Code
P1502
HUMMER
P — Powertrain
Theft Deterrent Fuel Enable Signal Not Received
AI status
Completed
Completed
100%
Causes
- Faulty theft deterrent/immobilizer module (BCM, RFA, IP or dedicated immobilizer module)
- Open or shorted wiring/connectors between theft module and PCM
- Blown fuse or failed fuel pump/fuel enable relay
- Faulty PCM or incorrect PCM programming
- Weak battery or poor ground affecting module communications
- Intermittent key recognition (damaged key transponder or antenna)
Symptoms
- Engine cranks but will not start
- No audible fuel pump prime when key is turned to RUN
- Security/ theft indicator lamp illuminated or flashing
- No fuel pressure at the fuel rail
- Possible instrument cluster message like “Security System Active”
What to check
- Scan all modules for stored and pending codes; record freeze frame data and related codes
- Verify battery voltage is healthy (12.4V+ at rest) and ground connections are clean/tight
- Inspect fuses and fuel pump / theft deterrent relays for continuity and operation
- Listen for fuel pump prime with key in RUN; backprobe fuel pump relay control
- Check security indicator behavior during key cycle and any key recognition messages
- Check wiring and connectors between PCM and theft deterrent/BCM for corrosion, damage, or loose pins
Signal parameters
- Expected: theft-deterrent fuel-enable signal present to PCM during RUN/CRANK (either an active logic line or authorization message on vehicle data bus)
- Voltage/level: depends on vehicle design — could be a low-voltage logic line (~0–5V) or a switched 12V enable; reference vehicle wiring diagrams for pin-level values
- Timing: authorization must be present within initial cranking window; absence flagged as no fuel-enable
- Communication: if authorization is via CAN/serial data, check for valid module messages and bus health (no bus short/open)
Diagnostic algorithm
- Retrieve all DTCs from PCM and theft/BCM modules. Note time stamps and related codes.
- Verify basic electrical: battery voltage, charging system, and main grounds.
- Check fuses related to fuel pump and theft deterrent modules; replace if blown and re-test.
- Confirm fuel pump operation: backprobe pump relay coil and output while turning key to RUN; measure fuel rail pressure. If pump does not run, isolate pump circuit to determine pump vs control.
- Observe theft/security indicator during key cycles. Use a scan tool to view theft module status and any immobilizer events.
- With a scan tool, monitor the PCM input that receives the fuel-enable signal or the data bus messages that contain authorization. Compare to expected values from wiring diagrams.
- Inspect wiring/connectors between PCM and theft module for continuity, shorts to ground/power, corrosion, or damaged pins. Repair as necessary.
- Try starting with a known-good key or reprogram/learn the key per factory procedure if transponder/key recognition is suspected.
- If communication messages are missing, test the CAN/serial bus for proper termination and voltage levels; repair bus faults.
- If wiring, relays, keys and modules test good but no enable is received, consider reprogramming or replacement of the theft module or PCM following OEM procedures. Clear codes and retest after each repair step.
Likely causes
- Lost or corrupted immobilizer authorization message on the network
- Damaged/poor connector or pin at PCM or theft module causing no input
- Failed fuel pump relay or blown fuse preventing pump enable
- Dead key/transponder or antenna ring failure preventing authorization
- Battery voltage too low during cranking so module doesn't respond
Fault status
Status
Theft Deterrent Fuel Enable Signal Not Received — PCM did not detect authorization from the theft deterrent module; fuel enable not received during start attempt.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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Repair manuals
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138
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