Shift Lever Can Be Moved without Brake Pedal Depressed. GMC Truck GMC K Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2006 🢒 GMC K Sierra - 4WD 🢒 Transmission/Transaxle 🢒 Shift Lock Control 🢒 Shift Lever Can Be Moved without Brake Pedal Depressed

Shift Lever Can Be Moved without Brake Pedal Depressed w/o Allison Transmission

Step	Action	Yes	No
Schematic Reference: Shift Lock Control Schematics Connector End View Reference: Master Electrical Component List DEFINITION: Transmission shift lever does not lock in the PARK position with the ignition ON and the brake pedal not pressed.
1	Did you perform the Symptoms - Automatic Transmission Shift Lock Control tests and all the necessary inspections?	Go to Step 2	Go to Symptoms - Automatic Transmission Shift Lock Control
2	Apply the parking brake and block the wheels. Turn ON, the ignition, with the engine OFF. Attempt to move the shift lever out of the PARK position. Does the shift lever move out of the PARK position?	Go to Step 3	Go to Testing for Intermittent Conditions and Poor Connections
3	Turn OFF the ignition. Ensure transmission shift lever is in the PARK position. Connect a test lamp between the A/T shift lock switch supply voltage circuit at the BTSI fuse and a good ground. Turn ON the ignition, with the engine OFF. Does the test lamp illuminate?	Go to Step 4	Go to Step 8
4	Connect a test lamp between the A/T shift lock switch supply voltage circuit at the automatic transmission shift lock control switch and a good ground. Does the test lamp illuminate?	Go to Step 5	Go to Step 14
5	Connect a test lamp between the A/T shift lock solenoid control circuit at the automatic transmission shift lock control switch and a good ground. Press and release the brake pedal several times. Does the test lamp turn ON and OFF with the brake pedal?	Go to Step 6	Go to Step 11
6	Connect a test lamp between the automatic transmission shift lock control solenoid supply voltage circuit at the automatic transmission shift lock control solenoid and a good ground. Does the test lamp illuminate?	Go to Step 7	Go to Step 15
7	Test the automatic transmission shift lock control solenoid ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 20	Go to Step 12
8	Turn OFF the ignition. Disconnect the park/neutral position switch connector. Connect a test lamp between the ignition 1 voltage circuit of the park/neutral position switch and a good ground. Turn ON the ignition, with the engine OFF. Does the test lamp illuminate?	Go to Step 9	Go to Step 13
9	Turn OFF the ignition. Connect a 10 amp fused jumper between the ignition 1 voltage circuit of the park/neutral position switch and the park/neutral position switch park signal circuit at the park/neutral position switch connector. Connect a test lamp between the A/T shift lock switch supply circuit at the BTSI fuse and a good ground. Turn ON the ignition, with the engine OFF. Does the test lamp illuminate?	Go to Step 10	Go to Step 16
10	Inspect for proper park/neutral position switch adjustment. Refer to Park/Neutral Position Switch Adjustment for the 4L60-E transmission or Park/Neutral Position Switch Adjustment for the 4L80-E transmission. Inspect for poor connections at the harness connector of the park/neutral position switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 20	Go to Step 17
11	Inspect for poor connections at the harness connector of the automatic transmission shift lock control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 20	Go to Step 18
12	Inspect for poor connections at the harness connector automatic transmission shift lock control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 20	Go to Step 19
13	Repair the open or short in the ignition 1 voltage circuit of the park/neutral position switch. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 20	--
14	Repair the open or short in the A/T shift lock switch supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 20	--
15	Repair the open in the A/T shift lock control solenoid supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 20	--
16	Repair the open or short in the park/neutral position switch park signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 20	--
17	Replace the park/neutral position switch. Refer to Park/Neutral Position Switch Replacement for the 4L60-E transmission or Park/Neutral Position Switch Replacement for the 4L80-E transmission. Did you complete the replacement?	Go to Step 20	--
18	Replace the automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement . Did you complete the replacement?	Go to Step 20	--
19	Replace the automatic transmission shift lock control solenoid. Refer to Automatic Transmission Shift Lock Control Actuator Replacement . Did you complete the replacement?	Go to Step 20	--
20	Operate the system in order to verify the repair. Did you find and correct the condition?	System OK	Go to Step 2

Shift Lever Can Be Moved without Brake Pedal Depressed with Allison Transmission

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

With the ignition in the ON position and the shift lever is in PARK, battery positive voltage is supplied from the body control module (BCM) to the automatic transmission shift lock control solenoid through the normally-closed automatic transmission shift lock control switch. When the transmission control module (TCM) indicates the shift lever is in the PARK position, the engine control module (ECM)/powertrain control module (PCM) sends a class 2 serial data message to the BCM indicating the transmission is in the PARK position. This allows current to flow through the switch to the automatic transmission shift lock control solenoid. Since the automatic transmission shift lock control solenoid is permanently grounded, the shift lock control solenoid energizes, locking the shift linkage in the PARK position. When the driver presses the brake pedal, the contacts in the automatic transmission shift lock control switch open, causing the automatic transmission shift lock control solenoid to de-energize, unlocking the shift lever from the PARK position.

Reference Information

Schematic Reference

Shift Lock Control Schematics

Connector End View Reference

Shift Lock Control Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Circuit/System Verification

With a scan tool, monitor the Trans. Range Sw. data to verify vehicle is in the Park position.

⇒	If data does not display Park, replace the internal mode switch (IMS). Refer to Transmission Internal Mode Switch Replacement .

Circuit/System Testing

With the ignition ON, connect a test lamp between the A/T shift lock solenoid ground and supply voltage. Verify test lamp illuminates.

⇒	If the test lamp does not turn ON, repair the ground circuit.

With the ignition ON, connect a test lamp between the A/T shift lock solenoid supply power and a good ground. Verify the test lamp does not illuminate.

⇒	If the test lamp turns ON, replace the A/T shift lock solenoid.

Test the stop lamp switch for proper operation and supply power from the BCM.

⇒	If testing indicates no supply power from the BCM, refer to Circuit/System Verification.

If no trouble found in circuit, replace the BCM.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Stop Lamp Switch Replacement

•	Automatic Transmission Shift Lock Control Actuator Replacement

•	Transmission Internal Mode Switch Replacement

•	Body Control Module Replacement for BCM