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Body Control Module: Diagnosis GMC Envoy I

Body, Cab Control Systems ~14381 words

SELF-DIAGNOSTIC SYSTEM

Note. Use of scan tool is required for reading DTC(s). TBC module does not turn on SERVICE ENGINE SOON MIL. It will turn on the SECURITY indicator light for PassLock(R) system related malfunctions.

Truck Body Control (TBC) module is equipped with a self-diagnostic system, which detects system Diagnostic Trouble Codes (DTCs) or abnormalities. When a malfunction occurs, TBC will store a DTC. See TBC MODULE DTC DEFINITIONS . Malfunctions are recorded as history/intermittent failures or as current failures.

Current DTCs indicate TBC module has detected a fault which is currently present. A history DTC indicates that TBC module has previously detected a malfunction that is not currently present.

A scan tool must be used to retrieve and clear DTCs. The scan tool also has several features that can be used to help locate an intermittent condition.

TBC MODULE DTC DEFINITIONS

DTCCircuit Affected
B13975-Volt Reference Circuit Low
B13985-Volt Reference Circuit High
B1477RAP Circuit Low
B1478RAP Circuit High
B1480Inadvertent Power Circuit Malfunction
B2527Front Foglight Circuit Low
B2537Rear Foglight Circuit Low (Export Only)
B2575Headlight Request/Feedback Mismatch
B2577Headlight Control Circuit Low
B2585Park Light Control Circuit Malfunction
B2600Daytime Running Light Circuit Malfunction
B2613Dimming Potentiometer Circuit High
B2617Courtesy Light Circuit Low
B2618Courtesy Light Circuit High
B2647Ambient Light Sensor Circuit Low
B2648Ambient Light Sensor Circuit High
B2752Horn Relay Coil Circuit Low
B2947 (1)Security System Sensor Power Circuit Low
B2948 (1)Security System Sensor Power Circuit High
B2957 (1)Security System Sensor Circuit Low
B2958 (1)Security System Sensor Circuit High
B2960 (1)Security System Sensor Data Incorrect But Valid
B2961Ignition 1 - Key In/Out Mismatch
B3031 (1)Security System Controller In Learn Mode
B3033 (1)Security System Indicates Tamper
B3102Keyless Entry (RFA) Data Link Circuit Low
B3137Door Lock Circuit Low
B3138Door Lock Circuit High
B3147Passenger Door Unlock Circuit Low
B3148Passenger Door Unlock Circuit High
U1255Class 2 Communication Malfunction
U1301Class 2 Data Link High
(1) See ANTI-THEFT SYSTEM article.
(1)See ANTI-THEFT SYSTEM article.

TBC MODULE DTC DEFINITIONS

DIAGNOSIS & TESTING

Note. For wiring and connector terminal identification, see WIRING DIAGRAMS .

Note. When testing procedure indicates to probe or check a terminal, use adapters from connector Test Adapter Kit (J-35616-A). This will ensure terminal will not be damaged, and that connection is okay.

Note. Only disconnect specified BCM/TBC module connector. If all BCM/TBC module connectors need to be disconnected, they need to be disconnected in a specific order, or BCM/TBC related DTCs will set. See TRUCK BODY CONTROL (TBC) MODULE under REMOVAL & INSTALLATION.

TBC MODULE DIAGNOSTIC SYSTEM CHECK

Note. Use of Tech 2 scan tool is recommended. Follow scan tool manufacturer's instructions.

Note. Use this check as the starting point for any TBC module complaint. Most malfunctions are caused by faulty wiring, connectors or components.

Diagnostic Procedures

  1. Turn ignition off. Connect scan tool. Turn ignition switch to RUN position, but DO NOT start engine. Using scan tool, attempt to establish communication with TBC module. If scan tool communicates with TBC module, go to next step. If scan tool does not communicate with TBC module, go to step 3).
  2. Using scan tool, check for TBC module related DTCs. If any DTC exists, go to appropriate DTC test. If no DTCs exist, system is operating properly.
  3. Attempt to establish communication with other systems connected to same serial data line (VCM, IPC, HVAC, etc.). If scan tool communicates with other systems, go to next step. If scan tool does not communicate with other systems, go to «SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 SERIAL DATA LINE»(ref-33327-S16256412692001101600000) .
  4. Ensure ignition switch is in RUN position, with engine off. Using a test light connected to ground, probe both sides of TBC power feed fuse. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If test light does not illuminate on all circuits, go to step 9). If test light illuminates on all circuits, go to next step. NOTE: Disconnect module harness connectors in specific order, or BCM/TBC related DTCs will set.
  5. Turn ignition off. Disconnect TBC module harness connectors C1, C2 and C3. Turn ignition switch to RUN position. Using a test light connected to ground, probe both side of all TBC module power feed fuses. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . Probe Brown TBC module harness connector power feed terminals. If test light does not illuminate on all circuits, go to step 11). If test light illuminates on all circuits, go to next step.
  6. Using a test light connected to battery voltage, probe each TBC module ground circuit. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If test light illuminates at all circuits, go to next step. If test light does not illuminate at all circuits, go to step 12).
  7. Using DVOM, check for continuity between TBC module harness connector C1 terminal A12 (Light Green wire) and Data Link Connector (DLC) terminal No. 2 (Purple wire). If continuity is present, go to next step. If continuity is not present, go to step 10).
  8. Replace TBC module. Reprogram TBC module. See procedures in «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After repairs, go to step 13).
  9. Repair open in ignition or battery feed to TBC module power feed fuse. If any fuse is open, locate and repair short in affected circuit. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . After repairs, go to step 13).
  10. Locate and repair open in Light Green or Purple wire between TBC module harness connector C1 and DLC. After repairs, go to step 13).
  11. Locate and repair open in TBC module power circuit. After repairs, go to step 13).
  12. Locate and repair open in TBC module ground circuit. After repairs, go to next step.
  13. Turn ignition off. Reinstall all components or connectors. Clear DTCs. See «CLEARING DTCS»(ref-33327-S08500004602001101600000) . After clearing DTCs, ensure system is operating properly. If DTCs are set, go to appropriate DTC diagnostic test.

SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 SERIAL DATA LINE

Note. To identify wire colors and modules on Class-II serial data line, see WIRING DIAGRAMS .

  1. Turn ignition off. Install scan tool. Turn ignition on, with engine off. If scan tool powers up, go to step 9). If scan tool does not power up, go to next step.
  2. Disconnect scan tool from DLC. Check for proper connection of scan tool to DLC terminals No. 4 (Black wire) and 16 (Orange wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If connections are okay, go to next step. If connections are faulty, go to step 7).
  3. Using DVOM, check voltage between ground and DLC terminal No. 16 (Orange wire). If voltage reading is about 12 volts, go to next step. If voltage reading is not about 12 volts, go to step 7).
  4. Using DVOM, check resistance between ground and DLC terminal No. 4 (Black wire). If resistance is 0-5 ohms, go to step 6). If resistance is not 0-5 ohms, go to step 8).
  5. Repair connections as necessary. After repairs, recheck system operation.
  6. Check scan tool for malfunction. Use a known-good scan tool and go to step 1).
  7. Repair open in Orange wire between DLC and instrument panel fuse block. After repairs, recheck system operation.
  8. Repair open in Black wire between DLC and ground connector. After repairs, recheck system operation.
  9. Turn ignition switch to RUN position. Using scan tool, attempt to establish communication with each module on the class 2 data link. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If all modules are communicating, go to next step. If not all modules are communicating, go to step 13).
  10. If DTCs U1000 or U1xxx (Lost Communication With xxx Module) is set, go to next step. If other than a "U" type code/DTC(s) is set, go to step 12).
  11. Diagnose affected DTCs. See «TBC MODULE DTC DEFINITIONS»(ref-33327-S11763703652001101600000) table. After diagnosing DTC(s), recheck system operation.
  12. Diagnose affected DTC(s). After diagnosing DTC(s), recheck system operation.
  13. Turn ignition off. Check scan tool for proper connection at DLC terminal No. 5 (Black/White wire). If connection is okay, go to step 14). If connection is faulty, go to step 5).
  14. Using DVOM, check resistance between ground and DLC terminal No. 5 (Black/White wire). If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step 30).
  15. Check scan tool for proper connection at DLC terminal No. 2 (Purple wire). If connection is okay, go to next step. If connection is faulty, go to step 5).
  16. Disconnect splice connector SP201 (located between DLC and left side of instrument panel, below fuse block). Check for proper connection of Class-II serial data circuit and terminal "A" (Purple wire) of splice connector. If connection is okay, go to next step. If connection is faulty, go to step 5).
  17. Check resistance between DLC terminal No. 2 (Purple wire) and splice connector SP201 terminal "A" (Purple sire). If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step 29).
  18. Check resistance between DLC terminals No. 2 (Purple wire) and No. 4 (Black wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 28).
  19. Turn ignition switch to RUN position. Check voltage between DLC terminals No. 2 (Purple wire) and No. 4 (Black wire). If voltage reading is 0-1 volt, go to next step. If voltage reading is not 0-1 volt, go to step 27).
  20. Turn ignition off. Using Terminal Adapter Kit (J356516-A), connect appropriate terminal adapter to splice pack SP201. Connect a jumper wire between splice pack terminal "A" and to terminal connected to affected module in splice pack. Turn ignition switch to RUN position. Using scan tool, attempt to establish communication with module which is jumpered to DLC. If communication can be established, go to next step. If communication cannot be established, go to step 22).
  21. Repeat step 20) for each module on Class-II serial data link. If communication can be established for each module, go to step 31). If communication cannot be established for each module, go to next step.
  22. Turn ignition off. Disconnect module which does not communicate. Check resistance from splice pack SP201 terminal to Class-II serial data circuit for the disconnected module to ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 28).
  23. Turn ignition switch to RUN position. Check voltage from class 2 serial data circuit of the disconnected module to ground. If voltage reading is 0-1 volt, go to next step. If voltage reading is not 0-1 volt, go to step 27).
  24. Turn ignition off. Inspect connector of disconnected module in the area of the Class-II serial data circuit for backed out terminals, causing a short to ground or voltage. If all terminals are properly locked into connector body, go to next step. If terminals are not properly locked into connector body, go to step 5).
  25. Replace module that does not communicate. Reconnect splice pack SP201. Reconnect all modules on Class-II serial data link. Turn ignition switch to RUN position. Using scan tool, attempt to establish communication with module that was replaced. If communication can be established, go to step 31). If communication cannot be established, go to next step.
  26. Replace class 2 serial data circuit wire between splice pack SP201 and module that does not communicate. After repairs, go to step 31).
  27. Turn ignition off. Repair short to voltage in Class-II serial data circuit. After repairs, go to step 31).
  28. Repair short to ground in class 2 serial data circuit. After repairs, go to step 31).
  29. Repair open in class 2 serial data circuit. After repairs, recheck system operation.
  30. Repair open in Black/White wire between DLC and BBEC. After repairs, recheck system operation.
  31. Reconnect splice connector SP201 and all modules on the class 2 serial data link. Turn ignition switch to RUN position. Wait 10 seconds. Check for DTCs in each module on the class 2 serial data link. If any current "U" codes/DTCs are present, go to step 33). If no current "U" codes/DTCs are present, go to next step.
  32. If other DTCs are set (not "U" code), go to next step. If "U" codes/DTCs are set, go to step 34).
  33. Diagnose DTC(s) set. Go to appropriate DTC diagnosis. After diagnosing DTC(s) go to step 35).
  34. Diagnose DTCs. After diagnosing DTC(s), go to next step.
  35. Clear all DTCs. After clearing DTCs, recheck system operation.

Circuit Description

The ambient light sensor is an input to the TBC module. TBC module uses the light sensor input to determine the level of light to turn headlights on or off automatically. TBC module monitors the 5-volt reference circuit to light sensor. When TBC module does not see 5 volts on this circuit, DTC will set. TBC also monitors ignition switch position based on ignition signal inputs. TBC performs a self-test on power up.

Conditions for setting DTC

  1. Light sensor circuit(s) shorted to ground.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step. NOTE: Ensure DTC B1397 is a current code before proceeding with test.
  2. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If voltage reading is 4.75-5.25 volts, DTC is intermittent. See DIAGNOSTIC AIDS. If voltage is not 4.75-5.25 volts, go to next step.
  3. Turn ignition off. Disconnect Purple TBC module harness connector. Check for good connection at harness connector terminal A4 (Gray wire). If connection is okay, go to next step. If connection is faulty, go to step 7).
  4. Reconnect Purple TBC module harness connector. Using scan tool, clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B1397 is set as current code. If code is current, go to next step. If code is not current, go to step 8).
  5. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If circuit is shorted to ground, go to step 8). If circuit is not shorted, go to next step.
  6. Replace TBC module. Program and perform TCM module relearn procedure. See «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and TBC/BCM RELEARN PROCEDURE. After programming TBC module, go to step 13).
  7. Repair terminal connection. After repairs, go to step 13).
  8. Disconnect light sensor harness connector. Turn ignition off. Using DVOM, check for short to ground or open in light sensor Gray wire circuit between sensor and TBC module. If circuit is shorted or open, go to step 10). If circuit is okay, go to step 11).
  9. Replace light sensor. After replacing sensor, go to step 13).
  10. Repair Gray wire circuit. After repairs, go to step 13).
  11. Check for short to ground in White wire between TBC module and light sensor. If circuit is shorted, go to next step. If circuit is okay, go to step 9).
  12. Repair White wire circuit. After repairs, go to next step.
  13. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Diagnostic Aids

Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. If reference voltage is greater than 5.25 volts, perform DTC B1398 diagnostics first. Perform visual checks of wiring and harness connectors for intermittent and poor connections.

The ambient light sensor is an input to the TBC module. TBC module uses the light sensor input to determine the level of light to turn headlights on or off automatically. TBC module monitors the 5-volt reference circuit to light sensor. When TBC module does not see 5 volts on this circuit, DTC will set. TBC also monitors ignition switch position based on ignition signal inputs. TBC performs a self-test on power up.

Conditions for setting DTC

  1. Light sensor circuit(s) shorted to battery voltage.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step. NOTE: Ensure DTC B1398 is a current code before proceeding with test.
  2. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If voltage reading is not greater than 5.25 volts, DTC is intermittent. See DIAGNOSTIC AIDS. If voltage is greater than 5.25 volts, go to next step.
  3. Turn ignition off. Disconnect Purple TBC module harness connector. Check for good connection at harness connector terminal A4 (Gray wire). If connection is okay, go to next step. If connection is faulty, go to step 7).
  4. Reconnect Purple TBC module harness connector. Using scan tool, clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1398 is set as current code, go to next step. If DTC B1398 is not set as a current code, go to step 8).
  5. Turn ignition switch to RUN position. Using DVOM connected to ground, backprobe Purple TBC module harness connector terminal A4 (Gray wire). If voltage reading is 5.25 volts or greater, go to step 8). If voltage reading is not 5.25 volts or greater, go to next step.
  6. Replace TBC module. Program and perform TCM module relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming TBC module, go to step 13).
  7. Repair terminal connection. After repairs, go to step 13).
  8. Disconnect light sensor harness connector. Turn ignition off. Using DVOM, check for short to voltage in light sensor Gray wire circuit between sensor and TBC module. If circuit is shorted to voltage, go to step 10). If circuit is okay, go to step 11).
  9. Replace light sensor. After replacing sensor, go to step 13).
  10. Repair Gray wire circuit. After repairs, go to step 13).
  11. Check for short to voltage in White wire between TBC module and light sensor. If circuit is shorted, go to next step. If circuit is okay, go to step 9).
  12. Repair White wire circuit. After repairs, go to next step.
  13. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Light sensor values on scan tool should change when light sensor is disconnected. Perform visual checks of wiring and harness connectors for intermittent and poor connections.

TBC module monitors voltage on circuit No. 755 (Black wire) between TBC module and BBEC. If TBC module does not command the RAP relay on and ignition is in off with door open, and voltage on circuit is low, DTC will set. TBC module uses this circuit to turn on RAP relay. TBC also monitors the ignition switch position based on ignition signal inputs. TBC module performs a self-test on power up.

Conditions for setting DTC

  1. Retained Accessory Power (RAP) relay signal from TBC remains low with ignition off and door open.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Check RAP MaxiFuse(R) (located in underhood electrical center). If fuse is okay, go to next step. If fuse is open, go to step 6).
  3. Turn ignition off and remove key from ignition. Open door (RAP off). Disconnect Brown TBC module harness connector. Remove RAP relay (located in BBEC). Using DVOM, check resistance between ground and Brown TBC module harness connector terminal A7 (Black wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If reading is infinite, go to next step. If reading is not infinite, go to step 7).
  4. Reconnect all components. Clear DTCs. Turn ignition off. Open, then close both doors. Turn ignition switch to RUN position. Check DTCs. If DTC B1477 is set as current code, go to next step. If DTC B1477 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  5. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 10).
  6. Ensure Red wire (circuit No. 542) between underhood electrical center and BBEC is not shorted to ground. Repair as necessary. Replace fuse. After repairs, go to step 10).
  7. Disconnect BBEC harness connector. Check resistance between ground and Brown TBC module harness connector terminal A7 (Black wire). If reading is infinite, go to next step. If reading is not infinite, go to step 9).
  8. Replace BBEC. After repairs, go to step 10).
  9. Repair short to ground in Black wire. After repairs, go to next step.
  10. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring and harness connectors for intermittent and poor connections.

TBC module monitors voltage on circuit No. 755 (Black wire) between TBC module and BBEC. If TBC module does not command the RAP relay on and ignition switch is in RUN position, then turned off with door closed, and voltage on circuit is high, DTC will set. TBC module uses this circuit to turn on RAP relay. TBC also monitors the ignition switch position based on ignition signal inputs. TBC module performs a self-test on power up.

Conditions for setting DTC

  1. RAP relay signal from TBC remains high.
  2. Ignition switch is turned from RUN to OFF position with door closed.
  3. System voltage 9-16 volts.
  4. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off and remove key from ignition. Open door (RAP off). Disconnect Brown TBC module harness connector. Remove RAP relay (located in BBEC). Using DVOM, check voltage between ground and Brown TBC module harness connector terminal A7 (Black wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If battery voltage is present, go to step 7). If battery voltage is not present, go to next step.
  3. Check resistance between RAP relay connector terminals No. 85 (Red wire) and No. 87 (Red wire). If resistance is 5 ohms or less, go to step 8). If resistance is not 5 ohms or less, go to next step.
  4. Check resistance between RAP relay connector terminals No. 85 (Red wire) and No. 87A (Brown wire). If resistance is 5 ohms or less, go to step 8). If resistance is not 5 ohms or less, go to next step.
  5. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1478 is set as current code, go to next step. If DTC B1478 is not set as current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  6. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 9).
  7. Repair short to voltage in Black wire. After repairs, go to step 9).
  8. Replace RAP relay. After replacing relay, go to next step.
  9. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring and harness connectors for intermittent and poor connections.

TBC module monitors the voltage on circuit No. 1732 (Orange wire) as an input circuit. See WIRING DIAGRAMS . DTC will set when voltage in this circuit is low and TBC module is commanding circuit No. 1391 (Dark Blue wire) low. TBC module uses circuit No. 1393 (Dark Blue wire) to turn on the inadvertent power relay. Before TBC module goes to sleep, it turn off the relay. TBC module also monitors ignition switch position based on ignition signal inputs.

Conditions for setting DTC

  1. When TBC module is commanding circuit No. 1393 to ground and TBC receives a low input on circuit No. 1732 or a short to ground on circuit No. 1732.
  2. System voltage 9-16 volts.
  3. Conditions must be met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Ensure DTC B1480 is a current code. Check CTSY LP fuse (located in BBEC). If fuse is okay, go to next step. If fuse is open, go to step 11).
  3. Turn ignition switch to RUN then to OFF position. Using scan tool, ensure inadvertent power relay is on. If relay is on, go to step 24). If relay is not on, go to next step.
  4. Remove inadvertent power relay from BBEC. Turn ignition switch to RUN position. Check voltage between ground and BBEC cavity for inadvertent relay circuit No. 40. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If battery voltage is present, go to next step. If battery voltage is not present, go to step 12).
  5. Check resistance between relay terminals No. 1 and 2. If resistance is about 95 ohms, go to next step. If resistance is not about 95 ohms, go to step 15).
  6. Disconnect Brown TBC module harness connector. Check resistance between BBEC terminal C4 (Dark Blue wire) and TBC module harness connector terminal A8 (Dark Blue wire). If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 16).
  7. Connect a fused jumper wire between battery voltage and inadvertent power relay terminal No. 2. Connect another jumper between ground relay terminal No. 1, energizing relay. Check resistance between relay terminals No. 3 and 5. If resistance is about 2 ohms, go to next step. If resistance is not about 2 ohms, go to step 21).
  8. Check for poor connection from inadvertent power relay to BBEC. If connection is okay, go to next step. If connection is faulty, go to step 22).
  9. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1480 is set as a current code, go to next step. If DTC B1480 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  10. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 25).
  11. Ensure circuit No. 40 (Orange wire) between BBEC and courtesy light fuse is not shorted to ground. Repair as necessary and replace CTSY LP fuse. After repairs, clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. check DTCs. If DTC B1480 is set as a current code, go to step 23). If DTC B1480 is not set as a current code, go to step 25).
  12. Disconnect BBEC harness connector. Check voltage between ground and BBEC harness connector terminal A4 (Orange wire). If battery voltage is present, go to step 14). If battery voltage is not present, go to next step.
  13. Repair open in Orange wire between BBEC and courtesy light fuse. After repairs, go to step 25).
  14. Check for poor or loose connection at BBEC harness connector terminal A4 (Orange wire). Repair as necessary. After repairs, go to step 5). If terminal connection is okay, go to step 20).
  15. Replace inadvertent power relay. After replacing relay, go to step 25).
  16. Disconnect BBEC harness connector. Check resistance between BBEC harness connector terminal C4 (Dark Blue wire) and Brown TBC module harness connector terminal A8 (Dark Blue wire). If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 19).
  17. Check resistance between BBEC connector terminal C4 (Dark Blue wire) and inadvertent power relay cavity No. 1. If resistance is 2 ohms or less, go to next step. If resistance is not 2 ohms or less, go to step 20).
  18. Check for loose or poor connection at BBEC harness connector terminal C4. Repair as necessary. After repairs, go to step 25). If connector terminal is okay, go to step 20).
  19. Repair open in Dark Blue wire between BBEC and TBC module. After repairs, go to step 25).
  20. Replace BBEC. After replacing BBEC, go to step 25).
  21. Replace inadvertent power relay. After replacing relay, go to step 25).
  22. Repair poor connection. After repairs, go to step 25).
  23. Check for short to ground or open in circuit No. 1732 (Orange wire), including a short in any of the light request input circuits. Repair as necessary. After repairs, go to step 25). If circuits are okay, got step 10).
  24. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B1480 is set as a current code, go to step 23). If DTC B1480 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  25. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

The TBC module monitors circuit No. 192 (Orange) to determine if front foglight circuit is shorted to ground. See WIRING DIAGRAMS . When circuit is shorted to ground for 184 seconds, DTC will set. TBC module also monitors ignition switch position based on ignition signal inputs.

Conditions for setting DTC

  1. Circuit No. 192 is shorted to ground.
  2. System voltage 9-16 volts.
  3. Conditions present for 184 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Disconnect Purple TBC module harness connector. Disconnect front foglight switch connector. Check resistance between ground and Purple TBC module harness connector terminal No. B5 (Orange wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 6).
  3. DO NOT depress foglight switch button. Check resistance between foglight switch terminals "D" (Black wire) and "E" (Orange wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 7).
  4. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position for 3.5 minutes. Check DTCs. If DTC B2527 is set as a current code, go to next step. If DTC B2527 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  5. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 8).
  6. Repair short to ground in Orange wire. After repairs, go to step 8).
  7. Replace front foglight switch. After repairs, go to next step.
  8. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Check front foglight switch for sticking in ON position. Scan tool reads Class-II messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

The TBC module monitors circuit No. 187 (Light Blue) to determine if rear foglight circuit is shorted to ground. See procedures in WIRING DIAGRAMS . When circuit is shorted to ground for 184 seconds, DTC will set. TBC module also monitors ignition switch position based on ignition signal inputs.

Conditions for setting DTC

  1. Circuit No. 187 is shorted to ground.
  2. System voltage 9-16 volts.
  3. Conditions present for 184 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Disconnect Purple TBC module harness connector. Disconnect rear foglight switch connector. Check resistance between ground and Purple TBC module harness connector terminal No. B7 (Light Blue wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 6).
  3. DO NOT depress foglight switch button. Check resistance between foglight switch terminals "A" (Light Blue wire) and "B" (Black wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 7).
  4. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position for 3.5 minutes. Check DTCs. If DTC B2537 is set as a current code, go to next step. If DTC B2537 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  5. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 8).
  6. Repair short to ground in Light Blue wire. After repairs, go to step 8).
  7. Replace rear foglight switch. After repairs, go to next step.
  8. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Check rear foglight switch for sticking in ON position. Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

TBC module monitors voltage in circuit No. 352 (White wire) to determine if headlight power relay was requested ON. See WIRING DIAGRAMS . If voltage in this circuit is low and headlight request circuit (White wire) is pulled to ground, DTC will set. TBC module uses this circuit (White wire) to determine actual state of headlight power relay circuit. TBC module also monitors ignition switch position based on ignition signal inputs.

Conditions for setting DTC

  1. When there is short to ground in circuit No. 352 (White wire) and headlight relay was requested on.
  2. System voltage 9-16 volts.
  3. Conditions present for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Check HDLP SW fuse located in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, replace fuse and go to next step.
  3. Turn ignition off. Disconnect Light Blue TBC module harness connector. Turn headlight switch on. Check HDLP SW fuse. If fuse blows, go to next step. If fuse is okay, go to step 8).
  4. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Replace HDLP SW fuse. Turn headlights on. Check fuse. If fuse blows, go to next step. If fuse is okay, go to step 11).
  5. Disconnect 48-pin connector at steering column. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If resistance is infinite, go to step 12). If resistance is not infinite, go to next step.
  6. Disconnect connector C1 from underhood electrical center. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 14).
  7. Replace shorted underhood electrical center. After replacing underhood electrical center, go to step 15).
  8. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Check resistance between ground and Light Blue TBC harness connector terminal A11 (White wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 5).
  9. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B2575 is set as a current code, go to next step. If DTC B2575 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  10. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 15).
  11. Replace HDLP PWR relay. After replacing relay, go to step 15).
  12. Disconnect headlight switch connector. Check for short to ground in White wire between 48-pin harness connector and headlight switch connector. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to next step.
  13. Replace headlight switch assembly in steering column. After replacing switch, go to step 15).
  14. Repair short to ground in White wire between TBC harness connector terminal A11 and 48-pin steering column harness connector or between underhood electrical center connector C1 and 48-pin steering column harness connector E12. After repairs, go to next step.
  15. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Check rear foglight switch for sticking in ON position. Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

TBC module monitors voltage in circuit No. 352 (White wire) to determine if headlight power relay was requested ON. See WIRING DIAGRAMS . If battery voltage is not sensed in this circuit and TBC is requesting headlight relay on, DTC will set. TBC module uses this circuit (White wire) to determine actual state of headlight power relay circuit. TBC module also monitors ignition switch position based on ignition signal inputs.

Conditions for setting DTC

  1. Headlights in AUTO position.
  2. When there is short to ground in circuit No. 352 White wire).
  3. System voltage 9-16 volts.
  4. Conditions present for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Check HDLP SW fuse located in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, replace fuse and go to next step.
  3. Turn ignition off. Disconnect Light Blue TBC module harness connector. Turn headlight switch on. Check HDLP SW fuse. If fuse blows, go to next step. If fuse is okay, go to step 8).
  4. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Replace HDLP SW fuse. Turn headlights on. Check fuse. If fuse blows, go to next step. If fuse is okay, go to step 7).
  5. Disconnect 48-pin connector at steering column. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If resistance is infinite, go to step 11). If resistance is not infinite, go to step 13).
  6. Disconnect connector C1 from underhood electrical center. Check resistance between ground and Light Blue TBC module harness connector terminal A11 (White wire). If resistance is infinite, go to step 11). If resistance is not infinite, go to step 13).
  7. Replace HDLP PWR relay. After replacing relay, go to step 14).
  8. Turn headlight switch to AUTO position (if equipped). Remove HDLP PWR relay from underhood electrical center. Check resistance between ground and Light Blue TBC harness connector terminal A11 (White wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 5).
  9. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B2577 is set as a current code, go to next step. If DTC B2577 is not set as a current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  10. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 14).
  11. Disconnect headlight switch connector. Check for short to ground in White wire between 48-pin harness connector and headlight switch connector. Repair as necessary. After repairs, go to step 14). If circuit is okay, go to next step.
  12. Replace headlight switch assembly in steering column. After replacing switch, go to step 14).
  13. Repair short to ground in White wire between TBC harness connector terminal A11 and 48-pin steering column harness connector or between underhood electrical center connector C1 and 48-pin steering column harness connector E12. After repairs, go to next step.
  14. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Check rear foglight switch for sticking in ON position. Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

TBC module monitors voltage on circuit No. 2409 (Brown wire) between instrument panel fuse block and TBC module to determine actual state of the park light relay. See WIRING DIAGRAMS . TBC module also uses this circuit to turn on the park light relay. When voltage in circuits No. 1080 (White wire) and No. 2409 (Brown wire) is low, DTC will set.

Conditions for setting DTC

  1. Voltage on circuit No. 2409 is low or open and TBC module is requesting park lights on.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn headlight switch to AUTO position (if equipped). Using scan tool, ensure if vehicle is in LIGHT state when performing tests. Release parking brake. Using a dark tape, cover light sensor. Turn ignition to RUN position. If instrument panel light illuminates, go to step 12). If instrument panel light does not illuminate, go to next step.
  3. Turn ignition off. Check PARK LP fuse located in underhood electrical center. If fuse is okay, go to next step. If fuse is open, go to step 13).
  4. Check PARK LPS located in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, go to step 17).
  5. Disconnect Light Blue TBC module harness connector. Check resistance between BBEC cavity for park light relay circuit No. 1080 (White wire) and TBC module harness connector terminal A5 (White wire). See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 21).
  6. Check resistance between park light relay terminals No. 1 and 2. If resistance is 95 ohms or less, go to next step. If resistance is not 95 ohms or less, go to step 22).
  7. Remove PARK LPS fuse from instrument panel fuse block. Check resistance between BBEC cavity for park light relay circuit No. 74 (Light Blue wire) and PARK LPS fuse at fuse block terminal M6. If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 23).
  8. Using a fused jumper wire, connect park light relay terminal No. 2 to battery voltage and terminal No. 1 to ground. Check resistance between relay terminals No. 3 and 5. If resistance is 95 ohms or less, go to next step. If resistance is not 95 ohms or less, go to step 22).
  9. Check resistance between PARK LPS fuse terminal "B" and TBC module harness connector terminal B5. If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 25).
  10. Install PARK LPS fuse in fuse block. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B2585 is set as a current code, go to next step. If DTC B2585 is not set as current code, DTC is intermittent. See DIAGNOSTIC AIDS.
  11. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 26).
  12. Turn ignition off, then go to step 5).
  13. Replace PARK LPS fuse. Turn ignition switch to RUN position. Check fuse. If fuse blows, go to step 16). If fuse does not blow, go to next step.
  14. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check DTCs. If DTC B2585 is set as a current code, go to next step. If DTC B2585 is not set as current code, go to step 26).
  15. Remove tape covering light sensor, then go to step 4).
  16. Repair short to ground in Orange wire to BBEC. After repairs, go to step 26).
  17. Replace PARK LPS fuse. Remove tape covering light sensor. Turn ignition switch to RUN position. If fuse blows, go to step 19). If fuse does not blow, go to next step.
  18. Cover light sensor with dark tape. Check fuse. If fuse blows, go to step 20). If fuse does not blow, go to step 26).
  19. Repair short to ground in Brown wire between fuse block and TBC module. After repairs, go to step 26).
  20. Repair short to ground in Light Blue wire between BBEC and instrument panel fuse block. After repairs, go to step 26).
  21. Check for open in White wire between TBC module and BBEC. Repair as necessary. After repairs, go to step 26). If circuit is okay, go to step 24).
  22. Replace park light relay. After replacing relay, go to step 26).
  23. Repair open in Light Blue wire between BBEC and instrument panel fuse block. After repairs, go to step 26).
  24. Replace BBEC. After replacing BBEC, go to step 26).
  25. Repair open in Brown wire between TBC module and instrument panel fuse block. After repairs, go to next step.
  26. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Use an incandescent light or flashlight to force light sensor activate. Scan tool reads class 2 messages with ignition switch in RUN position. Use DVOM to compare scan tool values to actual values. Perform visual checks of wiring, fuses and harness connectors for intermittent, open and poor connections.

TBC monitors voltage on circuit No. 524 (Purple wire) to determine amount of voltage present in the high beam circuit. When circuit is shorted to battery voltage or ground and DRL are requested on, DTC will set. TBC module monitors circuit No. 524 (Purple wire) to determine if DRL are on or if high beams are on.

Conditions for setting DTC

  1. Circuit No. 524 is open or shorted to battery voltage or ground, and TBC module commands DRL relay on.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Using scan tool, check for current DTCs. If DTC B2647 or B2648 set as current code, diagnose using appropriate diagnostic test procedures. If DTC B2647 or B2648 is not set as current code, go to next step.
  3. If DTC B2577 is set as a current code, diagnose using DTC B2577 diagnostic test procedures. If DTC B2577 is not set as a current code, go to next step.
  4. Using scan tool, ensure vehicle is in Light state (light sensor). Turn ignition switch to RUN position. Turn headlight switch to AUTO position. Move beam selector to LOW beam position. Using DVOM, check voltage between ground and TBC module harness connector C2 terminal B5 (Purple wire). If voltage reading is less than 25 percent of battery voltage, go to step 6). If voltage reading is not less than 25 percent of battery voltage, go to next step.
  5. If voltage reading is greater than 75 percent of battery voltage, go to step 17). If voltage reading is not greater than 75 percent, but greater than 25 percent of battery voltage, go to step 18).
  6. Turn ignition off. Remove HDLP PWR relay located in underhood electrical center. Using scan tool, ensure vehicle is in Light state. Turn headlight switch on. Ensure beam selector is in LOW beam position. Check voltage in HDLP PWR relay feed circuits No. 42 and 352. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If battery voltage is present, go to next step. If battery voltage is not present, go to step 14).
  7. Check HDLP PWR relay. Using a fused jumper wire, connect jumper between battery positive and relay terminal No. 1. Connect relay terminal No. 2 to battery negative. Check continuity between relay terminals No. 3 and 5. If continuity is present, go to next step. If continuity is not present, go to step 24).
  8. Turn ignition off. Install HDLP PWR relay. Using scan tool, ensure vehicle is in Light state. Turn headlight switch on. Turn ignition switch to RUN position. Ensure beam selector is in LOW beam position. Remove both headlight fuses located in underhood electrical center. Check supply voltage between ground and LT HDLP fuse and RT HDLP fuse. If battery voltage is present on both circuits, go to next step. If battery voltage is not present on both circuits, go to step 16).
  9. Turn ignition off. Reconnect all components. Using scan tool, ensure vehicle is in Light state. Disconnect DRL relay located in underhood electrical center. Turn ignition switch to RUN position. Turn headlight switch on. Ensure beam selector is in LOW beam position. Check voltage between ground and DRL relay circuit No. 712 in underhood electrical center. If battery voltage is present, go to next step. If battery voltage is not present, go to step 16).
  10. Check DRL relay. Using a fused jumper wire, connect jumper between battery positive and DRL relay terminal No. 1. Connect relay terminal No. 2 to battery negative. Check continuity between relay terminals No. 3 and 5. If continuity is present, go to step 20). If continuity is not present, go to step 25).
  11. Ensure circuits for LT HDLP and RT HDLP fuses are not shorted to ground. Repair as necessary. Replace open fuse(s). After repairs, go to step 28). If circuits and fuses are okay, go to next step.
  12. Reconnect all components and wiring. Place headlight switch in AUTO position. Using scan tool, ensure vehicle is in Light state. Turn ignition switch from OFF to RUN position. Place beam selector in LOW beam position. Check for open or short in Purple wire between underhood electrical center to both high beam headlights. Check for faulty headlight bulb. Repair as necessary. After repairs, go to step 28). If circuits and headlight bulbs are okay, go to next step.
  13. Place headlight switch in AUTO position. Using scan tool, ensure vehicle is in Light state. Turn ignition switch from OFF to RUN position. Place beam selector in LOW beam position. Check for open or short in Purple wire from underhood electrical center to headlight switch and both high beam headlights. Repair as necessary. After repairs, go to step 28). If circuits are okay, go to step 19).
  14. Repair open in circuit(s) to underhood electrical center for HDLP PWR relay feed circuits No. 42 and 352, including headlight switch. After repairs, go to step 28).
  15. Repair open or short to voltage in Purple wire. After repairs, go to step 28).
  16. Replace underhood electrical center. After repairs, go to step 28).
  17. Repair short to voltage in Purple wire. After repairs, go to step 28).
  18. Using scan tool, ensure vehicle is in Light state. Turn ignition off. Disconnect TBC module harness connector C2. Remove circuit No. 524 (Purple wire) from harness connector. Reconnect TBC module harness connector. Check voltage between ground and TBC module harness connector circuit No. 524 (Purple wire). If voltage is 25-75 percent of battery voltage, go to next step. If voltage is not 25-75 percent of battery voltage, go to step 17).
  19. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 28).
  20. Ensure DRL relay is removed. Remove DRL diode located in underhood electrical center. Check continuity between DRL relay circuit No. 992 and DRL diode circuit No. 992 in electrical center cavities. If continuity is present, go to next step. If continuity is not present, go to step 16).
  21. Remove HDLP GND relay located in underhood electrical center. Check continuity between DRL relay circuit No. 592 and DRL diode circuit No. 592 in electrical center cavities. If continuity is present, go to next step. If continuity is not present, go to step 16).
  22. Check DRL diode. If diode is okay, go to next step. If diode is faulty, go to step 26).
  23. Disconnect TBC module harness connector C1. Check for short to ground in DRL diode circuit No. 592 and TBC module connector C1 terminal A11. If circuit is shorted, go to step 27). If circuit is okay, go to step 11).
  24. Replace HDLP PWR relay. After replacing relay, go to step 28).
  25. Replace DRL relay. After replacing relay, go to step 28).
  26. Replace DRL diode. After replacing diode, go to step 28).
  27. Repair short to ground in circuit No. 592 (Light Green/Black wire). After repairs, go to next step.
  28. Reconnect all components and wiring. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Scan tool can be used to command DRL relay on and to compare state of the DRL relay. Check for faulty headlight bulbs. Use an incandescent light or a flashlight to force light sensor to activate (Light state). Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors voltage on circuit No. 1220 (Gray wire). See WIRING DIAGRAMS . If circuit is shorted to voltage, DTC is set.

Conditions for setting DTC

  1. Circuit No. 1220 is shorted to battery voltage, park lights off.
  2. System voltage 9-16 volts.
  3. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Using scan tool, ensure vehicle is in Light state. Ensure parking brakes are not applied. Turn ignition switch from OFF to RUN position. Clear DTCs. Cover light sensor using dark tape. Headlights and park lights should turn on. Check if DTC B2585 is set as a current code. If code is current, go to step 6). If code is not current, go to next step.
  3. Turn ignition off. Apply parking brakes. Park lights should turn off. Turn headlight switch to AUTO position. Remove ILLUM fuse located in instrument panel fuse block. Turn ignition switch to RUN position. Check if DTC B2613 is set as a current code. If code is current, go to next step. If code is not current, go to step 7).
  4. Turn ignition off. Disconnect Purple TBC module harness connector. Turn ignition switch to RUN position. Using DVOM, check for short to battery voltage in circuit No. 1220 (Gray wire) between fuse block and TBC module harness connector. See «WIRING DIAGRAMS»(ref-33327-S31986024722001101600000) . If circuit is shorted, go to next step. If circuit is okay, go to step 8).
  5. Repair short to battery voltage in circuit. After repairs, go to step 9).
  6. Perform DTC B2585 diagnostic test procedures. Recheck if DTC B2613 is set as a current code. If DTC B2613 is set as a current code after performing DTC B2585 test, go to step 2). If DTC B2613 is not set as a current code, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .
  7. Replace headlight switch assembly. After replacing switch, go to step 9).
  8. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to next step.
  9. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Ensure DTC B2617 is set as a current code, dome light dimmer is not in full UP position, dome/interior lights override switch is on, doors are closed for 45 seconds and to remain closed for this test. Using scan tool, monitor courtesy light relay input. turn ignition switch to RUN position. If scan tool displays that courtesy light relay input as ACTIVE, go to next step. If scan tool does not display ACTIVE, DTC is intermittent. See DIAGNOSTIC AIDS.
  3. Turn ignition off. Remove courtesy light relay from BBEC. Ensure doors has been closed for 45 seconds and remains closed for this test. Disconnect Light Blue TBC module harness connector. Check resistance between BBEC cavity for courtesy light relay circuit No. 690 (Gray/Black wire) and TBC module harness connector circuit No. 690 (Gray/Black wire). If circuit is shorted to ground, go to step 7). If circuit is not shorted to ground, go to step 6).
  4. Turn ignition off. Reconnect all components and wiring. Turn ignition switch to RUN position. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Turn dimmer switch to ON position. Check if DTC B2617 is set as a current code. If code is set as current, go to next step. If code is not set as current, problem is intermittent. See DIAGNOSTIC AIDS.
  5. Reconnect all components and wiring. Replace TBC module. Program TBC and perform relearn procedure. See «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and TBC/BCM RELEARN PROCEDURE. After programming module, go to step 9).
  6. Check resistance between courtesy light relay terminals No. 2 and 3. If continuity is present, go to step 8). If continuity is not present, go to step 4).
  7. Repair short to ground or open in circuit No. 690 (Gray/Black wire). After repairs, go to step 9).
  8. Replace courtesy light relay. After replacing relay, go to next step.
  9. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off. Remove courtesy light relay from BBEC. Turn ignition switch to RUN position. Check voltage between BBEC cavity for courtesy light relay circuit No. 690 (Gray/Black wire) and ground. If battery voltage is present, go to step 7). If battery voltage is not present, go to next step.
  3. Check resistance between courtesy light relay terminals No. 1 and 5. If continuity is present, go to step 11). If continuity is not present, go to next step.
  4. Check resistance between courtesy light relay terminals No. 1 and 2. If resistance is 95 ohms or less, go to next step. If resistance is not 95 ohms or less, go to step 11).
  5. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Turn dimmer switch to ON position. Courtesy light relay should turn on. Check if DTC B2618 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  6. Turn ignition off. Disconnect Light Blue TBC module harness connector. Remove circuit No. 690 (Gray/Black wire) from harness connector. Reconnect harness connector to TBC module. Turn ignition switch to RUN position. Check voltage between ground and harness connector circuit No. 690. If battery voltage is present, go to step 10). If battery voltage is not present, go to step 8).
  7. Turn ignition off. Disconnect Light Blue TBC module harness connector. Remove circuit No. 690 (Gray/Black wire) from harness connector. Reconnect harness connector to TBC module. Turn ignition switch to RUN position. Check voltage between ground and harness connector circuit No. 690. If battery voltage is present, go to step 10). If battery voltage is not present, go to next step.
  8. Reconnect all components and wiring. Clear DTCs. turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2618 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  9. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 12).
  10. Repair short to battery voltage in Gray/Black wire. After repairs, go to step 12).
  11. Replace courtesy light relay. After replacing relay, go to next step.
  12. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Install scan tool. Using scan tool, check if DTC B1397 is set as a current code. If code is current, go to step 8). If code is not current, go to next step.
  3. Install scan tool. Turn ignition switch to RUN position. Using scan tool, monitor light sensor voltage. If voltage is .137 volt or less, go to next step. If voltage is not .137 volt or less, problem is intermittent. See DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect light sensor connector. Disconnect Purple TBC module harness connector. Check resistance between ground and TBC module harness connector terminals A6 (White wire) and A4 (Gray wire). If resistance is infinite on either circuit, go to next step. If resistance is not infinite on either circuit, go to step 9).
  5. Turn ignition off. Disconnect light sensor connector. Disconnect Purple TBC module harness connector. Check resistance between light sensor connector terminal "B" (White wire) and TBC module harness connector terminal A6 (White wire). Check resistance light sensor connector terminal "A" (Gray wire) and TBC module harness connector A4 (Gray wire). If resistance is infinite on either circuit, go to step 10). If resistance is not infinite on either circuit, go to next step.
  6. Replace light sensor. Reconnect all components and wiring. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2647 is set as a current code. If code is current, go to next step. If code is not current, go to step 11).
  7. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 11).
  8. Perform DTC B1397 diagnostic test procedures. After performing DTC B1397 tests, check if DTC B2647 is set as a current code. If code is current, go to step 3). If code is not current, go to step 11).
  9. Repair short to ground on circuit No. 278 (White wire) or on circuit No. 705 (Gray wire). After repairs, go to step 11).
  10. Repair open in circuit No. 278 (White wire) or on circuit No. 705 (Gray wire). After repairs, go to next step.
  11. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Install scan tool. Using scan tool, check if DTC B1398 is set as a current code. If code is current, go to step 7). If code is not current, go to next step.
  3. Install scan tool. Turn ignition switch to RUN position. Using scan tool, monitor light sensor voltage. If voltage is 4.78 volts or greater, go to next step. If voltage is not 4.78 volts or greater, problem is intermittent. See DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect light sensor connector. Disconnect Purple TBC module harness connector. Check voltage between ground and TBC module harness connector terminals A6 (White wire). If voltage reading is 4.78 volts or greater, go to step 8). If voltage reading is not 4.78 volts or greater, go to next step.
  5. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2648 is set as a current code. If code is current, go to step 9). If code is not current, go to next step.
  6. Replace light sensor. After replacing sensor, go to step 10).
  7. Perform DTC B1398 diagnostic test procedures. After performing DTC B1398 tests, check if DTC B2648 is set as a current code. If code is current, go to step 3). If code is not current, go to step 10).
  8. Repair short to battery voltage on circuit No. 278 (White wire). After repairs, go to step 10).
  9. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to next step.
  10. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

Circuit No. 28 (Black wire) is an input to the TBC module. See WIRING DIAGRAMS . TBC module monitors this circuit to determine if horn circuit is shorted to ground. When circuit is shorted to ground for 184 seconds, DTC will set.

Conditions for setting DTC

  1. Circuit No. 28 is shorted to ground and TBC module is not commanding horn relay on.
  2. System voltage 9-16 volts.
  3. Conditions met for 184 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition on. Using scan tool, check DTCs. DTC B2752 should be a current code. Turn ignition off. Disconnect Brown TBC module harness connector. Remove horn relay from underhood electrical center. Check resistance between ground and TBC module harness connector terminal A9 (Black wire). If resistance is infinite, problem is intermittent. See DIAGNOSTIC AIDS. If resistance is not infinite, go to next step.
  3. Disconnect 48-pin harness connector from base of steering column. Check resistance between ground and TBC module harness connector terminal A9 (Black wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 7).
  4. Check resistance between ground and 48-pin harness connector terminal A11 (Black wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 8).
  5. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position for 3.5 minutes. Check if DTC B2752 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  6. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 9).
  7. Repair short to ground in circuit No. 28 (Black wire) between TBC module harness connector and 48-pin harness connector at steering column. After repairs, go to step 9).
  8. Replace horn switch assembly. After replacing switch, go to next step.
  9. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 80 (Light Green wire) to determine if ignition key is in ignition switch. See WIRING DIAGRAMS . DTC will set when circuit is shorted to battery voltage or open, and ignition switch has been turned to RUN position.

Conditions for setting DTC

  1. Circuit No. 80 is shorted to battery voltage or is open when ignition switch has been turned to RUN position.
  2. Ignition 1 circuit voltage is shorted to battery voltage and ignition key is not in ignition switch.
  3. System voltage 9-16 volts.
  4. Conditions met for .5 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Install scan tool. Turn ignition switch to RUN position. Using scan tool, monitor ignition key in/out parameter. If scan tool indicates that key is in, go to next step. If scan tool does not indicate that key is in, go to step 8).
  3. Turn ignition off. Using scan tool, monitor ignition 1 status. If scan tool indicates that ignition is inactive, problem is intermittent. See DIAGNOSTIC AIDS. If scan tool does not indicate that ignition is inactive, go to next step.
  4. Check GAUGES fuse in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, go to step 16).
  5. Turn ignition off. Disconnect Brown TBC module harness connector. Turn ignition on. Check voltage between ground and TBC module harness connector terminal B2 (Pink wire). If battery voltage is present, go to step 19). If battery voltage is not present, go to next step.
  6. Turn ignition off. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2961 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  7. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 20).
  8. Turn ignition off. Disconnect 48-pin harness connector at base of steering column. Disconnect Light Blue TBC module harness connector. Check resistance between TBC module harness connector terminal B9 (Light Green wire) and 48-pin harness connector terminal B3 (Light Green wire). If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 13).
  9. Insert ignition key in ignition switch. Check resistance between 48-pin harness connector terminals B3 (Light Green wire) and B4 (Black wire). If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 14).
  10. Check resistance between ground and 48-pin harness connector terminal B4 (Black wire). If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 15).
  11. Reconnect all connectors. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2961 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  12. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 20).
  13. Repair open in circuit No. 80 (Light Green wire). After repairs, go to step 20).
  14. Replace ignition lock cylinder. After repairs, go to step 20).
  15. Repair open in or poor ground in circuit No. 1850 (Black wire). After repairs, go to step 20).
  16. Replace GAUGES fuse. Turn ignition switch to RUN position. Check fuse. If fuse blows, go to step 18). If fuse is okay, go to next step.
  17. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B2961 is set a current code. If code is current, go to step 5). If code is not current, go to step 2).
  18. Repair short to ground in circuit No. 39 (Pink wire). After repairs, go to step 20).
  19. Repair open or short to voltage in circuit No. 39 (Pink wire). After repairs, go to next step.
  20. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 461 (Orange wire) to determine if keyless entry data link circuit is low. See WIRING DIAGRAMS . When circuit is shorted to ground, DTC will set.

Conditions for setting DTC

  1. Circuit No. 461 shorted to ground.
  2. System Voltage 9-16 volts.
  3. Conditions met for .5 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Disconnect Remote Function Actuator (RFA) module harness connector from receiver. Turn ignition to RUN position, then to OFF position. Check voltage between ground and RFA harness connector terminal No. 2 (Orange wire). If battery voltage is not present, go to next step. If battery voltage is present, go to step 6).
  3. Disconnect Brown TBC module harness connector. Check resistance between ground and TBC module harness connector terminal B4 (Orange wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 7).
  4. Turn ignition off. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position. Check if DTC B3102 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  5. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 8).
  6. Replace RFA receiver. After replacing receiver, go to step 8).
  7. Repair short to ground in circuit No. 461 (Orange wire). After repairs, go to next step.
  8. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 195 (Light Blue wire) as an input to determine if door lock relay circuit is grounded. See WIRING DIAGRAMS . When circuit is shorted to ground, DTC will set.

Conditions for setting DTC

  1. Circuit No. 195 shorted to ground.
  2. System voltage 9-16 ohms.
  3. Conditions met for .25 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off. Remove door lock relay from BBEC. Check resistance between ground and BBEC cavity for door lock relay circuit No. 135 (Light Blue wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 5).
  3. Check resistance between BBEC cavities for door lock relay circuits No. 195 (Light Blue wire) and No. 295 (Gray wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 9).
  4. Check resistance between door lock relay terminals No. 1 and 3, terminals No. 1 and 4, and terminals No. 1 and 5. If resistance is infinite on all tests, go to next step. If resistance is not infinite on some/all tests, go to step 10).
  5. Disconnect Brown TBC module harness connector. Check resistance between ground and TBC module harness connector terminal A4 (Light Blue wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 8).
  6. Reconnect all components. Press LOCK button on RFA transmitter. Check DTCs if DTC B3137 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  7. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 11).
  8. Repair short to ground in circuit No. 195 (Light Blue wire), including a shorted door lock switch or door lock actuator. After repairs, go to step 11).
  9. Replace BBEC. After replacing BBEC, go to step 11).
  10. Replace door lock relay. After replacing relay, go to next step.
  11. Reconnect all components. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 195 (Light Blue wire) as an input to determine if door lock relay circuit is shorted to battery voltage. See WIRING DIAGRAMS . When circuit is shorted to battery voltage, DTC will set.

Conditions for setting DTC

  1. Circuit No. 195 shorted to battery voltage.
  2. System voltage 9-16 ohms.
  3. Conditions met for 184 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off. Disconnect Brown TBC module harness connector. Connect DVOM between ground and TBC module harness connector terminals A4 (Light Blue wire). Turn ignition to RUN position. If battery voltage is present, go to next step. If battery voltage is not present, go to step 4).
  3. Turn ignition off. Remove door lock relay from BBEC. Turn ignition switch to RUN position. Connect DVOM between ground and TBC module harness connector terminal A4 (Light Blue wire). If battery voltage is present, go to step 7). If battery voltage is not present, go to step 6).
  4. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position for 3.5 minutes. Check if DTC B3138 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  5. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 11).
  6. Check resistance between door lock relay terminals No. 1 and 3, terminals No. 1 and 4, and terminals No. 1 and 5. If resistance is infinite on all tests, go to step 9). If resistance is not infinite on some/all tests, go to step 10).
  7. Turn ignition off. Remove MIR/LKS fuse from instrument panel fuse block. Turn ignition switch to RUN position. Connect DVOM between ground and TBC module harness connector terminal A4 (Light Blue wire). If battery voltage is present, go to step 9). If battery voltage is not present, go to next step.
  8. Install MIR/LKS fuse. Turn ignition switch to RUN position. Connect DVOM between ground and TBC module harness connector terminal A4 (Light Blue wire). Observe DVOM. Disconnect left front then the right front door lock switch. Replace door lock switch causing a short to battery voltage. Replace fuse. After repairs, go to step 11).
  9. Repair short to battery voltage on circuit No. 195 (Light Blue wire), including shorted door lock switch or door lock actuator. After repairs, go to step 11).
  10. Replace door unlock relay. After replacing relay, go to next step.
  11. Reconnect all components. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 194 (White wire) as an input to determine if passenger door lock relay circuit is shorted to ground. See WIRING DIAGRAMS . When circuit is shorted to ground, DTC will set.

Conditions for setting DTC

  1. Circuit No. 194 shorted to ground.
  2. System voltage 9-16 ohms.
  3. Conditions met for .25 second.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off. Remove passenger door lock relay from BBEC. Check resistance between ground and BBEC cavity for passenger door lock relay circuit No. 194 (White wire). If resistance is infinite, go to step 3). If resistance is not infinite, go to step 5).
  3. Check resistance between BBEC cavities for passenger door lock relay circuits No. 194 (White wire) and No. 294 (Tan wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 9).
  4. Check resistance between passenger door lock relay terminals No. 1 and 3, terminals No. 1 and 4, and terminals No. 1 and 5. If resistance is infinite on all tests, go to next step. If resistance is not infinite on some/all tests, go to step 10).
  5. Disconnect Brown TBC module harness connector. Check resistance between ground and TBC module harness connector terminal A3 (White wire). If resistance is infinite, go to next step. If resistance is not infinite, go to step 8).
  6. Reconnect all components. Press LOCK button on RFA transmitter. Check if DTC B3137 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  7. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 11).
  8. Repair short to ground on circuit No. 194 (White wire), including shorted door lock switch or door lock actuator. After repairs, go to step 11).
  9. Replace BBEC. After replacing BBEC, go to step 11).
  10. Replace passenger door unlock relay. After replacing relay, go to next step.
  11. Reconnect all components. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

TBC module monitors circuit No. 194 (White wire) as an input to determine if passenger door lock relay circuit is shorted to battery voltage. See WIRING DIAGRAMS . When circuit is shorted to battery voltage, DTC will set.

Conditions for setting DTC

  1. Circuit No. 194 shorted to battery voltage.
  2. System voltage 9-16 ohms.
  3. Conditions met for 184 seconds.
  1. Perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) . After performing system check, go to next step.
  2. Turn ignition off. Disconnect Brown TBC module harness connector. Check voltage between ground and TBC module harness connector terminal A3 (White wire). If battery voltage is present, go to next step. If battery voltage is not present, go to step 7).
  3. Turn ignition off. Remove passenger door lock relay from BBEC. Check voltage between ground and TBC module harness connector terminal A3 (White wire). If battery voltage is present, go to step 9). If battery voltage is not present, go to step 6).
  4. Turn ignition off. Remove MIR/LKS fuse from instrument panel fuse block. Turn ignition switch to RUN position. Connect DVOM between ground and TBC module harness connector terminal A3 (White wire). If battery voltage is present, go to step 9). If battery voltage is not present, go to next step.
  5. Install MIR/LKS fuse. Turn ignition switch to RUN position. Connect DVOM between ground and TBC module harness connector terminal A3 (White wire). Observe DVOM. Disconnect left front then the right front door lock switch. If voltage reading goes away when a switch is disconnected, go to step 10). If voltage does not go away when a switch is disconnected, go to step 9).
  6. Turn ignition off. Check resistance between passenger door lock relay terminals No. 1 and 3, terminals No. 1 and 4, and terminals No. 1 and 5. If resistance is infinite on all tests, go to step 4). If resistance is not infinite on some/all tests, go to step 11).
  7. Reconnect all components. Clear DTCs. Turn ignition off for 10 seconds. Turn ignition switch to RUN position for 3.5 minutes. Check if DTC B3148 is set as a current code. If code is current, go to next step. If code is not current, problem is intermittent. See DIAGNOSTIC AIDS.
  8. Replace TBC module. Program TBC and perform relearn procedure. See procedures in «TBC MODULE PROGRAMMING/RPO CONFIGURATION»(ref-33327-S36111802372001101600000) and «TBC/BCM RELEARN PROCEDURE»(ref-33327-S39209332392001101600000) . After programming module, go to step 12).
  9. Repair short to battery voltage on circuit No. 194 (White wire), including shorted door lock switch or door lock actuator. After repairs, go to step 12).
  10. Replace door lock switch causing short to battery voltage go away. After repairs, go to step 12).
  11. Replace passenger door unlock relay. After replacing relay, go to next step.
  12. Reconnect all components. Clear DTCs. After clearing DTCs, perform TBC module diagnostic system check. See procedures in «TBC MODULE DIAGNOSTIC SYSTEM CHECK»(ref-33327-S33902290172001101600000) .

Scan tool can read class 2 messages with ignition switch in RUN position. Use a DVOM to compare scan tool values to actual values. Visually check wiring and connectors for intermittent or poor connections.

Modules connected to the class 2 serial data link monitor the link for serial communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive (State Of Health) messages are transmitted by each module on the class 2 serial data link about once every 2 seconds. When the modules does not detect a message on the Class-II serial data link that it expects to receive, DTC U1255 is set.

Conditions for setting DTC

  1. Voltage supplied to module is in the normal operating voltage range (about 9-16 volts).
  2. Class-II message that module expects to receive is not detected on data link.

Diagnosis of a current DTC U1255 is accomplished through the symptom, scan tool will not communicate with a Class-II device. An intermittent condition is likely to be caused by a short to ground on the serial data link.

When this DTC is set by the Truck body Control (TBC) module, the symptom is most likely to be that the engine does not run. When this DTC is set by the TBC module and the engine runs, this indicates that an ignition feed to either the TBC module/VCM/PCM is open.

Modules connected to the class 2 serial data link monitor the link for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive (State Of Health) messages are transmitted by each module on the class 2 serial data link about once every 2 seconds. When the modules detects no message and a high voltage on the class 2 serial data link for about 3 seconds, DTC U1301 is set and setting of all other class 2 serial communication DTCs is inhibited.

Conditions for setting DTC

  1. Voltage supplied to module is in normal operating voltage range about 9-16 volts).
  2. No valid Class-II messages detected on serial data link.
  3. Voltage level detected on Class-II serial data link is high.
  4. Conditions are all met simultaneously for 3 seconds.

This DTC cannot be retrieved with a current status. Diagnosis of a current DTC U1301 is accomplished through the symptom, scan tool will not communicate with a class 2 device. An intermittent condition is likely to be caused by a short to voltage on the serial data link.

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