fog indicator stays always on or always off, replace the P16 Instrument Cluster.
If the front fog indicator is changing between ON and OFF, replace the K9 Body Control Module.
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
