FAQ
TL;DR: 2 trigger wires control Focus MK1 central locking; "Lock control ... black and red, black and green (thin)" and negative-trigger. Use the correct lock wire to close; black/green is unlock. [Elektroda, CameR, post #17078416]
Why it matters: This helps Ford Focus MK1 owners and installers fix central locking that opens but won’t lock via trigger inputs.
Quick Facts
- Negative trigger inputs in the driver’s door harness: black/green = unlock, black/red = lock (thin wires). [Elektroda, CameR, post #17078416]
- Test with all doors closed so the system “sees” every door shut before accepting a lock command. [Elektroda, autoas, post #17078086]
- If one control line sits at ground, isolate and switch it using 2 SPDT relays. [Elektroda, abart64, post #17078283]
- Common cause: defective control switch inside the driver’s lock; bypass by cutting the door-side and driving the car-side. [Elektroda, Anonymous, post #17078556]
- Mechanical key still locks/unlocks even when trigger tests fail, per user report. [Elektroda, trajmund, post #17078730]
Which wires close and open the central locking on a Focus MK1?
In the driver’s door harness, use two thin wires. Black/green is the unlock trigger. Black/red is the lock trigger. The system expects negative (ground) pulses. “Lock control … black and red, black and green (thin).” [Elektroda, CameR, post #17078416]
Why does grounding a wire open but not close the locks?
A failed driver’s lock control switch can leave the lock input stuck or ignored. That is a standard Ford fault. Cut the control wires in the door loom and command the car-side directly. “Defective control switch in the lock.” [Elektroda, Anonymous, post #17078556]
Do I need all doors closed when testing lock triggers?
Yes. The system must see all door-ajar switches closed. Otherwise it may ignore the close command. “Do these attempts on all closed doors.” Close every door, then pulse the chosen wire to test. [Elektroda, autoas, post #17078086]
How do I connect an aftermarket keyless or alarm to this Focus?
Tap the two thin trigger wires in the driver’s door harness. Send momentary ground pulses to command lock and unlock. Black/red closes. Black/green opens. Secure connections and avoid holding ground to prevent unintended cycling. [Elektroda, CameR, post #17078416]
How do I wire relays if one trigger line has constant ground?
Use two SPDT relays to isolate the vehicle from the faulty door-side. 1. Cut both trigger wires near the door. 2. Connect controller outputs to relay coils and contacts. 3. Feed momentary ground from relays to the car-side lock and unlock wires. This 2‑relay method prevents backfeeding. [Elektroda, abart64, post #17078283]
Could the comfort module be bad if lock won’t close via trigger?
It’s less likely if the car locks and unlocks with the key. That proves the module responds. The common failure is the driver’s lock switch. Bypass it by cutting door-side wires and driving the car-side. “Standard fault in Ford cars.” [Elektroda, Anonymous, post #17078556]
My loom doesn’t show black/red; any alternate lock color to check?
Some versions reportedly present black/orange as the lock signal. Verify with a test light before connecting. If colors vary, trace from the driver’s lock connector to the A‑pillar to confirm function. [Elektroda, abart64, post #17078283]
Is the Focus MK1 central locking negative or positive trigger?
It uses negative (ground) triggers for both lock and unlock. Apply a brief ground pulse to the respective wire. The original note states “downside control.” [Elektroda, CameR, post #17078416]
Grounding black/green unlocks, but nothing will lock—what next?
Close every door and retry. If lock still won’t respond, the driver’s lock switch is likely faulty. Cut the two control wires at the door and command the car-side directly from your controller or relays. [Elektroda, Anonymous, post #17078556]
Where exactly should I tap the wires—door or A‑pillar?
Tap in the harness to the driver’s door. Access is convenient at the A‑pillar boot or inside the door. Identify the thin black/red (lock) and black/green (unlock) before making connections. [Elektroda, CameR, post #17078416]
Why does the key still lock/unlock when trigger tests fail?
Users report the mechanical key still operates central locking even when manual grounding fails. That suggests the module and actuators work, and the issue lies in the door-side switching path. [Elektroda, trajmund, post #17078730]
I’ve tried many wires; could I be on the wrong cable?
Yes. Verify you are on the correct pair in the driver’s door harness. “You’re probably on the wrong cable.” Follow the thin black/green and black/red leads before committing connections. [Elektroda, CameR, post #17078072]
