P1626

Code

MERCURY P — Powertrain

Voltage to Vehicle Load Control Module Circuit Not Detected

Brand: MERCURY

Type: P — Powertrain

Views: UK: 31 EN: 66 RU: 37

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Page language: EN

Causes

Blown fuse or fusible link supplying the VLCM
Open or shorted power feed wiring to the VLCM
Poor or corroded battery positive or chassis ground connections
Disconnected or corroded VLCM connector terminals
Failed Vehicle Load Control Module (internal power supply fault)
Related control module (PCM/BCM) or ignition switch fault preventing feed voltage

Symptoms

Illumination of warning lamp(s) or instrument cluster messages
Certain electrical loads (accessories, lights, pumps) do not operate
Hard or no-start condition if VLCM controls starter/feed circuits
Intermittent loss of vehicle electrical functions
Stored or pending electrical DTCs and possible communication errors

What to check

Confirm stored DTC(s) and freeze frame with a scan tool
Measure battery resting voltage (engine off) and voltage with key ON, engine cranking
Visually inspect battery positive/negative terminals and ground straps for corrosion/tightness
Inspect fuses, fusible links and relays related to vehicle load control; replace if blown
Visually inspect VLCM connector and wiring for corrosion, damage, or loose pins
Backprobe VLCM power supply pin with key ON to verify presence of battery/ignition feed voltage

Signal parameters

Expected VLCM supply voltage (Key ON, Engine OFF): approximately battery voltage (~12.0–13.5 V)
Minimum acceptable during cranking: typically >9.0 V (depends on vehicle state)
Open/no-voltage condition: 0 V or significantly below battery voltage at the VLCM power pin
Intermittent fault: fluctuating voltage or loss of voltage when harness is moved
Compare measured voltage to battery terminal voltage to detect voltage drop (>0.5 V indicates possible problem)

Diagnostic algorithm

Retrieve DTC(s) and freeze-frame with a scan tool; note ignition state and battery voltage values.
Measure battery voltage and inspect battery terminals and ground connections; clean/tighten as needed.
Identify the VLCM power fuse(s)/fusible link(s) and inspect/replace if blown. Verify fuse holder and inline connections.
With key ON (engine OFF), backprobe the VLCM power supply pin and verify battery/ignition feed voltage. Record value.
If no voltage at the module pin, trace the power feed using the wiring diagram: check continuity to the fuse, the relay, and battery positive. Repair any open/shorts.
Perform voltage drop test between battery positive and VLCM power terminal while key ON and during cranking; repair high voltage drop paths.
Inspect and test grounds related to the VLCM and main chassis ground points for low resistance; repair as required.
If wiring and supply are confirmed good but the VLCM lacks voltage or reports internal supply faults, consider replacing the VLCM. Follow manufacturer procedures for replacement and reprogramming if required.
After repairs, clear codes and verify repairs by cycling ignition and road test; monitor for reoccurrence and check for additional related DTCs.

Likely causes

Blown/failed fuse or fusible link in VLCM power circuit
Loose or corroded battery terminal or chassis ground
Open power feed between battery/ignition source and VLCM connector
Corroded or bent pins at the VLCM connector
Failed VLCM or failed upstream relay/ignition feed

Fault status

⚠️ Status

Voltage to Vehicle Load Control Module circuit not detected — the module is not sensing the expected supply voltage. Inspect fuses, power feed wiring, battery/ground connections and module connector before replacing the module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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P1626 — Voltage to Vehicle Load Control Module Circuit Not Detected