| Diagnosis and Testing Special Tool(s) | | 73III Automotive Meter 105-R0057 or equivalent | | | Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool | | | Flex Probe Kit 105-R025C or equivalent | Principles of Operation The smart junction box (SJB) monitors the front fog lamp switch position by sending a voltage reference signal to the front fog lamp switch. When the front fog lamp switch is engaged, the voltage reference signal is routed to ground. When the low beam headlamps are on and the SJB receives an input from the front fog lamp switch indicating a request for the front fog lamps, the SJB provides ground for the fog lamp relay. When the fog lamp relay is energized, voltage is routed to the fog lamps. The SJB monitors the rear fog lamp switch by sending a voltage reference signal to the rear fog lamp switch. When the rear fog lamp switch is engaged, the voltage reference signal is routed to ground. When the SJB detects a request for the rear fog lamp, the SJB energizes an internal relay. The relay then routes voltage to the rear fog lamp. The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault is detected. A continuous diagnostic trouble code (DTC) is stored at that time for the fault. The circuit will then reset after an ignition cycle or customer demand of the function (switching the component on, 30-minute battery saver being energized). When an excessive circuit load occurs several times, the module shuts down the output until a service procedure is performed. At the same time, the continuous DTC that was stored on the first failure will not clear by a command to clear the continuous DTCs. The module will not allow this code to be cleared or the circuit restored to normal until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand DTCs present), the continuous DTC will have been cleared and the circuit function will return. Inspection and Verification - Verify the customer concern.
- Visually inspect the following for obvious signs of electrical damage.
Visual Inspection Chart | Electrical | - Battery junction box (BJB) fuse 13 (20A) (fog lamp relay)
- Smart junction box (SJB)
- Circuity
- Bulb(s)
- Fog lamp relay
- Fog lamp switch
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
NOTE:Make sure the multifunction switch is in the OFF position. NOTE:Make sure the multifunction switch is in the LOW BEAM position. -
NOTE:Make sure to use the latest scan tool software release. If the cause is not visually evident, connect the scan tool to the data link connector (DLC). -
NOTE:The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM. If the scan tool does not communicate with the VCM: - Check the VCM connection to the vehicle.
- Check the scan tool connection to the VCM.
- If the scan tool does not communicate with the vehicle:
- Verify the ignition key is in the ON position.
- Verify the scan tool operation with a known good vehicle.
- Carry out the network test:
- If the network test passes, retrieve and record the continuous memory DTCs.
- Clear the continuous DTCs and carry out the self-test diagnostics for the SJB.
- If the DTCs retrieved are related to the concern, go to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index. For all other DTCs, refer to Section 419-10 Multifunction Electronic Modules.
- If no DTCs related to the concern are retrieved, GO to Symptom Chart.
Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | The fog lamps are inoperative — front | * Fuse * Circuitry * Fog lamp relay * Fog lamp switch * Smart junction box (SJB) | * | | The fog lamp is inoperative — rear | * Fuse * Circuitry * Fog lamp switch * SJB | * | | An individual front fog lamp is inoperative | * Circuitry | * | | The fog lamps are on continuously — front | * Circuitry * Fog lamp relay * SJB | * | | The fog lamp is on continuously — rear | * Circuitry * SJB | * | Pinpoint Tests Pinpoint Test R: The Fog Lamps Are Inoperative — Front Refer to Wiring Diagrams Cell 86, for schematic and connector information. Normal Operation The smart junction box (SJB) sends a reference signal to the fog lamp switch through circuit 1347 (DB/WH). When the fog lamp switch is engaged, the voltage signal is routed to ground through circuit 570 (BK/WH). When the SJB detects the fog lamp switch has been pressed, the SJB provides a ground for the fog lamp relay coil through circuit 477 (LB/BK). When the fog lamp relay is energized, voltage is supplied through circuit 478 (TN/OG) to the fog lamps. Voltage to the fog lamp relay is provided through circuit 554 (YE/BK). Possible Causes - Fuse
- Circuit 477 (LB/BK) open
- Circuit 478 (TN/OG) open
- Circuit 554 (YE/BK) open
- Circuit 570 (BK/WH) open
- Circuit 1347 (DB/WH) open or short to ground
- Front fog lamp relay
- Front fog lamp switch
- SJB
| PINPOINT TEST A : THE FOG LAMPS ARE INOPERATIVE — FRONT | CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: USE THE RECORDED DTCS FROM THE SJB SELF-TEST | | | 1 Using the recorded results from the SJB self-test: | | | Were any DTCs recorded? Yes For DTC B2512, GO to A2. .For DTC B2030, GO to A4. .For DTC B2254, GO to A10. .For all others, REFER to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index for correct diagnostics. No | | A2: CHECK THE FOG LAMP RELAY (DTC B2512) | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Relay. | | | 3 Carry out the front fog lamp relay component test. Refer to Wiring Diagrams Cell 149, for schematic and connector information. | | | Is the front fog lamp relay OK? Yes No INSTALL a new front fog lamp relay. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation. | | A3: CHECK CIRCUIT 477 (LB/BK) FOR A SHORT TO VOLTAGE | | | 1 Disconnect SJB . | | | 2 Ignition switch in position II. | | | 3 Measure the voltage between the front fog lamp relay pin 1, circuit 477 (LB/BK), harness side and ground. | | | Is any voltage present? Yes REPAIR the circuit. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation. No | | A4: CHECK THE FRONT FOG LAMP RELAY (DTC B2030) | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Relay. | | | 3 Carry out the front fog lamp relay component test. Refer to Wiring Diagrams Cell 149, for schematic and connector information. | | | Is the front fog lamp relay OK? Yes No INSTALL a new front fog lamp relay. CLEAR the DTCs. REPEAT the self-test. | | A5: CHECK CIRCUIT 477 (LB/BK) FOR AN OPEN | | | 1 Disconnect SJB . | | | 2 Measure the resistance between the SJB C2280b-10, circuit 477 (LB/BK), harness side and the front fog lamp relay pin 1, circuit 477 (LB/BK), harness side. | | | Is the resistance less than 5 ohms? Yes No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. | | A6: CHECK CIRCUIT 554 (YE/BK) FOR AN OPEN (DTC B2030) | | | 1 Measure the voltage between the front fog lamp relay pin 2 circuit 554 (YE/BK), harness side and ground. | | | Is the voltage greater than 10 volts? Yes No VERIFY the BJB fuse 13 (20A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. | | A7: CHECK THE FRONT FOG LAMP RELAY (NO DTCS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Relay. | | | 3 Carry out the front fog lamp relay component test. Refer to Wiring Diagrams Cell 149, for schematic and connector information. | | | Is the relay OK? Yes No INSTALL a new front fog lamp relay. TEST the system for normal operation. | | A8: CHECK CIRCUIT 554 (YE/BK) FOR AN OPEN (NO DTC) | | | 1 Measure the voltage between the front fog lamp relay pin 3, circuit 554 (YE/BK), harness side and ground. | | | Is the voltage greater than 10 volts? Yes No REPAIR the circuit. TEST the system for normal operation. | | A9: CHECK CIRCUIT 478 (TN/OG) FOR AN OPEN | | | 1 Connect a fused (20A) jumper wire between the front fog lamp relay pin 3, circuit 554 (YE/BK), harness side and the front fog lamp relay pin 5, circuit 478 (TN/OG), harness side. | | | Do the fog lamps illuminate? Yes No REPAIR the circuit. TEST the system for normal operation. | | A10: CHECK CIRCUIT 1347 (DB/WH) FOR A SHORT TO GROUND | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Switch . | | | 3 Disconnect SJB . | | | 4 Measure the resistance between the front fog lamp switch C2341-6, circuit 1347 (DB/WH), harness side and ground. | | | Is the resistance greater than 10,000 ohms? Yes No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. | | A11: CHECK CIRCUIT 570 (BK/WH) FOR AN OPEN | | | 1 Measure the resistance between the front fog lamp switch C2341-2, circuit 570 (BK/WH), harness side and ground. | | | Is the resistance less than 5 ohms? Yes No REPAIR the circuit. TEST the system for normal operation. | | A12: CHECK CIRCUIT 1347 (DB/WH) FOR VOLTAGE | | | 1 Ignition switch in position II. | | | 2 Measure the voltage between the front fog lamp switch C2341-6, circuit 1347 (DB/WH), harness side and ground. | | | Is the voltage greater than 10 volts? Yes No | | A13: CHECK THE FRONT FOG LAMP SWITCH | | | 1 Ignition switch in position 0. | | | 2 Connect Front Fog Lamp Relay . | | | 3 Ignition switch in position II. | | | 4 Place the multifunction switch in the HEADLAMPS ON position. | | | 5 Connect a fused (5A) jumper wire between the front fog lamp switch C2341-6, circuit 1347 (DB/WH), harness side and the fog lamp switch C2341-2, circuit 570 (BK/WH), harness side | | | Do the fog lamps illuminate? Yes INSTALL a new front fog lamp switch. REFER to Fog Lamp Switch in this section. TEST the system for normal operation. No | | A14: CHECK CIRCUIT 1347 (DB/WH) FOR AN OPEN | | | 1 Ignition switch in position 0. | | | 2 Disconnect SJB . | | | 3 Measure the resistance between the SJB C2280e-30, circuit 1347 (DB/WH), harness side and the front fog lamp switch C2341-6, circuit 1347 (DB/WH), harness side. | | | Is the resistance less than 5 ohms? Yes No REPAIR the circuit. TEST the system for normal operation. | | A15: CHECK FOR CORRECT SJB OPERATION | | | 1 Disconnect all the SJB connectors. | | | 2 Check for: | | | 3 Connect all the SJB connectors and make sure they seat correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test S: The Fog Lamp Is Inoperative — Rear Refer to Wiring Diagrams Cell 86, for schematic and connector information. Normal Operation The smart junction box (SJB) monitors the rear fog lamp switch by sending a signal through circuit 474 (OG/LG). When the fog lamp switch is pressed, the signal is routed to circuit 570 (BK/WH). When the SJB detects a request for the rear fog lamp, the SJB sends voltage to the rear fog lamp through circuit 479 (LG/YE). The rear fog lamp is grounded through circuit 57 (BK). Possible Causes - Fuse
- Circuit 474 (OG/LG) open
- Circuit 479 (LG/YE) open
- Circuit 570 (BK/WH) open
- Circuit 57 (BK) open
- Rear fog lamp switch
- SJB
| PINPOINT TEST B : THE FOG LAMP IS INOPERATIVE — REAR | CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | B1: CHECK THE CIRCUITRY TO THE REAR FOG LAMP SWITCH | | | 1 Ignition switch in position 0. | | | 2 Disconnect SJB . | | | 3 Measure the resistance between the SJB C2280e-28, circuit 474 (OG/LG), harness side and ground while pressing and releasing the rear fog lamp switch. | | | Is the resistance less than 5 ohms with the rear fog lamp switch pressed, and greater than 10,000 ohms with the switch released? Yes No If the resistance is greater than 10,000 ohms regardless of switch position, GO to B2. .If the resistance is less than 5 ohms regardless of switch position, GO to B4. . | | B2: CHECK CIRCUIT 474 (OG/LG) FOR AN OPEN | | | 1 Disconnect Rear Fog Lamp Switch . | | | 2 Measure the resistance between the SJB C2280e-28, circuit 474 (OG/LG), harness side and the rear fog lamp switch C2343-6, circuit 474 (OG/LG), harness side and ground. | | | Is the resistance less than 5 ohms? Yes No REPAIR the circuit. TEST the system for normal operation. | | B3: CHECK CIRCUIT 570 (BK/WH) FOR AN OPEN | | | 1 Measure the resistance between the rear fog lamp switch C2343-2, circuit 570 (BK/WH), harness side and ground. | | | Is the resistance less than 5 ohms? Yes INSTALL a new rear fog lamp switch. CLEAR the DTCs. REPEAT the self-test. No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. | | B4: CHECK CIRCUIT 474 (OG/LG) FOR A SHORT TO GROUND | | | 1 Disconnect Rear Fog Lamp Switch . | | | 2 Measure the resistance between the SJB C2280e-28, circuit 474 (OG/LG), harness side and ground. | | | Is the resistance less than 5 ohms? Yes REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. No INSTALL a new rear fog lamp switch. CLEAR the DTCs. REPEAT the self-test. | | B5: CHECK CIRCUIT 57 (BK) FOR AN OPEN | | | 1 Disconnect Rear Fog Lamp . | | | 2 Measure the resistance between the rear fog lamp C451-3, circuit 57 (BK), harness side and ground. | | | Is the resistance less than 5 ohms? Yes VERIFY the SJB fuse 8 (15A) is OK. If OK, GO to B6. . No REPAIR the circuit. TEST the system for normal operation. | | B6: CHECK CIRCUIT 479 (LG/YE) FOR AN OPEN | | | 1 Disconnect SJB . | | | 2 Measure the resistance between the SJB C2280d-14, circuit 479 (LG/YE), harness side and the rear fog lamp C451-1, circuit 479 (LG/YE), harness side and ground. | | | Is the resistance less than 5 ohms? Yes No REPAIR the circuit. TEST the system for normal operation. | | B7: CHECK FOR CORRECT SJB OPERATION | | | 1 Disconnect all the SJB connectors. | | | 2 Check for: | | | 3 Connect all the SJB connectors and make sure they seat correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test T: An Individual Front Fog Lamp Is Inoperative Refer to Wiring Diagrams Cell 86, for schematic and connector information. Normal Operation When the fog lamp relay is energized, voltage is supplied through circuit 478 (TN/OG) to the fog lamps. Ground for the fog lamps is provided through circuit 57 (BK). Possible Causes - Circuit 57 (BK) open
- Circuit 478 (TN/OG) open
| PINPOINT TEST C : AN INDIVIDUAL FRONT FOG LAMP IS INOPERATIVE | CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | C1: CHECK THE FOG LAMP GROUND CIRCUIT | | | 1 Ignition switch in position 0. | | | 2 Disconnect Inoperative Front Fog Lamp. | | | 3 Measure the resistance between the LH fog lamp C152-2, circuit 57 (BK), harness side and ground; or between the RH fog lamp C162-2, circuit 57 (BK), harness side and ground. | | | Is the resistance less than 5 ohms? Yes REPAIR circuit 478 (TN/OG) for an open. TEST the system for normal operation. No REPAIR circuit 57 (BK) for an open. TEST the system for normal operation. | Pinpoint Test U: The Fog Lamps Are On Continuously — Front Refer to Wiring Diagrams Cell 86, for schematic and connector information. Normal Operation The smart junction box (SJB) sends a reference signal to the fog lamp switch through circuit 1347 (DB/WH). When the fog lamp switch is engaged, the voltage signal is routed to ground through circuit 570 (BK/WH). When the SJB detects the fog lamp switch has been pressed, the SJB provides a ground for the fog lamp relay coil through circuit 477 (LB/BK). When the fog lamp relay is energized, voltage is supplied through circuit 478 (TN/OG) to the fog lamps. Possible Causes - Circuit 477 (LB/BK) short to ground
- Circuit 478 (TN/OG) short to voltage
- Front fog lamp relay
- SJB
| PINPOINT TEST D : THE FOG LAMPS ARE ON CONTINUOUSLY — FRONT | CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | D1: USE THE RECORDED DTCS FROM THE SJB SELF-TEST | | | 1 Check for recorded results from the SJB self-test. | | | Were any DTCs recorded? Yes For DTC B2030, GO to D2. .For all others, REFER to the Smart Junction Box Diagnostic (SJB) Trouble Code (DTC) Index for correct diagnostics. No | | D2: CHECK CIRCUIT 477 (LB/BK) FOR A SHORT TO GROUND | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Relay . | | | 3 Disconnect SJB . | | | 4 Measure the resistance between the front fog lamp relay pin 1, circuit 477 (LB/BK), harness side and ground. | | | Is the resistance greater than 10,000 ohms? Yes No REPAIR the circuit. TEST the system for normal operation. | | D3: CHECK CIRCUIT 478 (TN/OG) FOR A SHORT TO VOLTAGE | | | 1 Ignition switch in position 0. | | | 2 Disconnect Front Fog Lamp Relay . | | | 3 Ignition switch in position II. | | | Do the fog lamps continue to illuminate? Yes REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. No INSTALL a new front fog lamp relay. CLEAR the DTCs. REPEAT the self-test. | | D4: CHECK FOR CORRECT SJB OPERATION | | | 1 Disconnect all the SJB connectors. | | | 2 Check for: | | | 3 Connect all the SJB connectors and make sure they seat correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test V: The Fog Lamp Is On Continuously — Rear Refer to Wiring Diagrams Cell 86, for schematic and connector information. Normal Operation The smart junction box (SJB) monitors the rear fog lamp switch by sending a signal through circuit 474 (OG/LG). When the fog lamp switch is pressed, the signal is routed to circuit 570 (BK/WH). When the SJB detects a request for the rear fog lamp, the SJB sends voltage to the rear fog lamp through circuit 479 (LG/YE). Possible Causes - Circuit 479 (LG/YE) short to voltage
- SJB
| PINPOINT TEST E : THE FOG LAMP IS ON CONTINUOUSLY — REAR | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | E1: CHECK CIRCUIT 479 (LG/YE) FOR A SHORT TO VOLTAGE | | | 1 Ignition switch in position 0. | | | 2 Disconnect SJB . | | | 3 Ignition switch in position II. | | | 4 Observe the rear fog lamp. | | | Does the rear fog lamp continue to illuminate? Yes REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. No | | E2: CHECK FOR CORRECT SJB OPERATION | | | 1 Disconnect all the SJB connectors. | | | 2 Check for: | | | 3 Connect all the SJB connectors and make sure they seat correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | |
