Code
B2110
HUMMER
B — Body
Lumbar Forward Switch Failed
AI status
Completed
Completed
100%
Causes
- Faulty lumbar forward switch (worn contacts or internal failure)
- Open or shorted wiring between switch and seat/BCM
- Poor connector connection or corrosion at switch or module
- Blown fuse or poor power/ground to seat switch circuit
- Faulty seat control module or body control module (rare)
- Software or calibration fault
Symptoms
- Lumbar support will not move forward when switch is pressed
- No audible motor noise when attempting lumbar forward
- Intermittent or inconsistent lumbar operation
- Other seat position functions may operate normally or may be affected
- Stored B2110 (and possibly related seat circuit codes) in memory
What to check
- Retrieve freeze frame and full DTC list with a scan tool; note any related codes
- Verify battery voltage is within normal range (12–14 V) before testing
- Visually inspect switch, harness, and connectors for damage, corrosion, or contamination
- Operate the switch while observing connector and harness for continuity or obvious movement issues (wiggle test)
- Listen for motor operation when commanding lumbar forward
- Check relevant fuses and power/ground at seat circuit connectors
Signal parameters
- Supply voltage to switch: approx. battery voltage (~11–14 V) when key on
- Switch output: logic/voltage change when pressed (0 V to ~12 V or ground switching depending on design)
- Continuity/closed-circuit resistance across switch contacts: near 0 Ω when actuated
- Open-circuit resistance: large/OL when not actuated
- CAN/serial message present to seat module (if equipped) when switch is operated
Diagnostic algorithm
- Connect a diagnostic scan tool, confirm B2110 and note any additional seat/body codes. Clear codes and attempt to reproduce.
- Verify battery voltage; low voltage can cause false failures. Recharge if necessary and retest.
- Inspect the lumbar switch and connector for physical damage, corrosion, or water ingress. Repair or replace damaged connectors/harness sections.
- With ignition ON, backprobe the switch connector. Verify supply voltage and change of signal while pressing the forward switch. If expected signals are present, suspect downstream motor or module.
- If no signal change at the switch, remove switch and bench-test for continuity while actuating. Replace switch if internal contact failure is found.
- If switch bench-test is good but no signal at module, check continuity between switch connector and seat/BCM input. Repair any opens or shorts.
- Verify good ground(s) for the seat/seat module circuits. Repair poor ground connections.
- If wiring is good and switch signals reach the module, command the lumbar motor via scan tool and monitor motor current/voltage. Replace motor or regulator if it fails to respond.
- If all hardware checks OK, check for software updates or module calibration at the dealer. Consider replacing seat control module only after confirming upstream components are good.
- After repairs, clear codes and perform a full function check and road/operation test to ensure the fault does not return.
Likely causes
- Defective switch assembly (most common)
- Broken/abraded wire in harness near seat or door opening
- Connector pins pushed out, bent, or corroded
- Intermittent ground or supply voltage to the switch
- Failed seat control module output or input circuit
Fault status
Status
Lumbar forward switch — circuit malfunction detected. Replace/repair switch, wiring, or control module as required after diagnosis.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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