Code
B1983
HUMMER
B — Body
Device Power Circuit Low
AI status
Completed
Completed
100%
Causes
- Weak or discharged battery
- Corroded or loose battery terminals
- Open or blown fuse / fusible link in device supply
- Damaged wiring (open, high resistance) in power feed or ground
- Poor or intermittent ground connection
- Short to ground or high current draw from the device
Symptoms
- Associated device(s) do not operate or operate intermittently (lights, seat, mirror, door module, etc.)
- Illuminated warning or message related to the affected system
- Multiple body/control modules reporting communication or power faults
- Stored B1983 (and possibly related codes) in module memory
What to check
- Read freeze frame and DTC history — confirm B1983 and related codes
- Check battery state-of-charge and cranking/resting voltage (should be ~12.4–12.8 V at rest, ~13.5–14.5 V with engine running)
- Inspect battery terminals and ground straps for corrosion and tightness
- Visually inspect fuses, fusible links and fuse block for damage; test continuity
- Inspect wiring and connectors for the affected device for corrosion, pin damage, or water intrusion
- Backprobe device power and ground pins and measure voltage while operating the device
Signal parameters
- Nominal battery voltage (key ON, engine OFF): ~12.4–12.8 V
- Charging system voltage (engine running): ~13.5–14.5 V
- Voltage measured at device power pin under load: should remain within ~1 V of battery/charging voltage
- Voltage drop to watch for: >1 V drop between battery positive and device power pin indicates wiring/fuse/connection problem
- Ground resistance: typically
- Device current draw: varies by device; unexpected high current suggests internal short
Diagnostic algorithm
- Verify the code: connect scan tool, retrieve B1983 and any related codes, note freeze-frame data and occurrence conditions (key ON, engine running, after cranking).
- Check battery and charging: test battery voltage and health; charge or replace if low. Verify alternator output with engine running.
- Inspect power distribution: locate and inspect fuses/fusible links for the affected circuit; replace suspect fuses and retest.
- Visual harness inspection: inspect wiring from the power source/BCM to the affected device for abrasion, breaks, chewed wires, or water ingress at connectors.
- Measure at the device: backprobe the device power pin and ground; measure voltage with the device commanded ON and during fault conditions to replicate low-voltage reading.
- Check voltage at module: if device power is supplied from a module (BCM), measure voltage at the module output pin; compare to battery voltage to isolate wiring vs module issue.
- Check grounds: measure continuity and resistance between device ground and battery negative; clean and tighten ground connections as needed.
- Isolate the load: disconnect the affected device and monitor if the low-voltage condition clears; if it does, suspect the device as a load/short.
- Wiggle and load testing: with the device connected and powered, wiggle connectors/harness while monitoring voltage to locate intermittent faults.
- If wiring and device check good, suspect module fault: verify module power inputs and outputs, update software if applicable, and consider module bench test or replacement per OEM procedures.
- Clear DTCs and retest: after repairs, clear codes and perform functional test cycles to confirm the fault does not return.
Likely causes
- Blown fuse for the affected device circuit
- Loose or corroded battery terminal or ground strap
- High-resistance splice/connector in the feed to the device
- Device internal short causing voltage drop
- Intermittent connector contact caused by moisture or damage
Fault status
Status
Device Power Circuit Low — the module detected low supply voltage to a device circuit. Verify battery, fuses, wiring, grounds and device for low-voltage condition.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Repair manuals
Manual library for HUMMER
138
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