Code
B2484
HUMMER
B — Body
Global Positioning System (GPS) Antenna Circuit
AI status
Completed
Completed
100%
Causes
- Open or shorted antenna feed/center conductor
- Corroded, loose or water-damaged GPS antenna connector
- Failed/shorted active (powered) GPS antenna or internal amplifier
- Broken or damaged coaxial cable between antenna and module
- Poor chassis or signal ground at antenna/module
- Faulty GPS receiver/module or harness connector
Symptoms
- No satellite lock or very long time-to-first-fix (TTFF)
- Navigation system shows incorrect or missing vehicle position
- Telematics features requiring GPS (e.g., OnStar-style services) inoperative or reporting location errors
- GPS-related diagnostics/warning message in infotainment or vehicle message center
- Intermittent GPS function — works sometimes and fails other times
What to check
- Scan for current and pending codes with a capable scan tool and record freeze frame/data
- Visually inspect GPS antenna, roof mounting, connector(s) and cable for damage, corrosion, or water entry
- Check for aftermarket antenna/radio installations that may have altered the original coax or connectors
- Backprobe antenna power feed at antenna connector (with harness connected) with ignition ON and observe voltage
- Check continuity of coax center conductor and shield between antenna and module with connectors disconnected
- Inspect antenna mounting for loose fasteners, crushed cable or pinched sections
Signal parameters
- Antenna power feed (if active antenna used): typically about 3–5 V DC with ignition/accessory ON (verify exact spec on vehicle wiring diagram)
- Coax center conductor continuity: low ohms between antenna center pin and module center pin; open indicates broken cable
- Coax shield continuity: continuity between antenna shield and chassis ground; short between center and shield indicates coax short
- Resistance from antenna feed to ground: should not be a short to ground (near 0 Ω)
- CAN/LIN/serial data: GPS location messages should be present on the appropriate bus when module is operating (verify with scope/scan tool)
- Intermittent symptom: voltage or RF signal may appear/disappear when connector or cable is moved
Diagnostic algorithm
- Retrieve and record B2484 and any other stored codes, then clear codes and reproduce symptom
- Perform a visual inspection of antenna, cable routing, roof pass-through and module connector for damage, corrosion, or moisture
- With ignition ON, measure antenna power feed voltage at the antenna connector (backprobe) and compare to wiring diagram specification — no voltage suggests supply/fuse/PWM driver or wiring fault
- Check continuity of the coaxial feed between the antenna and the GPS module; repair or replace if open or shorted
- If coax continuity is good and power is present, swap/replace the antenna with a known-good unit or bench-test antenna to confirm whether the antenna’s internal amplifier has failed
- Inspect and test ground at the GPS module; repair poor grounds and re-check operation
- If wiring and antenna check good, test/replace the GPS receiver/telematics/infotainment module or consult module bench-test procedures — check for software updates or reprogramming that address GPS faults
- After repairs, clear codes and verify GPS acquires satellites and the DTC does not return; road-test and re-scan to confirm repair
Likely causes
- Damaged or pinched coaxial cable (open or short)
- Corrosion/water intrusion at roof antenna base or connector
- Failed active antenna amplifier (no supply voltage or internal short)
- Loose/cracked connector at antenna or module
- Connector pins pushed back or bent
- Failed GPS receiver/module
Fault status
Status
GPS antenna circuit fault detected — open/short/high resistance or poor connection between antenna and GPS receiver; may cause loss of satellite lock or inaccurate position.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Repair manuals
Manual library for HUMMER
138
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