Auto electricians - help! Wiring up a UK Subaru rear foglight switch on my import
13 August 2005, 03:59 PM
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Auto electricians - help! Wiring up a UK Subaru rear foglight switch on my import
This problem has been doing my head in, and I just can't think clearly about what needs doing. Help!
When I bought my MY98 WRX, it had a rear 'foglight' (i.e. the reversing light put into the red part of the cluster) that had been wired to work off of the front foglight switch. Fair enough, but I thought it would be a lot tidier to have its own separate switch. I managed to get hold of a proper rear foglight switch from a scrapped UK turbo plus the wiring plug, which for some reason has only 5 wires instead of 6.
Anyway, I removed the lower dash and can see what's what. There is a wire that runs to the rear which basically basically just wants 12v put down it to light the 'foglamp'. So far so good. This was fed from a 5 pin relay with what appeared to be only two inputs. I don't know how that can be, but maybe I pulled a wire off and didn't realise it? The two wires to feed the relay came from the wiring loom going to the front foglight switch - one which seems to be an earth had simply been cut between the switch and the dash, and rerouted from the switch to the relay. The other wire had been teed off from what seems to be the illumination feed - i.e. the 12v that comes on when either headlights or foglights are on.
Having disconnected the relay to the rear and reconnected the cut earth wire - putting it back to 'factory' - testing shows that the new 'rear' switch works just as well as the 'front' switch in every way...it illuminates when you put the lights on, it switches the front fogs on and off, the orange telltale light comes on when the front fogs are on. So I assumed that the internal layout must be the same for both switches although the rear one lacks one of the pins.
Next I made a kind of 6-way Y-connection between the two switches, but of course all that I achieved was to end up with two separate switches that can both switch the front fogs on and off independently of each other! So I guess what I need to do is take just the minimum required to illuminate correctly, give a 12v output when switched and light the telltale lamp when ON. This is where I'm struggling! Everything wiring scheme I think of is just getting back to a simple Y-connection with the existing front switch!
This is what I know about the front switch, pins 1 to 6, ignition is on and the switch is actually wired into the circuit:
1 Permanent 12v
2 12v when switch is OFF / 0v when switched ON
3 12v when headlights or foglights are ON (Illumination circuit live?)
4 Permanent 0v
5 +12v when lights or switch are OFF (i.e. opposite of pin 3)
6 Permanent 0v
Pin 3 was originally teed off to feed the relay, pin 5 was originally rerouted to the relay rather than back into the dashboard loom.
What I know about the new rear foglight switch is this:
pins 1,2 and 4 are connected together internally. Voltage across pins 1 and 4 will light the telltale. Voltage across pins 3 and 6 will illuminate the switch for night time driving. pin 2 I'm not sure about, I thought it gave a 12v output when switched on, but I might have muddled that. pin 5 is not connected at all - it's plastic not metal.
Help!!!
One other thing - there is also an unused brown plug (doesn't quite fit my switch) that goes 12v on pin 3 as well when you switch the lights on. Everything else reads zero with ignition or lights on or off. Obviously it's for an optional extra switch with illumination - could it be for intercooler water spray?
When I bought my MY98 WRX, it had a rear 'foglight' (i.e. the reversing light put into the red part of the cluster) that had been wired to work off of the front foglight switch. Fair enough, but I thought it would be a lot tidier to have its own separate switch. I managed to get hold of a proper rear foglight switch from a scrapped UK turbo plus the wiring plug, which for some reason has only 5 wires instead of 6.
Anyway, I removed the lower dash and can see what's what. There is a wire that runs to the rear which basically basically just wants 12v put down it to light the 'foglamp'. So far so good. This was fed from a 5 pin relay with what appeared to be only two inputs. I don't know how that can be, but maybe I pulled a wire off and didn't realise it? The two wires to feed the relay came from the wiring loom going to the front foglight switch - one which seems to be an earth had simply been cut between the switch and the dash, and rerouted from the switch to the relay. The other wire had been teed off from what seems to be the illumination feed - i.e. the 12v that comes on when either headlights or foglights are on.
Having disconnected the relay to the rear and reconnected the cut earth wire - putting it back to 'factory' - testing shows that the new 'rear' switch works just as well as the 'front' switch in every way...it illuminates when you put the lights on, it switches the front fogs on and off, the orange telltale light comes on when the front fogs are on. So I assumed that the internal layout must be the same for both switches although the rear one lacks one of the pins.
Next I made a kind of 6-way Y-connection between the two switches, but of course all that I achieved was to end up with two separate switches that can both switch the front fogs on and off independently of each other! So I guess what I need to do is take just the minimum required to illuminate correctly, give a 12v output when switched and light the telltale lamp when ON. This is where I'm struggling! Everything wiring scheme I think of is just getting back to a simple Y-connection with the existing front switch!
This is what I know about the front switch, pins 1 to 6, ignition is on and the switch is actually wired into the circuit:
1 Permanent 12v
2 12v when switch is OFF / 0v when switched ON
3 12v when headlights or foglights are ON (Illumination circuit live?)
4 Permanent 0v
5 +12v when lights or switch are OFF (i.e. opposite of pin 3)
6 Permanent 0v
Pin 3 was originally teed off to feed the relay, pin 5 was originally rerouted to the relay rather than back into the dashboard loom.
What I know about the new rear foglight switch is this:
pins 1,2 and 4 are connected together internally. Voltage across pins 1 and 4 will light the telltale. Voltage across pins 3 and 6 will illuminate the switch for night time driving. pin 2 I'm not sure about, I thought it gave a 12v output when switched on, but I might have muddled that. pin 5 is not connected at all - it's plastic not metal.
Help!!!
One other thing - there is also an unused brown plug (doesn't quite fit my switch) that goes 12v on pin 3 as well when you switch the lights on. Everything else reads zero with ignition or lights on or off. Obviously it's for an optional extra switch with illumination - could it be for intercooler water spray?
Last edited by Nick Read; 13 August 2005 at 04:01 PM.
13 August 2005, 04:47 PM
#2
Would'nt it be easier to wire the fog light through a relay using your new switch ?Thats how the oem circuit is..
Sounds like someone wired it up in a fashion through the relay without going through the coil LOL
I f you need i can tell you how ?
Sounds like someone wired it up in a fashion through the relay without going through the coil LOL
I f you need i can tell you how ?
Originally Posted by Nick Read
This problem has been doing my head in, and I just can't think clearly about what needs doing. Help!
When I bought my MY98 WRX, it had a rear 'foglight' (i.e. the reversing light put into the red part of the cluster) that had been wired to work off of the front foglight switch. Fair enough, but I thought it would be a lot tidier to have its own separate switch. I managed to get hold of a proper rear foglight switch from a scrapped UK turbo plus the wiring plug, which for some reason has only 5 wires instead of 6.
Anyway, I removed the lower dash and can see what's what. There is a wire that runs to the rear which basically basically just wants 12v put down it to light the 'foglamp'. So far so good. This was fed from a 5 pin relay with what appeared to be only two inputs. I don't know how that can be, but maybe I pulled a wire off and didn't realise it? The two wires to feed the relay came from the wiring loom going to the front foglight switch - one which seems to be an earth had simply been cut between the switch and the dash, and rerouted from the switch to the relay. The other wire had been teed off from what seems to be the illumination feed - i.e. the 12v that comes on when either headlights or foglights are on.
Having disconnected the relay to the rear and reconnected the cut earth wire - putting it back to 'factory' - testing shows that the new 'rear' switch works just as well as the 'front' switch in every way...it illuminates when you put the lights on, it switches the front fogs on and off, the orange telltale light comes on when the front fogs are on. So I assumed that the internal layout must be the same for both switches although the rear one lacks one of the pins.
Next I made a kind of 6-way Y-connection between the two switches, but of course all that I achieved was to end up with two separate switches that can both switch the front fogs on and off independently of each other! So I guess what I need to do is take just the minimum required to illuminate correctly, give a 12v output when switched and light the telltale lamp when ON. This is where I'm struggling! Everything wiring scheme I think of is just getting back to a simple Y-connection with the existing front switch!
This is what I know about the front switch, pins 1 to 6, ignition is on and the switch is actually wired into the circuit:
1 Permanent 12v
2 12v when switch is OFF / 0v when switched ON
3 12v when headlights or foglights are ON (Illumination circuit live?)
4 Permanent 0v
5 +12v when lights or switch are OFF (i.e. opposite of pin 3)
6 Permanent 0v
Pin 3 was originally teed off to feed the relay, pin 5 was originally rerouted to the relay rather than back into the dashboard loom.
What I know about the new rear foglight switch is this:
pins 1,2 and 4 are connected together internally. Voltage across pins 1 and 4 will light the telltale. Voltage across pins 3 and 6 will illuminate the switch for night time driving. pin 2 I'm not sure about, I thought it gave a 12v output when switched on, but I might have muddled that. pin 5 is not connected at all - it's plastic not metal.
Help!!!
One other thing - there is also an unused brown plug (doesn't quite fit my switch) that goes 12v on pin 3 as well when you switch the lights on. Everything else reads zero with ignition or lights on or off. Obviously it's for an optional extra switch with illumination - could it be for intercooler water spray?
When I bought my MY98 WRX, it had a rear 'foglight' (i.e. the reversing light put into the red part of the cluster) that had been wired to work off of the front foglight switch. Fair enough, but I thought it would be a lot tidier to have its own separate switch. I managed to get hold of a proper rear foglight switch from a scrapped UK turbo plus the wiring plug, which for some reason has only 5 wires instead of 6.
Anyway, I removed the lower dash and can see what's what. There is a wire that runs to the rear which basically basically just wants 12v put down it to light the 'foglamp'. So far so good. This was fed from a 5 pin relay with what appeared to be only two inputs. I don't know how that can be, but maybe I pulled a wire off and didn't realise it? The two wires to feed the relay came from the wiring loom going to the front foglight switch - one which seems to be an earth had simply been cut between the switch and the dash, and rerouted from the switch to the relay. The other wire had been teed off from what seems to be the illumination feed - i.e. the 12v that comes on when either headlights or foglights are on.
Having disconnected the relay to the rear and reconnected the cut earth wire - putting it back to 'factory' - testing shows that the new 'rear' switch works just as well as the 'front' switch in every way...it illuminates when you put the lights on, it switches the front fogs on and off, the orange telltale light comes on when the front fogs are on. So I assumed that the internal layout must be the same for both switches although the rear one lacks one of the pins.
Next I made a kind of 6-way Y-connection between the two switches, but of course all that I achieved was to end up with two separate switches that can both switch the front fogs on and off independently of each other! So I guess what I need to do is take just the minimum required to illuminate correctly, give a 12v output when switched and light the telltale lamp when ON. This is where I'm struggling! Everything wiring scheme I think of is just getting back to a simple Y-connection with the existing front switch!
This is what I know about the front switch, pins 1 to 6, ignition is on and the switch is actually wired into the circuit:
1 Permanent 12v
2 12v when switch is OFF / 0v when switched ON
3 12v when headlights or foglights are ON (Illumination circuit live?)
4 Permanent 0v
5 +12v when lights or switch are OFF (i.e. opposite of pin 3)
6 Permanent 0v
Pin 3 was originally teed off to feed the relay, pin 5 was originally rerouted to the relay rather than back into the dashboard loom.
What I know about the new rear foglight switch is this:
pins 1,2 and 4 are connected together internally. Voltage across pins 1 and 4 will light the telltale. Voltage across pins 3 and 6 will illuminate the switch for night time driving. pin 2 I'm not sure about, I thought it gave a 12v output when switched on, but I might have muddled that. pin 5 is not connected at all - it's plastic not metal.
Help!!!
One other thing - there is also an unused brown plug (doesn't quite fit my switch) that goes 12v on pin 3 as well when you switch the lights on. Everything else reads zero with ignition or lights on or off. Obviously it's for an optional extra switch with illumination - could it be for intercooler water spray?
13 August 2005, 06:47 PM
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Originally Posted by morpheous
Would'nt it be easier to wire the fog light through a relay using your new switch ?Thats how the oem circuit is..
Sounds like someone wired it up in a fashion through the relay without going through the coil LOL
I f you need i can tell you how ?
Sounds like someone wired it up in a fashion through the relay without going through the coil LOL
I f you need i can tell you how ?
Alternatively, just tell me what to wire to what and that will be a huge help! I'm not that great on relays.
14 August 2005, 12:39 AM
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Originally Posted by Nick Read
tell me what to wire to what and that will be a huge help! I'm not that great on relays.
Switch contact info + How I wired up mine :-
14 August 2005, 10:16 AM
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Originally Posted by Ken Ross
Hope these help
Switch contact info + How I wired up mine :-
Switch contact info + How I wired up mine :-
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