MGA 1500 (Early) Hazard Warning Switch Installation

As we all know, our British automobiles have a reputation for occasional tempermental behavior which sometimes results in the car's unwillingness to propel itself down the road. In other words, it stops running! This can occur any time, and with the density of traffic on the roads today, safety is very important.

A hzard warning switch is a good safety accessory which should be considered for any British car owner who drives his or her car regularly. A Lucas hazard warning switch (4-way flasher) is available from Victoria British. The installation of a hazard warning switch into an early MGA 1500 does not conform to the directions provided with the unit when used on early MGAs with a direction indicator relay unit. The intallation is a bit more involved, but can be performed by an owner with a little understanding of electrical circuits.

These items are required..

The Lucas hazard warning switch is a self contained switch/flasher unit mounted on a bracket with an in-line fuse and cover. The switch and flasher can be removed from the bracket if you want to mount the switch into the dash. For this application, we will use the unit as-is on the bracket and mount the assembly under the dash on existing dash support brackets. As purchased, the hazard warning switch is pre-wired but has two empty terminals. In this early MGA applicatoin, you must add a wire to each of these empty terminals. If you have access to an old wire harness, you can get the colored wires listed above. If not, get two 16 AWG wires and attach on to each of the terminals. It does not matter which wire goes to which terminal.

For the wires listed, install lugs as follows:

Wire... Connect to...
Black wire Ring terminal
Green / red Spade lug
Green / white Spade lug
White / purple Spade lug
White / brown Spade lug
Green / brown Push-on or ring terminal

Check your flasher: if it's original, it will have screw terminals, so use the ring terminal on the wire. If it's a later version, it will have push-on terminals.

The other green / brown and purple wires do not get terminals


The flasher unit can be mounted under and behind the dash on the brackets that support the dash and mount the speaker enclosure. If your car has no speaker enclosure, the instructions are the same, but you will have to supply the screws and nuts called for which hold the speaker enclosure. If the brackets pictured below are missing, you can obtain them from Clarke Spares and Restorations (90 West Swamp Rd., Doylestown, PA 18901, 215-348-0595) and refer to "stiffener" part number M18 LH and RH.


A mounting bracket is needed in order to fit the 4-way flasher on the dash support brackets. To make a sturdy mounting with no holes to drill in the car, make a mounting bracket from 1/16 inch steel or aluminum as follows.

End holes: clearance for the existing bracket screws
Center hole: drill for the self-tapping screw provided with flasher


Mount the right side of the flasher to the center hole of the bracket. Don't forget to put the cover on. Remove the two screws holding the speaker enclosure. Offer up the flasher/bracket and mount the left side screw through the flasher/bracket. Mount the right side bracket to the support and also connect the black wire under the screw before tightening. The flasher should now be in place under the dash.



Disconnect the battery.

Locate the grommet where the main harness passes through the firewall. Feed the remaining wires through the hole into the engine compartment. The wires should be long enough to reach the flasher, direction indicator relay, and the fuse box. Wire connections are as listed in the table and are explained below.

Wire... Terminal Installed Connect to...
Green / brown None Fuse box A4
Green / brown Ring or push-on Flasher terminal B
Purple None Fuse box A1
Black Ring Screw on bracket
Green / white Spade Dir. indicator relay terminal 2
White / brown Spade Dir. indicator relay terminal 3
Green / red Spade Dir. indicator relay terminal 6
White / purple Spade Dir. indicator relay terminal 7



  1. Locate the wire from the fuse box to the existing flasher unit. If you have an ohmmeter, remove the green wires on the A4 terminal of the fuse box and disconnect the green wire from the flasher terminal B. Find the wire by checking for continuity.
  2. If you do not have a multimeter, you can find the wire by removing one green wire at a time from the fuse box (leave all the wires connected to the flasher) and then trying the turn signals. When the signals don't work, that is the wire. You will not use this wire, so you can lay it back into the harness out of the way.
  3. Connect the rest of the green wires back to the fuse box terminal A4 along with the (stripped) green / brown wire from the 4-way flasher.
  4. Connect the purple wire from the 4-way flasher to the A1 terminal of the fuse box.
  5. Connect the green / brown wire with the lug on it to the flasher terminal B.
  6. Run the rest of the wires over to the direction indicator relay. The terminal numbers are stamped into the cover of the relay unit.
  7. Connect the green / white wire to terminal 2.
  8. Connect the white / brown wire to terminal 3.
  9. Connect the green / red wire to terminal 6.
  10. Connect the white / purple wire to terminal 7.
  11. Tuck in the wires, pull excess wire back under the dash, use tie wraps to hold them in place, and the installation is complete.



Reconnect the battery. Check the 4-way flasher by pulling out the switch. The turn signal lamps should all flash, along with the indicator in the switch. The hazard signals should flash with the ignition key off or on. With the key on and the 4-way off, check that the turn signals still work normally. Pull out the 4-way switch: all lamps will flash and the turn signals will stop.

Congratulations! You now have a hazard warning flasher for those rare occasions where you may have to stop on the side of the road. We know you won't need to use it (much), but you can feel a little more secure knowing the 4-way flasher is available if ever you should need it.

Safety Fast!