Component Testing

WARNING: This page is about a different car, the 2017 GMC Yukon XL, 2017 GMC Yukon, 2017 Chevrolet Tahoe, and 2017 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

S77 Transfer Case Shift Control Switch

Ignition OFF. Remove the S77 transfer case shift control switch. Refer to Transfer Case Selector Switch Replacement (Chevrolet/GMC) Transfer Case Selector Switch Replacement (Cadillac) .

NOTE:

Testing for Step 2 is performed on the component using the L-BU probe J-35616-65B.

Measure the resistance for each of the range positions of the S77 transfer case shift control switch between the 5-volt reference circuit, terminal 11, and the switch signal circuit terminal 12.
- If the resistance is outside the specified ranges
  Replace the S77 transfer case shift control switch. Refer to Transfer Case Selector Switch Replacement (Chevrolet/GMC) Transfer Case Selector Switch Replacement (Cadillac) .
- If the resistance is within the specified ranges
S77 transfer case shift control switch OK.

S77 Transfer Case Range Selection Switch	Range	Nominal
2WD	1475 - 1550 Ω	1515 Ω
4WD/AWD Automatic	110 - 175 Ω	140 Ω
4WD High/Locked	625 - 700 Ω	665 Ω
4WD Low	2230 - 2400 Ω	2345 Ω
Neutral	990-1050 Ω	1020 Ω