2021 GMC Terrain SLFACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

Unwanted or inadvertent door lock/unlock activation may be requested by the OnStarĀ® Remote Link app. It is possible that a customer may be unaware of account usage, result in an unwanted or phantom door lock/unlock. If normal system diagnosis does results in an inability to verify the customer's concern, contact Technical Assistance Center (TAC).

A low transmitter battery may cause a system malfunction. More often a malfunction is the result of radio frequency (RF) interference from aftermarket devices which could include unexpected items such as nearby flat screen televisions, darkness sensing flood lights, or nearby cell phones. Other more common items that can cause a malfunction are 2-way radios, power inverters, cellular phone chargers, computers, 12 V power outlet USB adapters, etc. High RF traffic areas, such as gas stations which use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction.

Conditions caused by external influences such are these are considered to be normal. Following this diagnostic will not diagnose an RF interference condition. If RF interference is suspected, question the customer about the conditions or location where the malfunction condition occurs.

The passive entry system will not function if the active entry system has a fault. Verify the active entry system operates before diagnosing the passive system.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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