wiring up a modern key switch

Doc Sprocket wrote:

As I understand it, the whole point of using 87A is that it (earths) grounds when the trigger coil is de-energized with the switch in the OFF position- thus completing the path from the engine's kill wire (terminal 30) to ground (earth). Remember that the engine's kill circuit must be "closed" (completed, continous to earth) to shut down. Hence the need for the relay in the 1st place to use the "incompatible" key switch.

All Earths may be interconnected.

Please note that in order for the system to work, 12v must be maintained at the relay or the engine will not run. Ensure the relay is powered up before attempting to start. If, for example- you were to try and jump start engine by applying 12v+ directly to the starter terminal, engine will crank over but not fire unless you feed the relay coil 12v at the same time.

I see a switch with a light in your future LOL, Also so you don't kill the batt when giving the relay 12v all the time.

It won't kill the battery as long as the charging system is working. 12v is delivered to the relay trigger coil in the key's ON position.

Doc Sprocket wrote:

As I understand it, the whole point of using 87A is that it (earths) grounds when the trigger coil is de-energized with the switch in the OFF position- thus completing the path from the engine's kill wire (terminal 30) to ground (earth). Remember that the engine's kill circuit must be "closed" (completed, continous to earth) to shut down. Hence the need for the relay in the 1st place to use the "incompatible" key switch.

All Earths may be interconnected.

Please note that in order for the system to work, 12v must be maintained at the relay or the engine will not run. Ensure the relay is powered up before attempting to start. If, for example- you were to try and jump start engine by applying 12v+ directly to the starter terminal, engine will crank over but not fire unless you feed the relay coil 12v at the same time.

Ok Here we go made up switch unit just need to plug it in and try it will let you know if it starts before cutting in 19mm hole into dash

Doc is correct. The point of using 87A is so that the connection only happens when the power to the relay is off.


The relay works like this:

When coil is not energized
30 (which in the schematic is connected to ground) will be connected to 87A
87 will be open
This causes the coil to ground out and the engine to shut down

When coil is energized
30 (which in the schematic is connected to ground) will be connected to 87
87A will be open
This stops the coil from being grounded and allows the engine to run

TheRainbowBoxer wrote:

When coil is energized
30 (which in the schematic is connected to ground) will be connected to 87
87A will be open
This stops the coil from being grounded and allows the engine to run

I think you mean 87 here not 87A.

I have connected with the following wiring
B red red two wires BAT on new switch
S red yellow stripe STR on new switch
M red silver stripe. RELAY 86
G Black to RELAY 87A, 85
A red black stripe ACC on new switch
RELAY 30 Common to coil on engine

I am not sure A red black stripe should go on ACC on new switch this is the park position for the switch G think it should go on IGN?

No- Stick to what TRB said. You NEED it that way. engine kill circuit must NOT be completed to earth in order for the engine to run. When circuit is complete to earth, engine will NOT run.

Doc Sprocket wrote:

No- Stick to what TRB said. You NEED it that way. engine kill circuit must NOT be completed to earth in order for the engine to run. When circuit is complete to earth, engine will NOT run.

87 is not connected 87A is connected to earth as was taken from diagram above?

Correct. Instead of getting lost in potentially confusing verbal descriptions, simply wire the relay according to the schematic TRB drew up. While the actual "Drawing" of the relay could be a bit misleading, the termination numbers ARE correct. Ignore terminal 87, it's not being used here. 85 and 86 are the trigger coil in the relay, 30 and 87A are what complete the engine's KILL circuit to turn the engine OFF.

My Ignition switch didnt work . I took all the wires of the switch iyt still ran I connected all of the wires together it still ran has someone bypassed the switch

R/Y is connected in black with the switch turned off

Gazelle actual Wiring Diagram the other one was wrong page 1 sorry google found it


From this the wiring colors would be different as would the switch poles:
L Two red wires
M Ignition switch light Red yellow stripe
B Battery Red  with black stripe
S Starter Red with Silver stripe
GND Black

The diagram just says Engine Cut off for this but the switch in the off position seems to be connected to M ignition switch.

Switch connections
ign pos 1    ->           B connects to L, Gnd Not connected to M goes to outside of switch.
ign starter  ->>       S connects to Battery, B connects to L, Gnd Not connected to M goes to outside of switch.

I think therefore
87 should be M
87a should be earth on tractor
30 should be G
85 should be ground tractor

On new switch
BAT should be B
IGN should be 86 and L
ST should be S


Can anyone help please?

Well it got dark lol,

Had one amber light no start but could not see to do much. Had pulled red ignition contacts off so need to check those tomorrow are on properly. Also could not see if I had petrol Starter clicked but no spin of starter was detected but that could be an earth issue as all tin ware was painted.

All working if beit the starter making a racket:


Just need to work out how to put on rear lights and put on number plates any suggestions please