Lotus Elan Central

OK, so you want to add something (in my case a heater for the three small dials to stop them misting up) and need a supply from the ignition. You want it to be professional and add a switch which is in keeping with the rest of the switches on the dash. You realise there are some blanks on the dash and manage to find a GM switch with a suitable logo, albeit with a white symbol. So where are you going to hack into the wiring loom and how are you going to get your switch wired up.

If you're lucky enough to have aircon and look down on us mere mortals during the Summer, luxuriating in your frosty interior............ tough! Check out the circuit diagrams and figure it out yourself.

If you're one of the masses who consider that dropping the hood and driving fast (within the legal limits of course) is sufficient air conditioning, then read on; I have a simple answer.

If you check out the circuit diagram for the AirCon on the Wiki (page 19) you'll see that the aircon switch, feeds the blower fan slow relay. The blank switch position is next to the hazard warning switch and is fully wired. The relay socket is under the binnacle at position N (see below) and is also fully wired.

All you need to do is get a suitable switch (e.g. Carlton front foglight GM 90 336 298) which will have pins 2,3,4,5,6 present and a couple of suitable spade terminals (4.8mm).

Pop the switch blank out, insert the switch, insert the spade connections into pins 1 and 2 of the relay socket and away you go.

okay, so you've suceeded in making a light switch -- bravo

Geoff, you forgot to tell us the max rating of the GM switch - just in case someone tries to use it to switch the Rad fans

Thanks Dave, it should be good for a couple of Amps - I think the fuse is 3A.

GeoffSmith wrote::oops: Thanks Dave, it should be good for a couple of Amps - I think the fuse is 3A.

Yep - 3A it is, Careful tho' as it also feeds the instruments. If you do use it then I recommend only for switching a relay.
Geoff, did you try plugging a relay in to see if the heater fan powers up? Looks like it would run on the slow setting?

DeeAitch wrote:did you try plugging a relay in to see if the heater fan powers up?

I presume you mean, "after taking the horn relay out of position O to determine which pin was which, after connecting the lamp to pins 1 and 2 in position N to make sure the relay drive wiring was correct, after shorting pins 3 to 5 in position N to make sure the fan came on at low speed, did I try the horn relay in the slow fan relay position before returning it to its correct position?"

Well, I cannot source 4.8mm male spades. Looks like they're going to have to be made from scratch.

The good news is that the switch now has a red logo.

GeoffSmith wrote:I presume you mean, "after taking the horn relay out of position O to determine which pin was which, after connecting the lamp to pins 1 and 2 in position N to make sure the relay drive wiring was correct, after shorting pins 3 to 5 in position N to make sure the fan came on at low speed, did I try the horn relay in the slow fan relay position before returning it to its correct position?"

Just about sums it up

No need, seeing as "shorting pins 3 to 5 in position N to make sure the fan came on at low speed" proves the point

I was just trying to figure a way of using the existing relay housing to power up something else

4.8mm spades? How many do you want

Red Logo Come on, spill the beans

Yes of course the fan worked with the horn relay in!

A few 4.8mm MALE spades (in slow time) would be good. I have now found some printed circuit board males but I would have to buy 100 @ 9p each!

Red logo was dead easy. I found some very thin red plastic (I used it decades ago for covering the hole in front of LED displays). I stuck double sided sticky tape on it, cut it out with a scalpel and stuck it on! I have very little left but I'll keep some for you if you want it.

I used to have loads of 'em - will dig deep in the junk pile tonight!

Been thinking tho' - why not pull the guts from a relay and solder in a flying lead? You then have a nice plug in job

Been thinking the same. Has anyone got a spare one? Don't think I can do without a horn.

GeoffSmith wrote:Don't think I can do without a horn.

Can't be having that - whatever would the Mackems think

Afraid I've not much in the way of male spades, - these are meant for rivets.
Take your pic - or fill ya boots

They'll do just fine, thank you kind sir.

Can you just use the purple wire from the digital clock to power a relay? It's quite close to the switch near the steering?


Cheers,

Phil

surferphil wrote:Can you just use the purple wire from the digital clock to power a relay? It's quite close to the switch near the steering?


Cheers,

Phil

Phil, I think that circuit is only up for 3 amps

DeeAitch wrote:Phil, I think that circuit is only up for 3 amps

Would that be enough to drive a relay? I want a boot realise switch and now I have tidied up the Alarm bits into 1 switch, I have a space. The air con switch is in the space Geoff is using for his, err... dial air con switch

So that's why I only have 1 space left, but with no receiver. But I do have air con

Got an even better fix for converting the switches from white to red - use a red indelible CD/DVD marker pen.

Do you need a horn relay Geoff?