Headlamp Dipping using Headlamp Flash Switch by Derek Harris
This modification was done on my Shadow II SRH31074. However, the principle applies to all Crewe Cars
Post 65 Shadow/T type and SZ type prior to VIN12000.
The change involves using existing wiring and components and adding two new components: a Dipping
Relay (DR) controlled by a Latching (or sequencing) Relay (LR).
Parts Needed
1.
2.
3.
4.
Latching Relay(LR): Durite 0-728-02 http://www.mellorautoelectrical.co.uk/ Tel: 01924-274774
Dipping Relay (DR): Durite 0-728-12. Any Parts store, Holden, or Mellor
4-way snap connector (SC). Snap connectors (SCS) and Blue crimp blade terminals (BCBT)
Some Black Wire, Red Wire, Blue/White Wire, Blue/Red Wire, Green Wire
Operations
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Remove cover above foot pedals and around handbrake and bonnet opener
Remove overrug, carpet and underlay from driver’s footwell
Undo 2 x 2BA setscrews holding floor dipswitch. Unplug floor dipswitch.
Replace 2 x 2BA set screws to seal holes.
Note that the female plug socket (FPS)
4.1. has three wires leading to it: U Blue (12v + when Ignition On and Lamp Switch on),
UW Blue/White (Main Beam), UR Blue/Red (Dip Beam).
4.2. takes normal classic snap connectors (SCS)
Decide where to place the two new relays. Mine are tucked up with the wires between the
steering column and bulkhead.
Replace 2 x 2BA set screws to seal holes.
Need Ignition On power source + (IO+ ) for Latching Relay LR and on to DR. This can either
come from the UG Blue/Green from Fuse 7 to the Headlight Flasher Relay, or the GS Green/
Slate from Fuse 20 to the Radio which can be connected near the separate Radio Fuse. I did
the latter. See Wiring Diagram page 3, “8”.
7.1. Make up Wires
7.1.1. 1 x Green as in 8 above with SCS at on end to go in a 4 way Snap Connector SC
7.1.2. 2 x Green with SCS one end and BCBT at other. To go to SC to LR30, LR56
Make up wires. See Wiring Diagram page 3, “6”.
8.1. 1 x Blue with one end SC the other BCBT For connecting FPS Blue to Power+ on DR
8.2. 1 x Black Wire with BCBT one end and Round Earth Terminal at other for DR86
8.3. 1 x Red Wire with BCBT both ends. LR56a to DR85
8.4. 1 x Blue/White or other Wire for Main Beam with one end SCS, one end BSBT DR87.
8.5. 1 x Blue/Red or other Wire for Dip Beam with one end SC, one end BSBT DR87a.
8.6. 1 x Blue/Black with BSBT one end and enough length to connect to LRS from Headlamp
Flash Switch
Connect to Headlamp Flash Switch (HFS)
9.1. Find Blue/Black wire to split and connect. If you can get there you may find it low down
behind steering column. I found it easier to undo the four screws holding the cover
behind the steering wheel. Remove the upper and twist the lower for access.
9.2. Cut Blue/Black wire and attach 1 x Blue/Black with BSBT one end and enough length to
connect to LR “S” from Headlamp Flash Switch (HFS)
Connect to Relays as shown in next two pages
Test
Replace items removed in Operation 1 & 2 above
Page 1
Headlamp Dipping using Headlamp Flash Switch by Derek Harris
LR = Latching Relay (Sequential Relay)
DR Headlamp Dipping Relay
Durite 0-728-02
Durite 0-728-12
From FPS
1.
2.
3.
U = Blue from Light Switch to DR30
to supply power to Dip and Main
UW = Blue/White to Main to DR87
UR = Blue/Red to Dip to DR87a
Flasher Switch
4.
UB = Blue/Black to Flasher Relay and to S
on LR (earth switch on)
New Wire
5.
6.
7.
8.
Green from Fuse 7 or Fuse 20 to 4 way Snap
Connector (SC)
2 x Green from SC to LR30, LR56
B = Black Earth to DR86
R = Red LR56b to DR85
to Switch DR to Main Beam
Page 2
Headlamp Dipping using Headlamp Flash Switch by Derek Harris
Wiring Diagram for Dipping from Headlamp Flasher Switch
Items
1. Rear Fog Relay connection
2. Headlights
3. Main Beam Warning Light
4. Headlamp Flash/Dipping Switch FDWD
5. Headlamp Safety Relay
6. New Headlamp Dipping Relay DR
7. Headlamp Flash Relay FR
8. New Headlamp latching (sequencing) relay LR
Colours
B
Black Y
Yellow S
Slate N
G
P
Brown Green Purple R
LG
W
Red
Light Green
White
O
U
Orange
Blue
Wires from Headlamp Flasher Dip/Windscreen Washer/Direction Indicator FDWD
UB
Blue/Black to “S” LR and “7” FR
GB Green/Blue to Washer Relay
B
Black to Horn Relay
GW
Green/White to DI RH
GR
Green/Red to DI LH
Page 3