Rick's Free Auto Repair Advice

Can’t shift out of park Equinox

Fix a can’t shift out of park condition Equinox

What is a shift interlock system?

The Equinox shift interlock system is designed to prevent the driver from shifting out of park without pressing the brake pedal first. When the system fails, you may be able to start the vehicle but you can’t shift out of park. This article is written for the Chevrolet Equinox, but is common to many GM vehicles,  SUV’s and trucks

How the GM shift interlock system works

The shift interlock system works with the body control module

can't shift out of park

Typical shift interlock solenoid

(BCM), the engine control module (ECM) and the transmission shift interlock solenoid. When you turn the key to START or RUN, the ECM checks the transmission range selector to determine if the transmission is in either PARK or NEUTRAL. If so, it sends a digital signal to the BCM confirming the transmission is in the correct position for starting. Once the BCM receives the confirmation signal from the ECM it checks for a signal from the brake pedal switch to confirm the driver’s foot is on the brake. If your foot is on the brake pedal, the BCM supplies battery voltage to the shift interlock solenoid, which moves a locking pin out of the way, allowing the driver to shift out of park. When there is NO power to the shift interlock solenoid, it defaults to the locked position, so you can’t shift out of park.

How to diagnose the BCM when you can’t shift out of park

Using a digital volt meter, locate the body control module

can't shift out of park

BCM

and check for battery voltage on the pink wire (pin 14) and the brown wire (pin 29). Next, check the IGN 0 signal on the white wire for 12 volts. Check the red/white wires at pins 3 and 10 for battery voltage. Check for good ground at black white wires at pins 1 and 5.

Using a bi-directional scan tool, monitor the shift lock command results from the BCM data. Apply the brake pedal and check for power going to the shift interlock solenoid on the dark green/white wire. Then check the shift interlock linkage to see if it is binding. That’s usually caused by a spilled soft drink

B2705 Gearshift unlock circuit

The BCM monitors voltage flow to the shift interlock solenoid when the key is in the START or RUN position and the brake pedal is depressed and the transmission is in the park position. The BCM will set a B2705 Gearshift unlock circuit if the BCM detects a short to ground condition at the shift interlock solenoid or the wiring. With the B2705 code set, you can’t shift out of park.

With the engine running, you should hear an audible click when you depress the brake pedal. That’s the shift interlock solenoid unlocking the shifter.

Most common causes of can’t shift out of park condition

• Failed BCM or BCM wiring

• Failed shift interlock solenoid or wiring

• Binding in shift mechanism due to spilled drink

Replace shift solenoid

Remove the console side panel trim. Disconnect the shift interlock electrical connector. Replace the shift solenoid

©, 2017 Rick Muscoplat

Posted on by Rick Muscoplat



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