There may be an intermittent Shift to Park message displayed on the Driver Information Center (DIC) when the vehicle has been shifted to Park and the ignition has been turned to the Off position (Fig. 32) on some 2016-2019 Malibu, Volt; 2017-2019 Acadia; 2018-2019 Traverse; and 2019 Blazer models. The Shift to Park message may be the result of a build-up of material on the contacts of the Park switch when it is activated in the transmission control (shifter) assembly. The excessive material may cause a higher than expected resistance in the signal circuit to the Body Control Module (BCM), and not allow the BCM to electronically see that the vehicle is in Park, even though the vehicle transmission is in the Park position.
Fig. 32
If this condition is present, the BCM will turn on the Shift to Park message and not allow the ignition to turn off, leaving the ignition in Accessory mode. To reduce the inrush of current that causes the excessive build-up on the contacts, install an in-line shifter wiring harness jumper (Fig. 33) between the shifter base connector and the console harness connector.
Fig. 33
Clean the Electrical Contacts
With the vehicle in Park and the ignition off, remove the transmission control (shifter) lever knob and boot assembly. (Fig. 34)
Fig. 34
Next, clean the Park Switch electrical contacts by depressing the actuation rod fully and then releasing the rod. Use the flat side of a trim stick or your thumb and allow the rod to “snap” back to the full up position. (Fig. 35) Repeat the cleaning procedure 50 times. It’s critical to clean the electrical contacts to ensure a proper repair.
Fig. 35
After completing the cleaning procedure, start the vehicle and verify that the Shift to Park message is not displayed on the DIC. If the Shift to Park message is still displayed, replace the transmission control (shifter) assembly. A newly design transmission control assembly is now available.
Install Jumper Harness
If the Shift to Park message is not displayed, install the jumper harness. Remove the front floor console trim plate and disconnect the body harness from the transmission control assembly. (Fig. 36)
Fig. 36
TIP: To gain access to the shift control wiring connector, it will be necessary to remove only the front floor console trim plate. However, on some models, it may be necessary to remove the front floor console trim plate and reposition the console assembly
Install the in-line shifter wiring harness jumper between the shifter base connector and the console harness connector. The jumper harness should not be twisted or kinked in a 90 degree position. (Fig. 37)
Fig. 37
Start the vehicle and verify that the Shift to Park message is not displayed. Reinstall the front floor console trim plate and any other trim panels as well as the transmission control lever knob and boot assembly.
Refer to Bulletin #19-NA-206 for additional information and part numbers.
– Thanks to Tom Burlingame
