Code
P1626
BUICK
P — Powertrain
Theft Deterrent Fuel Enable Signal Lost
Views:
UK: 19
EN: 59
RU: 21
AI status
Completed
Completed
100%
Causes
- Failed or misconfigured immobilizer/theft deterrent module (BCM, RCDLR, passkey module)
- Open/short/intermittent wiring or poor connector between theft module and PCM/ECM
- Blown fuse(s) or faulty fuel pump/fuel enable relay
- Unprogrammed, damaged, or non‑recognized key/transponder
- PCM/ECM internal fault or corrupted software
- Low battery voltage or intermittent power supply to immobilizer or PCM
Symptoms
- Engine cranks but will not start (no fuel)
- Fuel pump does not prime when key turned ON
- No injector pulse or fuel enable PID reported by scan tool
- Security/immobilizer warning light or DIC message on instrument cluster
- Intermittent no‑start or starts only with a spare/key reprogram
What to check
- Retrieve all DTCs from PCM/ECM and theft deterrent/BCM; note freeze frame and occurrence count
- Verify battery voltage is within specification before and during cranking
- Check for security/immobilizer indicator behavior when inserting/turning key
- Verify fuel pump operation and fuel pressure when attempting start
- Use a scan tool to monitor a Fuel Enable, Injector Enable, or Theft Status PID while turning ignition to ON/START
- Inspect relevant fuses and relays (immobilizer, PCM, fuel pump relay) and verify relay operation
Signal parameters
- Fuel enable is a digital enable/inhibit signal or a network message — should be active when ignition is ON/START and the key is recognized
- Expected live data: Fuel_Enable = ON (true) during cranking/start when immobilizer permits fuel
- Voltage on enable circuit: typically near battery voltage when active, near 0V when disabled (verify with vehicle wiring diagram)
- If message-based, check CAN/Class 2 frames for Theft/Immobilizer status and PCM receipt
- Use oscilloscope to confirm steady/high (or expected waveform) on the enable line during crank
Diagnostic algorithm
- Read and record all DTCs from PCM and theft deterrent/BCM; clear codes and attempt to recreate. 2) Verify battery voltage >= specification and good ground connections. 3) Observe security lamp and attempt start with known-good programmed key; try spare key. 4) Using a scan tool, monitor Fuel Enable / Theft Status PIDs while turning ignition to ON and cranking to confirm PCM is not receiving enable. 5) Check fuses and operate/test fuel pump relay; apply battery to relay coil/socket to confirm pump runs. 6) Backprobe the fuel‑enable circuit at the PCM and theft module while a helper turns the key to START; check for expected voltage/signal or bus message. 7) If no enable signal, trace wiring continuity between PCM and theft module; repair open/shorts or connector corrosion. 8) Check BCM/theft module for other DTCs and perform module self-tests; if module has lost programming, reprogram or relearn keys per factory procedure. 9) If wiring and theft module OK but PCM still reports lost signal, consider PCM software update or PCM replacement as directed by manufacturer service information. 10) After repair, erase codes and verify repeatability and normal operation (fuel enable present, engine starts, no security warnings).
Likely causes
- Damaged/loose connector at theft deterrent module or PCM
- Corroded wiring or chafed harness near firewall or steering column
- Faulty fuel pump relay controlled by immobilizer signal
- Key transponder not programmed or faulty key
- Fault stored in BCM or PCM requiring reprogramming or replacement
Fault status
Status
Theft Deterrent Fuel Enable Signal Lost
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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