NOTE: After repair or component replacement is completed, perform MEMORY SYSTEM CHECK under TESTING - SYSTEM CHECKS to verify system is operating properly.

Perform MEMORY SYSTEM CHECK under TESTING - SYSTEM CHECKS. Go to next step.
Disconnect Memory Seat Module (MSM) Light Green, 6-pin connector C2. See Fig 1 . Using DVOM, check voltage between MSM harness connector C2, terminals "D" (Orange wire) and "C" (Black wire). If about 12 volts exists, go to next step. If about 12 volts does not exist, go to step 5).
Disconnect left lumbar switch connector. Check voltage between MSM harness connector C2, terminal "D" (Orange wire) and left lumbar switch harness connector terminal "E" (Black wire). If about 12 volts exists, go to next step. If about 12 volts does not exist, go to step 6).
Replace left lumbar switch. See SEATS - POWER article.
Repair open in circuit No. 850 (Black wire) between MSM and splice S351. See WIRING DIAGRAMS .
Repair open in circuit No. 850 (Black wire) between left lumbar switch and splice S351. See WIRING DIAGRAMS . Perform MEMORY SYSTEM CHECK .

Fig 1: Connector C2 (Light Green), C3 (Black) & C4 (Natural)
Courtesy of GENERAL MOTORS CORP.

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.

Safety Warning

Left Lumbar Support Does Not Manually Move In Any Direction

Use the Manual With the Right Hardware

When to See a Mechanic