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08/03/2005

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Automatic Headlight Extender for Ford Scorpio 95+

The Scorpio is a very well equipped car, especially in the Ultima variant. However it was lacking in some areas in comparison to the competition of the time. I decided to add features to the vehicle to further the equipment level. After adding Automatic Wipers and Audible indication on Lock and Unlock, the next project considered was an Automatic Headlight extender, offering the function of timed courtesy operation of the headlamps.

The idea is that if required, the headlamps remain activated when the ignition is switched off, the light from the headlamps can then be utilized to light up the drive, or add illumination in a dark street or carpark. After a short period of 30 seconds or so the lights switch off.

Additionally an optional auxiliary input can be utilized, this can turn on the headlights, when the ignition is off. One use of this is possibly in partnership with the Audible indication system (AWD), so that headlamps are turned on when the remote keyfob is activated to open the door locks.

Furthermore the project is designed to be relatively easy to construct, even for someone with very little practical experience.

The system does not affect the normal use of the headlights and is suitable for any Ford Scorpio 95+ (It may work on other models, but this has not been evaluated). Completed units are available in addition to blank PCBs.

Design
As already noted, the system should be reasonably straightforward to construct and even someone with virtually no soldering experience should be able to build the circuit up an a wet Sunday afternoon.

Secondly the system should be simple and reasonably quick to install with minimum wiring and modifications.

The circuit consists of two relays, 1 transistor, 2 resistors and 4 diodes. Under normal conditions when the ignition is on and the headlamps are on the circuit does nothing. If the headlamps are left in the 'on' position on the selector switch and then the ignition is turned off, then the selector turned to off, the headlamps will stay on for around 35 seconds.

Here is the techy bit for those who are interested. Relay RL1 is turned on if the headlamps are on and RL2 contact (NC) is off as the ignition is turned on. If the ignition is turned off the voltage at CN1 is removed as the headlamps normally turn off with the ignition switch, however RL1 is held in for 100mS by Capacitor C2, also RL1 closes as it turns off providing voltage from CN2, as RL1 is closed the voltage flows through RL1s contact to CN1 and hence holds RL1 in and provides power to the headlights.
TR1 is held on by the voltage at CN3, this is only present with ignition on. When the ignition is turned off TR1 remains conducting as C1 supplies a base current, C1 discharges to a point that RL1 switches off in around 35 seconds. Once the system has timed out RL1 opens, switching off the headlamps and completely switching off the circuit, hence no standby current is required.

Click here to download schematic in PDF format

Construction
Note, built up units are available

A ready made printed circuit board is available to interested Scorpio owners. Firstly fit the resistors, diodes (noting band), links, transistor, connectors, relays and fuse holders, then capacitors noting polarity. The PCB is designed for easy construction, but note that through hole plating has been used to reduce the possibility of failing joints due to vibrations. If you solder something in the wrong position it may be difficult to remove.

 

Quantity

Value

Farnell Part No

2

470u 16V Axial Capacitor

920-460

4

1N4004 Diode

251-707

1

BC548C Transistor

933-922

1

10K 0.25w Resistor

509-280

1

1K 0.25w Resistor

509-164

1

10A Automotive Fuse

ATO

1

1A Automotive Fuse

ATO

5

Push on 6.35m Faston pcb Connector

209-284

2

NAIS JSM1 Automotive Relay

910-351

2

Automotive Fuse Holder

ATO 581-525

I used Farnell Electronics for the parts, www.farnelll.com/uk The approximate price at the time of writing for components, excluding PCB was 3.50.

Installation
I used a small plastic case to mount the PCB into, this protects it from moisture and enables the unit to be fitted in the engine bay. The circuit could be fitted internally in the cabin area, but external fitting appears to require less wiring work through glands etc. If the unit is fitted inside the cabin, no case would be required (if the PCB could not be mechanically damaged).

The PCB has 4 M4 mounting holes, I used 4 off nylon screws and nuts to fix the board as shown, also a grommet was fitted, shown to the right.

The area I chose for installation was near the battery as shown in the following picture. In fact the box chosen could easily be fitted as shown.

TURN IGNITION FULLY OFF!

Connections need to be made from +12V ignition; I had already run an ignition live for the Auto Wipers, so I used this. The ignition live supply needs only handle 1A so thin suitably rated wire can be used. This is connected to CN3 +12V Ign on the PCB. Use suitable faston connectors to mate to the board connectors.

The wire to the Headlight circuit must be rated to carry at least 12A I used 2.5MM. On the left hand side in the engine bay, locate the headlamp connector as shown.

Remove the connector from the light, using a scotch lock or similar connector, rated for 15A, make a connection to the Violet/Orange wire. This is then ran up the wing and connected to the PCB on CN1 Dipped Light. Replace connector to light. Note you only connect to the left hand side lamp, the existing Scorpio wiring links the left and right dipped lamps.

Next Connect the ground (0V, Chassis) to CN5 GND, this wire can be thin suitably rated for 1A. If mounting the unit as shown, a connection to the ve side of the battery can be made.

Next remove FS2, check all your wiring, and make a connection to the +12V Permanent supply. If again locating near the battery, a direct connection can be made to the +12V side. Use suitably rated cable at least rated for 12A. Take GREAT CARE when connecting to the positive side not to short anything out. SERIOUS BURNS CAN RESULT FROM SHORTING.

Operation & Testing
Replace FS2 back into the fuse holder. Turn the ignition on and turn the headlamps on. Check to ensure the lights work as standard operation. Turn the ignition off and remove the key then turn off the Headlamp selector switch. The headlamps should remain on for 35 seconds then switch off. If you restart the ignition before the time period has elapsed, the lights will switch off.

Remember REPLACE Battery cover!

To defeat the operation, switch off lights before switching off ignition.

As the lights only remain on for 35 seconds after ignition is off, no battery drain problems should occur.

Advanced
The delay before switch off was set around 35 seconds, its not known if extending this delay may cause problems with the alarm activating on certain models of Scorpios. However to increase or reduce the delay time, change the value of C1.

Also provision is made for an Auxiliary input, via CN4 Aux connection. If the ignition is off and Aux is connected to ground the lights will turn on and stay on until the Aux signal is removed. One possible use is in conjunction with the Audible indication system (AWD) modifications, shown on the site. This would allow remote turning on of headlamps via the remote fob. (The AWD program would require modifications, as is, it would just flash the headlights 3 times).

Printed Circuit Boards, Components & Built up Units
PCBs are available to interested Scorpio owners.

In addition a complete kit of components is available, this gets around the minimum order quantities from many component suppliers, excluding hardware i.e. box, wire etc is NOT included.

Also completed and tested circuits are available, but no hardware is included.

Disclaimer and Legal
No warranties or guaranties are given; no responsibility for damage is taken, for use of this design. It is provided purely for DIY use and you are responsible for its use and integration. All details, circuits, etc can be freely used and modified for non-commercial purposes.
 

   
 
 

 

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