Page 1 of 5 Pinpoint Tests Pinpoint Test V: Both Reversing Lamps Are Inoperative Refer to Wiring Diagrams Cell 93, Reversing Lamps for schematic and connector information. rmal Operation 4R70E/4R75E Transmission When the ignition switch is in the RUN position, voltage is supplied from the Battery Junction Box (BJB) fuse 54 (5A) to the digital Transmission Range (TR) sensor. When the transmission is in REVERSE (R), the digital TR sensor routes voltage to the reversing lamps relay coil. Battery voltage is supplied from the BJB fuse 43 (20A) to the reversing lamps relay switch side. When the reversing lamps relay is energized, voltage is routed to the reversing lamps. The reversing lamps share a common ground circuit. 6R80 Transmission/5.4L Engine Combination The reversing lamps relay coil power and ground are supplied and controlled by the Transmission Control Module (TCM) (also called the mechatronic assembly). When the transmission is in REVERSE (R), the TCM energizes the reversing lamps relay. Battery voltage is supplied from the BJB fuse 43 (20A) to the reversing lamps relay switch side. When the reversing lamps relay is energized, voltage is routed to the reversing lamps. The reversing lamps share a common ground circuit. 6R80 Transmission/6.2L Engine Combination The reversing lamps relay coil is supplied voltage when the PCM relay is energized (ignition system is in the RUN state). When the transmission is in REVERSE (R), the PCM provides ground to energize the reversing lamps relay. When the reversing lamps relay is energized, voltage is routed to the reversing lamps. The reversing lamps share a common ground circuit. This pinpoint test is intended to diagnose the following: Fuse Wiring, terminals or connectors Digital TR sensor adjustment (4R70E/4R75E transmission) Reversing lamps relay Digital TR sensor (4R70E/4R75E transmission) TCM (6R80 transmission/5.4l engine combination) PCM (6R80 transmission/6.2l engine combination) PINPOINT TEST V : BOTH REVERSING LAMPS ARE INOPERATIVE NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector. V1 CHECK FOR VOLTAGE TO THE LH REVERSING LAMP Disconnect: LH Reversing Lamp C487 (Styleside) or C451 (Flareside). Apply the parking brake. For Styleside vehicles, measure the voltage between the LH reversing lamp C487-1, circuit CAT16 (GY/BN), harness side and ground. For Flareside vehicles, measure the voltage between the LH reversing lamp C451-3, circuit CAT16 (GY/BN), harness side and ground. REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation. GO to V2. V2 CHECK THE REVERSING LAMPS RELAY Connect: LH Reversing Lamp C487 (Styleside) or C451 (Flareside). Disconnect: Reversing Lamps Relay. Substitute a known good relay. REMOVE the known good relay. INSTALL a new reversing lamps relay. TEST the system for normal operation. REMOVE the known good relay. GO to V3.

Page 2 of 5 V3 CHECK FOR VOLTAGE TO THE REVERSING LAMPS RELAY (SWITCH SIDE) Measure the voltage between the reversing lamps relay pin 3, circuit SBB43 (BU/RD), BJB face side and ground. GO to V4. VERIFY the BJB fuse 43 (20A) is OK. If OK, REPAIR circuit SBB43 (BU/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams Manual to identify the possible causes of the circuit short. V4 BYPASS THE REVERSING LAMPS RELAY Connect a fused jumper wire between the reversing lamps relay pin 3, circuit SBB43 (BU/RD), BJB face side and the reversing lamps relay pin 5, circuit CAT16 (GY/BN), BJB face side. REMOVE the jumper wire. For vehicles with a 4R70E/4R75E transmission, GO to V5. For vehicles with a 6R80 transmission/5.4l engine combination, GO to V9. For vehicles with a 6R80 transmission/6.2l engine combination, GO to V12. REMOVE the jumper wire. REPAIR circuit CAT16 (GY/BN) for an open. TEST the system for normal operation. V5 CHECK FOR VOLTAGE TO THE REVERSING LAMPS RELAY COIL (4R70E/4R75E TRANSMISSION) Measure the voltage between the reversing lamp relay pin 1, circuit CET47 (BU), BJB face side and ground. REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation. GO to V6. V6 CHECK FOR VOLTAGE TO THE DIGITAL TR SENSOR Connect: Reversing Lamps Relay. Disconnect: Digital TR Sensor C167. Measure the voltage between the digital TR sensor C167-9, circuit CBB54 (VT/OG), harness side and ground.

Page 3 of 5 GO to V7. VERIFY the BJB fuse 54 (5A) is OK. If OK, REPAIR circuit CBB54 (VT/OG) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams Manual to identify the possible causes of the circuit short. V7 BYPASS THE DIGITAL TR SENSOR Connect a fused jumper wire between the digital TR sensor C167-9, circuit CBB54 (VT/OG), harness side and the digital TR sensor C167-11, circuit CET47 (BU), harness side. REMOVE the jumper wire. GO to V8. REMOVE the jumper wire. REPAIR circuit CET47 (BU) for an open. TEST the system for normal operation. V8 CHECK THE DIGITAL TR SENSOR ADJUSTMENT Check the digital TR sensor alignment. Refer to Section 307-01A. Is the digital TR sensor aligned correctly? INSTALL a new digital TR sensor. REFER to Section 307-01A. TEST the system for normal operation. ADJUST the digital TR sensor. REFER to Section 307-01A. TEST the system for normal operation. V9 CHECK THE REVERSING LAMPS RELAY COIL CIRCUITS FOR A SHORT TO VOLTAGE Disconnect: TCM C1575. Measure the voltage between the reversing lamps relay pin 1, circuit CET41 (BN/YE), BJB face side and ground; and between the reversing lamps relay pin 2, circuit CLS28 (BU/WH), BJB face side and ground. Is any voltage present? REPAIR the circuit in question for a short to voltage. CLEAR the DTCs. REPEAT the self-test. GO to V10. V10 CHECK THE REVERSING LAMPS RELAY COIL CIRCUITS FOR A SHORT TO GROUND Measure the resistance between the reversing lamps relay pin 1, circuit CET41 (BN/YE), BJB face side and ground; and between the reversing lamps relay pin 2, circuit CLS28 (BU/WH), BJB face side and ground.

Page 4 of 5 Are the resistances greater than 10,000 ohms? GO to V11. REPAIR the circuit in question for a short to ground. CLEAR the DTCs. REPEAT the self-test. V11 CHECK THE REVERSING LAMPS RELAY COIL CIRCUITS FOR AN OPEN Measure the resistance between the reversing lamps relay pin 1, circuit CET41 (BN/YE), BJB face side and the TCM C1575-7, circuit CET47 (BU), harness side. Measure the resistance between the reversing lamps relay pin 2, circuit CLS28 (BU/WH), BJB face side and the TCM C1575-15, circuit CLS28 (BU/WH), harness side. Are the resistances less than 5 ohms? GO to V15. REPAIR the circuit in question for an open. CLEAR the DTCs. REPEAT the self-test. V12 CHECK FOR VOLTAGE TO THE REVERSING LAMPS RELAY COIL (6R80 TRANSMISSION) Measure the voltage between the reversing lamp relay pin 1, circuit CBB77 (WH), BJB face side and ground. GO to V13. REPAIR circuit CBB77 (WH) for an open. TEST the system for normal operation. V13 CHECK THE REVERSING LAMPS RELAY COIL GROUND CONTROLLED CIRCUIT FOR A SHORT TO VOLTAGE Disconnect: PCM C1381B. Measure the voltage between the reversing lamp relay pin 2, circuit CLS28 (BU/WH), BJB face side and ground. Is any voltage present? GO to V14. REPAIR circuit CLS28 (BU/WH) for a short to voltage. TEST the system for normal operation. V14 CHECK FOR VOLTAGE TO THE PCM Connect: Reversing Lamps Relay.

Page 5 of 5 Measure the voltage between the PCM C1381B-63, circuit CLS28 (BU/WH), harness side and ground. GO to V16. REPAIR circuit CLS28 (BU/WH) for an open. TEST the system for normal operation. V15 CHECK FOR CORRECT TCM OPERATION Disconnect the TCM connector. Check for: corrosion damaged pins pushed-out pins Connect the TCM connector and make sure it seats correctly. Operate the system and verify the concern is still present. Is the concern still present? INSTALL a new TCM. REFER to Section 307-01B, Mechatronic Assembly. TEST the system for normal operation. The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR any DTCs. REPEAT the self-test. V16 CHECK FOR CORRECT PCM OPERATION Disconnect the PCM connectors. Check for: corrosion damaged pins pushed-out pins Connect the PCM connectors and make sure they seat correctly. Operate the system and verify the concern is still present. Is the concern still present? INSTALL a new PCM. REFER to Section 303-14. TEST the system for normal operation. The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR any DTCs. REPEAT the self-test.