Code
B2106
HUMMER
B — Body
Horizontal Forward Switch Failed
AI status
Completed
Completed
100%
Causes
- Failed/open/shorted horizontal forward switch
- Corroded, loose or damaged connector at the switch
- Broken or chafed wiring between switch and control module
- Faulty ground or loss of reference voltage to the switch
- Blown fuse or faulty relay feeding the circuit
- Faulty body control module (BCM) or seat/module that reads the switch
Symptoms
- Forward horizontal function (seat, mirror, or trim item) does not operate or is intermittent
- Switch produces no response or only works in other directions
- One-touch or memory position functions fail or behave erratically
- DTC stored and may illuminate a message on the instrument panel
- Function works when the switch is held in a different position or after manipulating connector
What to check
- Retrieve DTC(s) and related freeze-frame/ignition state with a scan tool
- Attempt to duplicate symptom and observe exact conditions
- Visually inspect switch, connector, and wiring for damage, corrosion, pin push-out or water intrusion
- Check relevant fuses and relays for continuity and correct operation
- Check for other related DTCs that could indicate module or supply issues
- Perform wiggle test on harness and connector while operating switch to reveal intermittent faults
Signal parameters
- Reference voltage to switch: typically a regulated ~5 V reference or vehicle battery (approx. 12 V) depending on design — verify with service data
- Switch output when actuated: toggles to near ground or to reference voltage (0 V or ~5 V/12 V) — check expected logic with manufacturer data
- Switch resistance: closed position near 0 ohms; open position high resistance (kΩ to MΩ range) — compare to spec
- Continuity: harness pins should show continuity to control module inputs with connector disconnected
- No-load current draw: small or negligible when switch idle; larger only while actuator is driven
Diagnostic algorithm
- Connect a scan tool, read/record B2106 and any other codes; note ignition/key state and freeze frame data.
- Attempt to operate the horizontal forward function while observing code status and any module messages.
- Visually inspect switch and connector for damage, corrosion, bent pins, or water ingress; repair as needed.
- Verify power and ground at the switch connector: backprobe connector and measure reference voltage and ground continuity with key on. Compare to manufacturer specs.
- Operate the switch and observe output signal at switch connector (voltage change or continuity). If no change, suspect switch fault — bench-test or replace switch.
- If switch signals are correct, trace continuity from switch connector to the receiving module; repair any open/shorted wiring.
- Check the fuse(s) and any related relays supplying the circuit; replace if faulty.
- If wiring and switch are good, check the receiving module input and driver output with a scope or scan tool. Consider module replacement or reprogramming only after confirming wiring and switch are OK.
- After repairs, clear codes and retest full range of function through multiple cycles to confirm repair and ensure code does not return.
- Document findings and repaired items; if intermittent, perform extended road/operation test
Likely causes
- Switch internal contact failure (most common)
- Connector contamination / corrosion at switch or module
- Intermittent open/short in harness from motion or wear
- Failed ground or missing 5V/12V reference feed
- BCM or actuator driver failure (less common)
Fault status
Status
Horizontal Forward Switch Failed — switch circuit not responding or out of specification. Check switch, connectors, wiring and related module.
Repair difficulty: Medium
Diagnostic time: 0.3-1.5 hours
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Repair manuals
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138
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