Solution Graphics

Part No

Terminal Layout

Power rating (Watts)


Nett Price GBP View/Buy Link


31 : ground


12v Direction Indicator Flasher 3 Pin Thermally  operated  for Kit Car builders and older vehicles
21W  x 4 + (2 x 5W) /21w x 2 + (5W)



31 : ground


12v  Direction Indicator Flasher 3 Pin ElectronicUnit
21W  x 4 + (2 x 5W) /21W x 2 + (5W)





12v Electronic   Direction Indicator Flasher Unit
21W  x 4 + (2 x 5W) / 21W x 2 + (5W)




12v Electronic   Direction Indicator Flasher Unit with dash warning light output
21W  x 4 + (2 x 5W)/ 21W x 2 +(5W)




12v Heavy Duty Electronic Flasher Relay.

21W x 6 + (2 x 5W) / 21W x (2 + 1) + (5W)




special order

Hazard Switch with built in 12v relay. Connect to left and right indicator lamp circuits to add hazard warning function.


Direction Indicator Relay Description

Direction indicators must flash at a rate of 60 to 120 Flashes per minute to comply with UK marking and lighting regulations.

Terminal Designation in accordance with DIN 72 552

31 Common ground return line to Negative battery terminal

49 Supply Input (12v)

49a Output  of first turn signal circuit (to indicator switch)

49b Output of second turn signal circuit

49c Output of third turn signal circuit

C  First indicator (dash) light

C2  Second indicator (dash) light

Typical Circuit Description

Power is supplied from ignition circuit to terminal 49 of the flasher relay via a fuse.
The output terminal 49a is wired to the centre pole of the turn signal on/off/on switch.
upon activating the direction indicator switch in either direction power is then supplied to the turn signal lamps  through the lamp filaments to ground return completing the circuit .
The load of the flasher lamps is sensed by the flasher control unit causing it to switch on / off successively and the turn signal lamps to flash at between 60 and 120 times per minute.

Direction Indicator Faults :

If other lamps flash dimly when indicators circuit is operating

This fault is usually caused by a high resistance to ground return due to bad connection (bad earth faulty ground) on the flasher lamp circuit due to corrosion or poor connection. May also be caused by several other factors such as:

  • Supply wiring under rated : too small cable used
  • Incorrect bulbs fitted
  • Short circuit on wiring loom, body control module, or switchgear.
  • Indicators flash rate too fast

    If the indicators flash too fast this may indicate that there is insufficient load on the direction indicator circuit.

    Possible cause:

  • Failure of one of the direction indicator bulbs
  • Incorrect wattage bulb fitted.
  • Faulty connection at lamp or body controller module
  • Most vehicles use a 21 watt bulb at each main indicator lamp (front & rear) and a 5 watt bulb at the side repeater lamp.

    Direction Indicator Circuit Blows Fuses

    If the indicator circuit causes a fuse to blow this usually means the insulation on wiring has become damaged causing a "short to ground".

    MoT Inspection  of Direction Indicators

    A check is carried out for :

  • Correct flash rate of lamps 60 to 120 flashes per minute
  • Direction indicator lamp operation "not adversely affected by the operation of another lamp".
  • Visibility  from front rear and side of the vehicle.
  • Lamps must emit an amber colour (first use date after 1st September 1965). Many manufacturers use a clear lens instead of the amber type. The indicator bulb where a clear lens is fitted is usually amber, the amber bulbs often lose their amber coating causing the indicator to then appear white. This is a reason for failure.
  • Completeness : Indicator Lenses must not be broken
  • Security - Lamps switches and wiring must be secure.
  • All indicators fitted must work
  • Operation of dash warning lamp or audible beep to notify driver indicator is operating but only required if indicator lamps can not be seen from drivers seat
  • Reference : Section 1.4 Mot inspection manual (2012)

    Multitimer (modern vehicles)

    Late model vehicles may use a "multi timer " unit built into the fuse board or body control module to operate direction indicators.
    The Multi timer often has several other functions related to timed circuits for example , interior light delay, alarm sounder , reverse bleeper, and windscreen wiper delay.

    Seperate relays may also be fitted for each flasher circuit

    Diagnostic testing of Indicator Circuit on vehicles with body controller module

    Diagnostic equipment with dedicated software can be used to check the direction indicator circuit on some vehicles where a body controller module is fitted.

    Diagnostic equipment live data readout of body module may show input signal from turn signal switch ON / OFF function and hazard warning lights switch active function .

    Diagnostic equipment Component actuation function can command body control module to operate indicator lamps allowing a quick functional check of lamp operation. Further testing of wiring continuity can be done with multimeter to check for breaks in wiring, short to ground.

    Classic Car Indicators

    Requirement for direction indicators depends on vehicle first use date.

  • 1st January 1936
  • Vehicles of first use date before 1st January 1936 currently have no legal requirement to be fitted with direction indicators

  • 1st September 1965
  • Vehicles of first use date prior to 1st September 1965 may combine indicators wit stop lamps or front/rear position lamps so front indicator may flash white, rear indicator may flash red.

  • 1st April 1986
  • Vehicles of first use date after 1st April 1986 must have side repeater lamps fitted but these can be incorporated within the front direction indicator lamp if a wrap around lens is fitted so lamp is visible from side.

    Semaphore Indicators

    Typical part number Lucas SF40 or Lucas SF80

    A semaphore arm raises outwards from the side of the vehicle body when direction indicator switch is activated. trafficator image

    Semaphore indicators (Trafficators) fitted to older classic and vintage vehicles often use an electromagnet to raise each semaphore arm.

    Semaphore indicators must also illuminate but do not have to flash. The semaphore indicators can also be wired to allow to flash.

    Many classic car owners have additional indicator lamps fitted for road safety and to protect their vehicle.

    Typical Direction Indicator Wiring Circuit Colour Codes on Classic British Vehicles

  • Green : Ignition circuits after ignition switch
  • Green/Pink : Ignition circuit via fuse supply to flasher relay
  • Green/Red : LH Turn Signal switch to Left hand direction indicator lamps
  • Green/White : RH Turn Signal switch to Right hand direction indicator lamps
  • 12N trailer wiring colour codes for Direction indicator circuit

  • Yellow (12N plug / socket terminal 1): Left hand Indicator
  • Green (12N plug / socket terminal 4) : Right hand indicator