Lucas Hazard Switch replacement for 1979 308

Based on the schematic symbols for the 4-terminal and 7-terminal 308 hazard switches ("pole" is really a special term used for a different thing wrt switches), you should be able to substitute the 7-terminal switch for the 4-terminal switch IMO (if you can figure out who's who on the 7-terminals switch ), but before going there, I believe that you can test your system to make sure there are no other problems by:

(Note -- these are the wire colors in the wiring harness of the car on the other side of the multi-pin connector -- not necessarily the wire colors between the multi-pin connector and the hazard switch itself)

1. With the two GN (yellow/black) wires connected together and the two H (grey) wires not connected together, this should be the same as the normal running condition and having the hazard switch "off" -- i.e., the blinkers should work normally (with the key "on") and the hazard lights should not be flashing.

2. With the two H (grey) wires connected together and the two GN (yellow/black) wires not connected together, this should be the same as having the hazard switch "on" -- i.e., (even with the key "off"), the hazard lights should flashing.

If you can pass these two tests, give a shout, and I think that with some resistance tests you could figure out who's who on the 7-terminal switch (and make the appropriate connections to replace the 4-terminal switch). However, if you can't pass these two tests, I'd conclude that you do have some other problem elsewhere that would need to be corrected first.

 

OK -- that says that the rest of your car is OK, and you only need to figure out how to use the 7-terminal switch in place of the 4-terminal switch. The figure below shows the schematic symbol for the 7-terminal switch.
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I've arbitrarily labeled the 7 terminals A thru G (there may be terminal numbers on the switch itself, but, since I don't have one, I've just given them random names). Using your Ohmmeter, see if you can identify A, B, and C. You won't be able to tell who's who for D, E, F, and G, but you should be able to deduce which 4 terminals are D, E, F, and G.

With the (unplugged) switch in the "off" position:
Terminal A should be connected to only terminal B
Terminal B should be connected to only terminal A
Terminal C should not be connected to any other terminal
Terminal D should not be connected to any other terminal
Terminal E should not be connected to any other terminal
Terminal F should not be connected to any other terminal
Terminal G should not be connected to any other terminal

With the (unplugged) switch in the "on" position:
Terminal A should be connected to only terminal C
Terminal B should not be connected to any other terminal
Terminal C should be connected to only terminal A
Terminals D, E, F, and G should all be connected together

To give the same operation as the 4-terminal switch, the two GN (yellow/black) wires in your harness should be connected to terminals A & B, and the two H (grey) wires in your harness should be connected to any two of the D,E,F,G terminals (although it would be best to use D & E or D & F if there are any markings on the switch that can indicate who's who).

Good luck, and give a shout if something else comes up -- otherwise, we'll expect to hear good news

 

Yes. Your car has a dedicated hazard relay which is why the hazard switch only needs 2 poles (4 terminals). Voltage is either sent to the hazard relay or the turn signal flasher relay, never both. But the large switch can be easily made to work.

The turn signal pole of the original switch gets voltage from the #1 fuse using a yellow/black wire. Coming from the switch also on a yellow/black wire going to the turns flasher (corner of the relay panel). This switch is normally on so turn signals normally work but is disabled with hazards on.

The gray wires from your switch get voltage from fuse #6 and turn them on/off to power the hazard relay gray wire. Incidently, the antenna switch also uses that fuse voltage.

Hint - Try 1-2 terminals for grays and 5-8 for yellows.

Or get diagrams from the donor car the switch is from in order to gain insight to adapting it to your car.

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Not kosher but I can see how 7-8 can be made to work. For the future I still hold out for 5-8 but wouldn't take it apart when you're pleased to having it working again.

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