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Hazard warning light toggle switch


MikeE

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drove the SL to work this morning and noticed the indicators weren't working. I assume it was probably just a fuse so I continued to work. Onced I'd arrived I thought I'd see what else wasn't working so tried the hazards. As soon as I toggled the switch I heard an electrical buzzing (shorting sound) so tried to turn it off. However the switch didn't seem to want to and next thing I know there's smoke coming out. So I get behind the dash and rip the wires out the back *eek*

 

Does anyone know where I can source a new switch without having to resort to the Caterham spares department (again) 🤔

 

Once I've fixed the switch which fuse(s) do I need to check (and whee are they).

 

thanks,

Mike

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Mike

 

The fuses are under the passenger side dash near where the passenger's knee would be. They are usually hidden behind a largish "coal-hod" shaped plastic cover which just pulls off (attached by velcro). Fuse 12 (10 amps) is the indicator fuse.

 

The buzzing you heard is not an electrical short but a peculiarity of the switch that Caterham have used historically. It contains a buzzer for some strange reason that even Caterham have forgotten.

 

I'll look up a source of switches and send you the circuit for rewiring it.

 

Chris

 

1.8K SV 140hp see it here

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Actually the hazard switch from Caterham is relatively good value - shown as £5.46 on their parts CD whereas Vehicle Wiring Products charge £18.19 + VAT. Both of these will have P&P on top as well.

 

I would recommend getting a replacement from Caterham as they have their own way of wiring the hazard and indicator circuits together. I fully understand how it all works but with a different switch there may be some rewiring to do so I would advocate the easy method.

 

One caution - we don't yet know what the fault is. Changing the switch may not solve the problem. If you have access to an ohm meter the hazard switch should do the following:

 

There are 6 contacts on the back of it - a group of 4 close together and a group of 2 close together plus a small connector on either side of the casing. Do these tests with the switch out of the car, ie: disconnected.

 

1. With the switch OFF, the group of 2 should be connected together. The group of 4 should be connected to nothing, not to themselves nor to the group of 2.

 

2. With the switch ON, the group of 2 should be disconnected from each other (and anything else). The group of 4 should be all connected to each other.

 

3. In both cases (ON or OFF) there should be around 60 ohms resistance between the two small side connectors.

 

If this checks out, the switch is probably OK and the fault lies somewhere else. The curious thing is the smoke, as the whole hazard/indicator circuit is protected by a 10A fuse. Can you check that no-one in the past has put a much higher value in (like a Polo packet!). If you had a short, the fuse would blow immediately with no time for smoke.

 

By the way, the Caterham wiring diagram and the handbook show a "hazard relay" as if this is controlling the hazard lights. It's not. It's an "indicator relay" - pull it out and the indicators will stop working but the hazard lights will continue to work.

 

It's used solely to make the indicators reliant on the ignition being ON. The relay is switched ON all the time the ignition is ON, and the indicators derive their +12v through the relay contacts and the flasher unit. The hazard switch bypasses this relay and puts +12v direct from the battery on to the indicator lamps through the flasher unit. Both circuits use the same 10 amp fuse (No. 12) as protection.

 

Chris

 

1.8K SV 140hp see it here

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OK I've now taken the switch to bits and examined it and all seemed OK so I put it back in the car and got the following symptoms:

 

1. I connected the 6 terminal block connector,

 

2. Put the switch in the OFF position and tried both left and right indicators which now work,

 

3. Put the switch in the ON position and but nothing seems to happen, no hazard lights and no buzzing (apart from the turn signal doesn't now work but this is to be expected?).

 

4. I connect the two additional spade connectors with the switch in the OFF position, the indicators still work,

 

5. I put the switch in the ON position and I get a load buzzing sound from under the dash (on the bulkhead somewhere?) but the hazards don't work!

 

Any ideas what's going on here? It's clearly not the switch (although I do believe when this originally went wrong the sliding terminals inside the switch had come adrift, hence the indicators not working, but I've rebuilt this now).

 

One strange thing is that when I origanlly pulled the terminals off the back of the switch (in a panic!) I shorted one of the external spade connectors against the dash frame and got a spark. I inadvertently did the same last night and got another spark. I would have thought this circuit should have been protected by a fuse but it doesn't seem to be.

 

BTW I checked the 'Indicator fuse' and it is a 10amp fuse so that looks OK.

 

Any advice greatfully recieved.

 

cheers,

Mike.

 

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Mike

 

These instructions will check definitively whether the hazard switch is faulty or not.

 

Disconnect the hazard switch and, as per my previous post above which described the connections on the back, suggest you do the following.....

 

All these instructions refer to the hazard connecting block, NOT the hazard switch unless otherwise specified.

 

1. Join the group of two connectors on the block together with a short link of wire pushed into the female connectors on the front of the block.

 

2. Put a second link from either one of these 2 connectors to the connector which has a light green/pink wire connected to it at the back. I haven't looked this morning but I recall it's one of the nearest connectors in the group of 4.

 

3. With the ignition ON, the indicators should now function OK when you use the indicator switch. Have you got enough hands left!!!

 

4. Switch OFF the ignition and remove all the wire links you just temporarily inserted.

 

5. Using wire links again, temporarily connect together the whole group of 4 female connectors leaving the earlier group of 2 disconnected. You will find that the hazard lights all come on. You shouldn't need to switch on the ignition for this. Then disconnect all the temporary wire links.

 

6. If this all works, it means the wiring is perfect and any fault is in the switch.

 

 

The side connectors illuminate the switch and operate that infuriating buzzer. One is a black earth wire and the other is a tap off the light green/pink wire which brings power to the hazard lamp from the flasher unit.

 

Unlike the other instrument illumination, the illumination is not derived from the fuse box but from the supply to the hazard switch. That's why it sparked, because the only protection is to the flasher itself via fuse 12. The flasher unit is an electronic unit and not a mechanical unit so temporarily brushing the light green/pink wire against the dash was like connecting a bulb very quickly. I imagine that's why you had smoke the other day because you shorted the light green/pink wire to the dash and the wire itself was acting as a fuse, got very hot and the insulation started to smoke.

 

If all the above works, but it doesn't when you reconnect the switch, I would replace the hazard switch as it clearly has a problem.

 

Come back if all is not clear

 

rgds

 

Chris

 

1.8K SV 140hp see it here

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From other postings in the past it was recommended to turn switch on frequently as they need to be used to keep the contacts clean. If not used it will stop the indicators working.

 

Richard in France

with a yellow rolling chassis, Duratec engine and most parts to complete 😬 *thumbup* 😬 😬

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