B2700

Code

HUMMER B — Body

Ignition Shift Interlock Circuit (base number)

Brand: HUMMER

Type: B — Body

Views: UK: 15 EN: 26 RU: 15

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Page language: EN

Causes

Blown fuse or faulty relay feeding the shift interlock circuit
Open, shorted, or damaged wiring between shift interlock solenoid and control module
Corroded or loose connector(s) at the solenoid, BCM/IPC or harness splice
Faulty shift interlock solenoid (mechanical or coil failure)
Faulty body control module (BCM) / instrument panel cluster (IPC) output or software issue
Defective ignition switch or brake pedal switch that provides the release condition signal

Symptoms

Cannot shift out of Park or release shifter without override
Key may be stuck in ignition or ignition removal interlocked
Shift‑interlock warning or message on dash (if equipped)
Intermittent ability to shift out of Park
No audible click from interlock solenoid when command given

What to check

Scan vehicle for additional stored codes and freeze frame data; note ignition/key and brake pedal status when code set
Visually inspect fuses and relays for the shift interlock circuit
Visually inspect wiring and connectors for damage, corrosion, or poor mating at solenoid and BCM/IPC
Verify brake light switch operation (brake pedal) and related fusing—if brake switch fails it can prevent interlock release
Attempt to actuate the interlock and listen for solenoid operation, or use a scan tool to command the interlock if supported
Measure voltage at the solenoid connector while commanding the interlock and with ignition on

Signal parameters

Battery voltage supply to circuit: ~11–14 V (key ON)
Commanded control voltage at solenoid when activated: typically ~11–14 V (or pulled to ground depending on design)
Solenoid coil resistance (typical/model-dependent): approximately 5–50 Ω (refer to service data for exact value)
Current draw when energized (typical): generally
Brake switch output: closed or supplying 12 V to interlock control input when pedal depressed (design dependent)

Diagnostic algorithm

Retrieve and record B2700 and any related codes; note conditions when code set (key position, brake applied, gear)
Inspect relevant fuses/relays and replace any blown fuses; retest
Perform a visual inspection of interlock solenoid, wiring harness, and connectors for damage, corrosion or loose pins; repair as necessary
Verify brake pedal switch operation (check that brake lights illuminate and switch changes state) and test ignition switch function if required
Using a digital multimeter, measure supply voltage and ground at the interlock solenoid connector with ignition/key in required position; record values
If safe, apply battery voltage directly to the solenoid (bench or vehicle) to confirm mechanical movement; observe current draw for abnormalities
If voltage/ground present but solenoid not actuating, measure coil resistance and compare with specification; replace solenoid if out of range or mechanically seized
If solenoid and wiring check good but no command signal from BCM/IPC, verify module outputs with a scan tool (command the solenoid) and inspect module grounds and power feeds; repair or replace module per manufacturer procedures
After repairs, clear codes, verify proper interlock operation under all required conditions, and perform a road/functional test to confirm code does not return

Likely causes

Faulty or seized shift interlock solenoid
Damaged wiring/connector at the solenoid or BCM
Blown fuse or poor ground in interlock circuit
Brake switch not signalling (prevents release)
Intermittent BCM output or internal module failure

Fault status

⚠️ Status

DTC B2700 stored: Ignition Shift Interlock Circuit — indicates an electrical or functional fault in the shift interlock system. May prevent shifting out of Park. Further diagnosis required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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B2700 — Ignition Shift Interlock Circuit (base number)