DTC B15D7 or B15D8

Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC B15D7 02 Hands-Free Liftgate Sensor Signal 1 General Signal Malfunction DTC B15D8 02 Hands-Free Liftgate Sensor Signal 2 General Signal Malfunction Diagnostic Fault Information

Circuit number	Circuit Function	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performan
4840	B+	U1510 00	U1510 00	—	—
4898	Signal	B15D7 02	B15D7 02	B15D7 02	B15D7 08
4900	Signal	B15D8 02	B15D8 02	B15D8 02	B323B 08
4897	Low Reference	B15D7 02	B15D7 02	B15D7 02	B15D7 08
4899	Low Reference	B15D8 02	B15D8 02	B15D8 02	B323B 08
1450	Ground	—	U1510 00	—	—

Circuit/System Description The power liftgate has a feature that detects the motion of a foot under the rear fascia, this allows the operator to open the liftgate when his or her hands are full of packages. As an indicator that the action has been properly preformed, the rear closure hands-free module will send a serial data message to the rear gate module to command the liftgate to release and power open and the rear gate module will send a serial data message to the lighting control module to command the tail lights to flash 3 times Conditions for Running the DTC Battery voltage is between 9–16 V. Conditions for Setting the DTC B15D7 02 The rear gate control module has received a serial data message that an invalid signal from the upper hands free sensor has been detected by the rear closure hands-free module. The condition must be present for greater than 30 seconds B15D8 02 The rear gate control module has received a serial data message that an invalid signal from the lower hands free sensor has been detected by the rear closure hands-free module. The condition must be present for greater than 30 seconds. Action Taken When the DTC Sets The hands-free feature will be inoperative Conditions for Clearing the DTC The DTC will be current for as long as the fault is present. When the fault is no longer present, the DTC will be a history DTC. A history DTC will clear after 40 ignition cycles. Diagnostic Aids The hands-free function will only be allowed if certain operating criteria are met. Any of the following may cause the hands-free system not to function: The hands-free function has been disabled by a setting in the Vehicle Personalization menu The keyless entry transmitter is not within range The kicking motion is incorrectly preformed The interior liftgate control switch has not been set to the 3/4 or Max position A loose or misaligned hands-free sensor Reference Information Schematic Reference Liftgate Schematics Connector End View Reference Master Electrical Component List Description and Operation Liftgate Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

Ignition ON.

Verify the tail lights flash 3 times and the power liftgate opens while performing a kicking motion behind and under the rear fascia. ⇒ If the tail lamps flash but the liftgate does not open Refer to Liftgate System Diagnosis ⇒ If the tail lamps do not flash Refer to Circuit/System Testing. ⇓ If the tail lamps flash and the liftgate does open
A fault that is not currently present may have been caused by a intermittent condition. Circuit/System Testing
Ignition OFF, disconnect the X2 harness connector at the K171 Hands-Free Liftgate Sensor Control Module.
Test for less than 1 V between the B275A Hands-Free Liftgate Sensor—Upper signal circuit terminal 3 and ground ⇒ If 1 V or greater Replace the B275A Hands-Free Liftgate Sensor—Upper ⇓ If less than 1 V
Test for less than 1 V between the B275A Hands-Free Liftgate Sensor—Upper signal circuit terminal 4 and ground ⇒ If 1 V or greater Replace the B275A Hands-Free Liftgate Sensor—Upper ⇓ If less than 1 V
Test for infinite resistance between the B275A Hands-Free Liftgate Sensor—Upper signal circuit terminal 3 and ground. ⇒ If not the specified value Replace the B275A Hands-Free Liftgate Sensor—Upper ⇓ If infinite resistance
Test for infinite resistance between the B275A Hands-Free Liftgate Sensor—Upper signal circuit terminal 4 and ground. ⇒ If not the specified value Replace the B275A Hands-Free Liftgate Sensor—Upper ⇓ If infinite resistance
Test for less than 1 Ω between the B275A Hands-Free Liftgate Sensor—Upper signal circuit terminal 3 and the signal circuit terminal 4. ⇒ If 1 Ω or greater Replace the B275A Hands-Free Liftgate Sensor—Upper ⇓ If less than 1 Ω
Test for less than 1 V between the B275B Hands-Free Liftgate Sensor—Lower signal circuit terminal 1 and ground ⇒ If 1 V or greater Replace the B275B Hands-Free Liftgate Sensor—Lower ⇓ If less than 1 V
Test for less than 1 V between the B275B Hands-Free Liftgate Sensor—Lower signal circuit terminal 2 and ground ⇒ If 1 V or greater Replace the B275B Hands-Free Liftgate Sensor—Lower ⇓ If less than 1 V
Test for infinite resistance between the B275B Hands-Free Liftgate Sensor—Lower signal circuit terminal 1 and ground. ⇒ If not the specified value Replace the B275B Hands-Free Liftgate Sensor—Lower ⇓ If infinite resistance
Test for infinite resistance between the B275B Hands-Free Liftgate Sensor—Lower signal circuit terminal 2 and ground. ⇒ If not the specified value Replace the B275B Hands-Free Liftgate Sensor—Lower ⇓ If infinite resistance
Test for less than 1 Ω between the B275B Hands-Free Liftgate Sensor—Lower signal circuit terminal 1 and the signal circuit terminal 2. ⇒ If 1 Ω or greater Replace the B275B Hands-Free Liftgate Sensor—Lower ⇓ If less than 1 Ω
If all circuits test normal, replace the K171 Hands-Free Liftgate Sensor Control Module. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair Rear Closure Hands Free Sensor Replacement Control Module References for rear closure hands-free sensor module replacement, programming and setup