Code
B1845
HUMMER
B — Body
Driver Lumbar Down Switch Circuit Malfunction
AI status
Completed
Completed
100%
Causes
- Open or short in the lumbar down switch wiring
- Corroded or loose connector at the switch or seat control module
- Failed lumbar down switch (internal contact wear or contamination)
- Faulty seat control module or internal driver seat control electronics
- Blown fuse or poor power/ground to the seat control circuit
- Intermittent connection due to broken wires inside the seat harness (pinch points)
Symptoms
- Driver lumbar will not move down (no response when button pressed)
- Intermittent lumbar down operation (works sometimes, then not)
- Seat adjustment works for other functions but lumbar down does not
- DTC stored and possible MIL/indicator depending on vehicle configuration
What to check
- Read and record stored DTCs and freeze-frame data with a scan tool
- Attempt operation of lumbar down while monitoring live data for switch state
- Visually inspect switch and harness at the seat for damage, corrosion, or loose connectors
- Check seat module fuses and battery supply to the seat control circuit
- Perform wiggle test on harness while observing live data for intermittent faults
- Measure voltage at the switch connector (reference, supply, and ground) and check continuity to the seat module
Signal parameters
- Supply voltage to seat module: ~9–14 V (battery voltage when ignition on)
- Logic/reference signal for switch (varies by model): typically 0–5 V — 0 V or near 0 V when closed to ground, open/near reference when released
- Closed switch continuity: < 2 ohms (near short)
- Open switch continuity: OL / infinite
- Intermittent or fluctuating voltage indicates poor connection or short
Diagnostic algorithm
- Connect a scan tool, read and record codes and any related seat/body codes. Verify condition is repeatable.
- With ignition ON (or as specified), operate lumbar down switch while monitoring live data for the switch input state. Note if the module sees the press.
- Visually inspect the driver lumbar switch, its connector, and the seat wiring for damage, corrosion, pinched areas, or loose terminals. Repair visible damage.
- Check related fuses and ensure the seat control module has battery power and a good ground.
- Backprobe the switch connector. Verify reference/supply voltage and ground presence. Measure the switch signal while pressing the button. Compare to expected signal params.
- If no proper signal at the switch, trace wiring back to the seat module and check for continuity and shorts to ground/power. Repair any wiring faults.
- If the switch shows correct function at the connector but the module does not register it, test continuity between the switch and module pins. If wiring is good, suspect seat control module failure.
- Optional: bench-test or temporarily replace the lumbar switch (or use a known-good switch) to confirm a defective switch.
- After repair or replacement, clear codes and verify proper operation and that the DTC does not return after several cycles.
Likely causes
- Broken/shorted wire in the seat harness near the seat base or door hinge
- Contaminated or bent switch terminals at the lumbar down switch
- Connector corrosion at the seat switch or seat module
- Failed lumbar down switch (most common for a single-button failure)
Fault status
Status
B1845 - Driver Lumbar Down Switch Circuit Malfunction. Detected open, short, incorrect voltage, or intermittent signal on the driver lumbar down switch input to the seat control module.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
-
HUMMER: 2009
-
HUMMER: 2008
-
HUMMER: 2007
-
HUMMER: 2005
-
HUMMER: 2004
-
HUMMER: 2000
-
HUMMER: 1999
-
HUMMER: 1994
-
HUMMER: 1993
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
B1845
Other
B — Body
Ignition Tamper Circuit Failure
AI status
Completed
Completed
100%
Causes
- Open or short in the lumbar down switch wiring
- Corroded or loose connector at the switch or seat control module
- Failed lumbar down switch (internal contact wear or contamination)
- Faulty seat control module or internal driver seat control electronics
- Blown fuse or poor power/ground to the seat control circuit
- Intermittent connection due to broken wires inside the seat harness (pinch points)
Symptoms
- Driver lumbar will not move down (no response when button pressed)
- Intermittent lumbar down operation (works sometimes, then not)
- Seat adjustment works for other functions but lumbar down does not
- DTC stored and possible MIL/indicator depending on vehicle configuration
What to check
- Read and record stored DTCs and freeze-frame data with a scan tool
- Attempt operation of lumbar down while monitoring live data for switch state
- Visually inspect switch and harness at the seat for damage, corrosion, or loose connectors
- Check seat module fuses and battery supply to the seat control circuit
- Perform wiggle test on harness while observing live data for intermittent faults
- Measure voltage at the switch connector (reference, supply, and ground) and check continuity to the seat module
Signal parameters
- Supply voltage to seat module: ~9–14 V (battery voltage when ignition on)
- Logic/reference signal for switch (varies by model): typically 0–5 V — 0 V or near 0 V when closed to ground, open/near reference when released
- Closed switch continuity: < 2 ohms (near short)
- Open switch continuity: OL / infinite
- Intermittent or fluctuating voltage indicates poor connection or short
Diagnostic algorithm
- Connect a scan tool, read and record codes and any related seat/body codes. Verify condition is repeatable.
- With ignition ON (or as specified), operate lumbar down switch while monitoring live data for the switch input state. Note if the module sees the press.
- Visually inspect the driver lumbar switch, its connector, and the seat wiring for damage, corrosion, pinched areas, or loose terminals. Repair visible damage.
- Check related fuses and ensure the seat control module has battery power and a good ground.
- Backprobe the switch connector. Verify reference/supply voltage and ground presence. Measure the switch signal while pressing the button. Compare to expected signal params.
- If no proper signal at the switch, trace wiring back to the seat module and check for continuity and shorts to ground/power. Repair any wiring faults.
- If the switch shows correct function at the connector but the module does not register it, test continuity between the switch and module pins. If wiring is good, suspect seat control module failure.
- Optional: bench-test or temporarily replace the lumbar switch (or use a known-good switch) to confirm a defective switch.
- After repair or replacement, clear codes and verify proper operation and that the DTC does not return after several cycles.
Likely causes
- Broken/shorted wire in the seat harness near the seat base or door hinge
- Contaminated or bent switch terminals at the lumbar down switch
- Connector corrosion at the seat switch or seat module
- Failed lumbar down switch (most common for a single-button failure)
Fault status
Status
B1845 - Driver Lumbar Down Switch Circuit Malfunction. Detected open, short, incorrect voltage, or intermittent signal on the driver lumbar down switch input to the seat control module.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
Similar codes
Repair manuals
Brands with available manuals
6,965
The library contains 6,965 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email