| Diagnosis and Testing Refer to Wiring Diagrams Section 417-01, for schematic and connector information. Special Tool(s) | | Terminal Probe Kit 29-011A | Inspection and Checking - Verify the customer concern.
- Visually check the following electrical causes for the concern:
Visual Inspection | Electrical | - Fuse(s)
- Bulb(s)
- Connectors
- Trailer socket
- Trailer lamps
- Wiring harness
| - Resolve any obvious causes or concerns found during the visual inspection before carrying out any further tests.
- If the concern persists, check the symptoms and continue with the symptom chart.
Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | Trailer lamps inoperative | * Circuit(s) in vehicle * Circuit(s) in trailer * Trailer socket * Rear fog lamp cut-off relay | * | | One individual trailer lamp inoperative | * Circuit(s) in vehicle * Circuit(s) in trailer | * | | Trailer lamps illuminate continuously | * Circuit(s) in vehicle * Circuit(s) in trailer * Trailer socket * Generic electronic module (GEM) | * | System Checks NOTE:Use a digital multimeter for all electrical measurements. | PINPOINT TEST A : TRAILER LAMPS INOPERATIVE | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: DETERMINE WHICH LAMPS ON THE TRAILER ARE INOPERATIVE | | | 1 Ignition switch in position II. | | | 2 Switch on the SIDE LIGHTS, STOP LAMPS, REAR FOG LAMPS and LEFT and RIGHT-HAND TURN SIGNAL LAMPS in turn. Engage REVERSE GEAR. | | | 3 Check the trailer lamps. | | | Are all lamps on the trailer inoperative? Yes No Only rear fog lamp(s) inoperative: GO to A3. | | A2: CHECK THE GROUND CONNECTION OF THE TRAILER SOCKET | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between: - 7-pin auxiliary trailer socket C1043, pin 3, circuit (BN/WH) and ground.
- 7-pin trailer socket, C1042, pin 3, circuit (BN) and ground.
- 13-pin trailer socket, C1058, pin 3, circuit (BN) and ground and between pin 13, circuit (BN/WH) and ground.
| | | Is the resistance less than 2 Ohm? Yes Continue fault finding on the trailer. No LOCATE and RECTIFY the break in the circuit between the trailer socket and ground G3 using the Wiring Diagrams. CHECK the operation of the system. | | A3: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE REAR FOGLAMPS SWITCHED ON | | | 1 Ignition switch in position II. | | | 2 SWITCH ON the rear fog lamp. | | | 3 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 2, circuit (RD/YE) and ground. | | | Does the meter display battery voltage? Yes Continue fault finding on the trailer. No - LHD without rear fog lamp cut-off relay, except Courier: LOCATE and RECTIFY the break in the circuit between intermediate connector C1053 (RD/YE) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | A4: CHECK THE REAR FOG LAMP CUT-OFF RELAY | NOTE:The rear fog lamp is still switched on. | | | 1 Ignition switch in position 0. | | | 2 Disconnect rear fog lamp cut-off relay from socket C1040. | | | 3 Use a fused test cable (10 A) at the rear fog lamp cut-off relay to bridge between socket C1040, circuit (RD/WH) and (RD/YE), wiring harness side. | | | 4 Ignition switch in position II. | | | 5 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 2, circuit (RD/YE) and ground. | | | Does the meter display battery voltage? Yes - RHD with additional trailer socket, except Courier: RENEW the rear fog lamp cut-off relay CHECK the operation of the system. No LOCATE and RECTIFY the break in the circuit between the rear fog lamp cut-off relay and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | A5: CHECK THE GROUND CONNECTION OF THE REAR FOG LAMP CUT-OFF RELAY | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between the rear fog lamp cut-off relay, socket C1040, circuit (BN), wiring harness side and ground. | | | Is the resistance less than 2 Ohm? Yes RENEW the rear fog lamp cut-off relay CHECK the operation of the system. No LOCATE and RECTIFY the break in the circuit between the rear fog lamp cut-off relay and ground G3 using the Wiring Diagrams. CHECK the operation of the system. | | PINPOINT TEST B : ONE INDIVIDUAL TRAILER LAMP INOPERATIVE | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | B1: DETERMINE WHICH LAMP IS INOPERATIVE | | | 1 Ignition switch in position II. | | | 2 Check the trailer lamps. | | | Is one of the rear lamps on the trailer inoperative? Yes - Left-hand trailer rear lamp inoperative: GO to B2. - Right-hand trailer rear lamp inoperative: GO to B3. No - Left-hand trailer turn signal lamp inoperative: GO to B4. - Right-hand trailer turn signal lamp inoperative: GO to B5. - Trailer stop lamps inoperative: GO to B6. - Trailer reversing lamp(s) inoperative: GO to B7. - Trailer rear fog lamp(s) inoperative: GO to Pinpoint Test A. | | B2: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE SIDE LIGHTS SWITCHED ON | | | 1 SWITCH ON the side lights. | | | 2 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 7, circuit (GY/BK) and ground. | | | Does the meter display battery voltage? Yes Continue fault finding on the trailer. No LOCATE AND RECTIFY the break in the circuit between intermediate connector C50, pin 3, or C1050, pin 4, (Courier, refrigerated van) circuit (GY/BK) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | B3: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE SIDE LIGHTS SWITCHED ON | | | 1 SWITCH ON the side lights. | | | 2 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 5, circuit (GY/RD) and ground. | | | Does the meter display battery voltage? Yes Continue fault finding on the trailer. No LOCATE AND RECTIFY the break in the circuit between intermediate connector C49, pin 3, or C1049, pin 4, (Courier, refrigerated van) circuit (GY/RD) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | B4: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE LEFT-HAND TURN SIGNAL SWITCHED ON | | | 1 Ignition switch in position II. | | | 2 SWITCH ON the left-hand turn signal. | | | 3 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 1, circuit (BK/WH) and ground. | | | Does the voltage alternate between 0 V and battery voltage? Yes Continue fault finding on the trailer. No LOCATE AND RECTIFY the break in the circuit between intermediate connector C50, pin 1, or C1050, pin 5, (Courier, refrigerated van) circuit (BK/WH) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | B5: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE RIGHT-HAND TURN SIGNAL SWITCHED ON | | | 1 Ignition switch in position II. | | | 2 SWITCH ON the right-hand turn signal. | | | 3 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 4, circuit (BK/GN) and ground. | | | Does the voltage alternate between 0 V and battery voltage? Yes Continue fault finding on the trailer. No LOCATE AND RECTIFY the break in the circuit between intermediate connector C49, pin 5, or C1049, pin 5, (Courier, refrigerated van) circuit (BK/WH) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | B6: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH THE BRAKES APPLIED | | | 1 Ignition switch in position II. | | | 2 APPLY the brakes. | | | 3 Measure the voltage between the trailer socket C1042 (7-pin socket) or C1058 (13-pin socket), pin 6, circuit (BK/RD) and ground. | | | Does the meter display battery voltage? Yes Continue fault finding on the trailer. No LOCATE AND RECTIFY the break in the circuit between intermediate connector C50, pin 2, or C1050, pin 3, (Courier, refrigerated van) circuit (BK/RD) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | B7: CHECK THE VOLTAGE AT THE TRAILER SOCKET WITH REVERSE GEAR ENGAGED | | | 1 Ignition switch in position II. | | | 2 ENGAGE reverse gear. | | | 3 Measure the voltage between the trailer socket C1043 (7-pin additional trailer socket), pin 1 or C1058 (13-pin socket), pin 8, circuit (BK) and ground. | | | Does the meter display battery voltage? Yes Continue fault finding on the trailer. No - RHD, vehicles with additional trailer socket: LOCATE and RECTIFY the break in the circuit between intermediate connector C50, pin 5, circuit (BK) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. - LHD with 13-pin trailer connector, LOCATE and RECTIFY the break in the circuit between intermediate connector C49, pin 1, circuit (BK) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. - Courier, refrigerated van, LOCATE and RECTIFY the break in the circuit between intermediate connector C1050, pin 6, circuit (BK) and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. | | PINPOINT TEST C : TRAILER LAMPS ILLUMINATE CONTINUOUSLY | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | C1: CHECK THE FAULT SYMPTOMS | | | 1 Ignition switch in position II. | | | 2 Check the trailer lamps. | | | Does/do the trailer rear fog lamp(s) illuminate continuously? Yes - LHD without rear fog lamp cut-off relay, except Courier: GO to C2. No - Trailer rear lamps illuminate continuously: GO to C5. - Trailer stop lamps illuminate continuously: GO to C8. - Trailer reversing lamps illuminate continuously (Courier, refrigerated van): GO to C11. - Trailer reversing lamps illuminate continuously (all others): GO to C9. - Trailer turn signal lamp(s) illuminate(s) continuously: GO to C12. | | C2: CHECK FOR SHORT TO BATTERY VOLTAGE AT THE TRAILER SOCKET (REAR FOG LAMP) | | | 1 Measure the voltage between the trailer socket C1042 (7-pin socket), pin 2, circuit (RD/YE) and ground. | | | Does the meter display battery voltage? Yes No Continue fault finding on the trailer. | | C3: CHECK GEM MODULE | | | 1 Ignition switch in position 0. | | | 2 Disconnect fuse F3 (CJB). | | | 3 Disconnect fuse F8 (CJB). | | | 4 Disconnect fuse F12 (CJB). | | | 5 Disconnect fuse F18 (CJB). | | | 6 Ignition switch in position II. | | | 7 Measure the voltage between the trailer socket C1042 (7-pin socket), pin 2, circuit (RD/YE) and ground. | | | Does the meter display battery voltage? Yes LOCATE and RECTIFY the short to battery voltage in the circuits connected to the connector C212b, pin 6 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. No RENEW the GEM module. CHECK the operation of the system. | | C4: CHECK FOR SHORT TO BATTERY VOLTAGE AT THE TRAILER SOCKET (REAR FOG LAMP) | | | 1 Measure the voltage between the trailer socket C1042 (7-pin socket), pin 2, or C1058 (13-pin socket), pin 2, circuit (RD/YE) and ground. | | | Does the meter display battery voltage? Yes LOCATE and RECTIFY the short to battery voltage in the circuit between the rear fog lamp cut-off relay and the trailer socket using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. No Continue fault finding on the trailer. | | C5: DETERMINE THE FAULT CONDITION | | | 1 Ignition switch in position 0. | | | 2 Disconnect fuse F6 (CJB). | | | 3 Disconnect fuse F7 (CJB). | | | 4 Ignition switch in position II. | | | 5 CHECK parking lamps, rear lamps and license plate lamps. | | | Are the left-hand parking lamps illuminated continuously? Yes The left-hand parking lamps illuminate continuously: GO to C6. No The right-hand parking lamps illuminate continuously: GO to C7. | | C6: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE (LEFT-HAND REAR LAMP) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - Courier, refrigerated van: C1050
| | | 3 Ignition switch in position II. | | | Does the left-hand side light illuminate continuously? Yes The left-hand front side light illuminates continuously: REFER to Section 417-01 Exterior Lighting.- Parking lamps, rear lamps, license plate lamps. No - The left-hand rear lamp illuminates continuously. LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C50, pin 3 or C1050, pin 4 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | | C7: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE (RIGHT-HAND REAR LAMP) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - Courier, refrigerated van C1049
| | | 3 Ignition switch in position II. | | | Does the right-hand side light illuminate continuously? Yes The right-hand front side light illuminates continuously: REFER to Section 417-01 Exterior Lighting.- Parking lamps, rear lamps, license plate lamps. No - The right-hand rear lamp illuminates continuously. LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C49, pin 3 or C1049, pin 4 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | | C8: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE (STOP LAMPS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - Courier, refrigerated van: C1050
| | | 3 Ignition switch in position II. | | | Do the stop lamps illuminate continuously? Yes No - The left-hand stop lamps illuminate continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C50, pin 2 or C1050, pin 3 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | | C9: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE (REVERSING LAMPS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - RHD: C50 (with 7-pin additional trailer socket)
- LHD: C49 (with 13-pin additional trailer socket)
| | | 3 Ignition switch in position II. | | | Does the left-hand (RHD) or right-hand (LHD) reversing lamp illuminate continuously: Yes - RHD: The left-hand reversing lamp illuminates continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C50, pin 5 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - LHD: The right-hand reversing lamp illuminates continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C49, pin 1 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. No | | C10: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE | | | 1 Measure the voltage at intermediate connector C50, pin 5, (RHD) or C49, pin 1, (LHD), circuit 14S-LG39 (VT/OG) and ground. | | | Does the meter display battery voltage? Yes No No faulty operation can be found: Continue fault finding on the trailer. | | C11: NARROW DOWN THE LOCATION OF THE SHORT TO BATTERY VOLTAGE ON THE VEHICLE (REVERSING LAMPS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector C1050. | | | 3 Ignition switch in position II. | | | Do the reversing lamps illuminate continuously? Yes No - The left-hand reversing lamp illuminates continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C1050, pin 6 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | | C12: DETERMINE THE FAULT CONDITION | | | 1 CHECK the turn signal lamps. | | | Do the left-hand turn signal lamps illuminate continuously? Yes Left-hand turn signal lamps illuminate continuously: GO to C13. No - Right-hand turn signal lamps illuminate continuously: GO to C14. - Both sides illuminate continuously: REFER to Section 417-01 Exterior Lighting.- Turn signal lamps/hazard warning lamps. | | C13: CHECK FOR SHORT TO BATTERY VOLTAGE ON THE VEHICLE (LEFT-HAND TURN SIGNAL LAMPS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - Courier, refrigerated van: C1050
| | | 3 Ignition switch in position II. | | | Do the left-hand turn signal lamps illuminate continuously? Yes The left-hand front turn signal lamp illuminates continuously: REFER to Section 417-01 Exterior Lighting.- Turn signal lamps/hazard warning lamps. No - The left-hand rear turn signal lamp illuminates continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C50, pin 1 or C1050, pin 5 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | | C14: CHECK FOR SHORT TO BATTERY VOLTAGE ON THE VEHICLE (RIGHT-HAND TURN SIGNAL LAMPS) | | | 1 Ignition switch in position 0. | | | 2 Disconnect intermediate connector. - Courier, refrigerated van: C1049
| | | 3 Ignition switch in position II. | | | Do the right-hand turn signals illuminate continuously? Yes The right-hand front turn signal lamp illuminates continuously: REFER to Section 417-01 Exterior Lighting.- Turn signal lamps/hazard warning lamps. No - The right-hand rear turn signal lamp illuminates continuously: LOCATE and RECTIFY the short to battery voltage in the circuits connected to intermediate connector C49, pin 5 or C1049, pin 5 using the Wiring Diagrams. CHECK the operation of the system. If necessary RENEW the trailer socket. CHECK the operation of the system. - No malfunction detected: Continue fault finding on the trailer. | |
