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  Flash-on-Lock Mod

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Flash-on-Lock Mod


Indicator Flash-on-Lock


On the Ford Scorpio various central locking configurations are available dependent on country of sale.  Most UK variants will either not flash on lock or flash a short delay after deadlocking, if ultrasonic sensors are fitted.  In many cases an FMD can reprogram them using WDS for a charge, but some early models cannot be programmed in this way.  Additionally no audible feedback is available.

 For this reason a small circuit was developed to emulate the flashing indicators on other manufacturers' models.  The modification is small and simple to install.  It provides an on off single flash with a duration of around 0.5 seconds when the doors are locked, provided the ignition is off.  Only one flash is provided and no second confirmation of double locking, as this is usually provided.  A sounder can also be fitted to provide an audible indication of locking.



The design is simple and, unlike some of the other projects I developed for the Scorpio, does not have a microcontroller. In fact it has only a few components.  The design reflects a low cost approach with such things as ATO fuse holders and fuses replaced with 20mm fuses, with direct wiring rather than terminals.

With reference to the schematic diagram (Acrobat required), when the ignition is off and the doors are locked a 12V level is applied to CN1, as Capacitor C2 is discharged previous to this point by Resistor R2, a current flows through C2 and the coil of relay RL1, causing RL1 to close introducing a supply to the indicators and the sounder (AWD) via the associated blocking diodes, this current rapidly drops as C2 charges up, at a point of around 0.5 seconds after the locking signal appearing, RL1 opens as insufficient current flows to develop its holding voltage.  If the ignition were to on, RL1 would not close when the doors locked, as C2 would be previously charged via R1 and D2.

R2 rapidly discharges C2 when the lock signal or ignition signal is removed, hence ďresettingĒ the circuit for the next lock operation.



The eight wires are shown in the table, YELLOW & BLUE are optional and are for a sounder (12Vdc max 300mA).  Splice and extend the wires as required, either with butt splices, scotch locks or solder and tape method.  (Noting that Scotch Lock type connectors must be sized correctly for the wire diameter and fitted correctly).  Insulate all connections including the sounder wires if not used.









Permanent supply from Battery



Chassis / 0V



Central Locking Lock Wire

+12V IGN


+12V Supply with Ignition On



Direct Connection to Indicator



Direct Connection to Indicator

*AWD +


+12V out to Sounder



Sounder GND




*Sounder Optional










Above table shows the wires coming from the Flash on Lock unit.

RED is Permanent +12V from the battery and this supply can be found on the rear of the DLC connector.  The driverís dash area that contains the Coin Box can be dissembled by removing 4 screws.  Two from the side and two from inside the Coin Box.  This wire should be Orange and on pin 16 of the connector (DLC-OBD2).  Or connect to a suitable +12V Permanent supply point, if one is already available. 

BLACK is 0V (Chassis Ground), the screw that mounts the Wood Effect dash area at the top of the drivers side lower dash area can be easily utilised as a Ground, use a suitable circular crimp lug.  Or connect to a suitable GND if one is already available.

GREEN is the connection to the Central Locking Lock signal; it is easy to locate on the front passenger side.  Remove the pull off plastic cover bottom left in the passenger well.  Then remove the sound deadening felt to reveal wiring loom.  The Yellow/Blue wire is the required signal, use a scotch lock or similar to connect to this wire.  Ensure you connect to the correct wire.  (This wire is also used on the Lock on Go unit)

BROWN is the Ignition +12V supply; this can be connected to the Key On (Position 2) ignition switch wire.  The driverís dash area that contains the Coin Box can be dissembled by removing 4 screws.  Two from the side and two from inside the Coin Box.  Locate the wires from the ignition switch and follow down to an inline connector.  The smaller diameter green wire can be connected to using a scotch lock or similar. This signal stops the system flashing the indicators when the ignition is on and the doors are locked.

Or connect to a suitable Ignition +12V if one is already available.

PINK This connection can be made in the engine bay at the Left Hand Indicator; itís the Blue/Orange wire coming from the indicator.

VIOLET This connection can be made in the engine bay at the Right Hand Indicator, itís the Blue wire coming from the indicator.

When you have completed and checked the installation, you are ready to test the system.  Simply lock the doors with ignition off and the indicators and sounder (when fitted) should operate.

This device can be purchased from James Austin M.I.E.E. 

Mail him on: James Austin

Before use please read the notice below:


Disclaimer and Legal

If you use this design, in doing so you are acknowledging your agreement with the following.

No warranties or guaranties are given; no responsibility for damage is taken, for use of this design.  No responsibility is taken for direct, consequential or incidental damages or losses. It is provided purely for diy use and you are responsible for its use and integration.  All details can be freely used and modified for non-commercial purposes.

This is not a fail-safe design; incorrect installation or a failure may cause Indicator lamp(s) to operate.





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