Code
B2752
HUMMER
B — Body
Remote Keyless Entry Transmitter Battery Low
AI status
Completed
Completed
100%
Causes
- Depleted or weak key fob battery
- Poor or corroded battery contact inside the transmitter
- Incorrect battery type or incorrect installation (polarity)
- Water or impact damage to the transmitter
- Intermittent transmitter electronics fault
- Receiver/antenna or wiring issue (rare) or RF interference
Symptoms
- Reduced remote range or intermittent lock/unlock operation
- Remote functions fail occasionally or stop working entirely
- Vehicle displays a message or indicator indicating remote battery low
- Remote start or passive entry may fail or be unreliable
- May require multiple button presses or close proximity to vehicle
What to check
- Verify the exact DTC and freeze frame or event data in the body control module (BCM/RCM)
- Inspect the transmitter for physical damage, moisture intrusion, and battery contact condition
- Measure the key fob battery voltage with a multimeter while idle and while a button is pressed (if accessible)
- Try a known-good spare transmitter (if available) to confirm vehicle receiver is working
- Replace the coin cell with a fresh recommended-type battery and re-test
- Check for multiple stored remotes in vehicle and test each
Signal parameters
- Typical transmitter battery: 3.0 V coin cell (e.g., CR2032) — nominal voltage depends on fob design
- Battery low threshold (typical): battery voltage falling below ~2.5–2.8 V may trigger a low-battery flag
- Common RF carrier frequencies: 315 MHz (North America) or 433 MHz (other regions) depending on market
- Modulation types commonly used: ASK/OOK or FSK depending on transmitter design
- Expected effective range: varies by vehicle and environment; significant reduction suggests low battery or antenna problem
Diagnostic algorithm
- Retrieve B2752 and any related codes from the BCM/RCM. Note occurrence count and any freeze-frame data.
- Ask the owner to demonstrate the symptom (reduced range, intermittent operation). Attempt operation from different distances.
- Visually inspect the remote: case integrity, battery contacts, signs of corrosion or water entry.
- Open the transmitter and check battery orientation and type against the service manual. Replace with a fresh, correct battery.
- Measure new battery voltage with a multimeter before and after installing. If voltage is below expected nominal, replace again with a verified fresh cell.
- Re-test remote operation and verify increased range and consistent function. If a spare known-good remote works correctly, the fault is isolated to the original transmitter.
- Clear the DTC(s) and perform multiple remote operations to confirm the code does not return.
- If the code returns after battery replacement and the fob has good battery voltage, inspect/clean contacts and consider opening further to inspect PCB/antenna. Replace transmitter if damaged.
- If multiple remotes fail or only a new remote works intermittently, check vehicle receiver/antenna wiring and BCM for faults. Refer to manufacturer-specific procedures for receiver diagnostics or reprogramming.
- After repair or replacement, confirm all remotes are programmed and functioning, then clear codes and perform final verification.
Likely causes
- Aged/depleted coin cell (most common)
- Dirty/corroded battery contact or spring causing high resistance
- Battery installed backwards or wrong size/type
- Damaged PCB or antenna in the fob from shock/water
- Multiple low battery events flagged by BCM/RCM due to intermittent contact
Fault status
Status
Remote keyless entry transmitter battery low — replace transmitter battery and retest. If problem persists, inspect transmitter for damage or replace transmitter.
Repair difficulty: Easy
Diagnostic time: 0.25-0.5 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.
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