I used a Durite push on, push off switch no. 0-484-50, for the hazard warning switch from AGM Complete Parts & Components Solutions Ltd. This was installed on the dashboard edge, using a small bracket located near the steering column. Wire and terminals were from Vehicle Wiring Products Ltd.
Late TDs and the TF were fitted with a Lucas DB10 relay No. 33117. This relay substitutes the brake lamps with direction indicators on the side which is indicating, using the original rear brake lamps as indicators. It was probably wired this way to accommodate the current taken by the tungsten bulbs available at the time and to save wire. Now that the low current LED bulbs are easily obtained, a relay is not necessary. To use the relay and the original lamps would be a drain on the battery in hazard mode, as the relay takes about 1.5 amps per side. Using LEDs, the brake lamps can be switched from the brake lamp switch and the indicators directly from the dashpot indicators switch under the dashboard. The Lucas relay is not now used.
Many years ago, I restored my TD to original specification, retaining the Lucas relay and tungsten lamps; now, to install a hazard warning and to avoid complication, there is a need to update. To do this I will convert to LED lighting, not use the Lucas relay, and install new rear indicator lamps. An LED flasher unit will be necessary.
The brake lamps
To separate the brake lamps wiring from the direction indicator wiring, disconnect the wire from relay terminal no. 5 (green with purple) and join it with the wires removed from terminals 3 (white with purple), and 7 (white with brown). The brake lamps are now operated only by the brake light switch.
The rear indicators
Two extra wires are installed from the 33117relay location, to the new rear LH and RH direction indicator lamp units. Disconnect the wires from relay terminals 2 and 4 and connect these to the new feed to the LH rear indicator lamp. Disconnect the wires from relay terminals 6 and 8 and connect these to the feed to the new RH indicator lamp.
Remove the 12 feed to the indicator switch pole under the dash. This is from the main loom wiring and should be insulated. The L and R connections should remain.
Flasher unit connections:
Supply……………X Earth ………………E, or 31
Warning lamp……P Flasher out………….L
The Durite switch
The red indicator on the Durite switch has a screw thread. Make sure that this is screwed fully in.
The switch routes a 12v ignition feed to the flasher unit, but when operated it uses a direct battery feed. Referring to the Durite switch diagram…
For the 12v ignition circuit feed, disconnect the green wire at the flasher unit X (this is from the fuse A4) and extend to the Durite switch pin 1.
For the battery feed, extend from fuse terminal A2 to the Durite switch pin 2.
When operated, battery volts are fed to operate the flasher unit via pin 3.
When not operated, the original 12v feed from the ignition circuit, only, operates the flasher unit via pin 4.
Durite switch connections
Durite pin 1 fed from 12v ignition feed (green wire removed from flasher unit X).
Durite pin 2 fed from 12v from battery fuse A2.
Durite pin 3 (12v to flasher unit X, green) and to pin 4.
Durite pin 4 from pin 3.
Take the output from the flasher unit L and extend to Durite pin 5.
Durite pin 5 further extended to the direction indicator switch pole.
Durite pin 6 to the LH indicator switch terminal.
Durite pin 7 to the RH indicator switch terminal.
Picture shows the Durite switch in-stalled in a TD. The small indicator next to it is a low oil pressure warning not yet connected.
The wiring diagram shows the wiring changes for the direction indicators in blue ink and those for the brake lights in red; also, the output of the flasher unit connected to the direction signal switch pole.