Lotus Elan

Anti Theft Switch Location?

PostPost by: hubrick » Fri Mar 20, 2020 4:22 pm

Hi All,
I'm a brand new first time Lotus owner, having just in February bought a 70 Elan from California (I'm in Louisiana). I sure am delighted to have found an owner's group to communicate with. On about my 10th drive the tach went to 0 and the engine died simultaneously, actually 2 or 3 times before it became permanent. Troubleshooting, I don't have any power to the white wire at the coil with the key turned on. I've put a jumper wire from the white wire at the fuse to the coil, and it starts and runs fine. The wiring diagram shows an Anti Theft Switch is the only thing the white wire goes to/through before the coil. I guess it could be a connect in the ignition switch too. Anything else? Can anyone tell me where I can find the Anti Theft Switch, and if the consensus is that bypassing that switch will solve my problem? I also see the Purple with Black tracer goes from that switch to the horn, so am I going to have trouble with the horn if I bypass that switch. Perhaps someone can explain the functionalilty of the switch.
Thanks,
Rick
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PostPost by: LaikaTheDog » Fri Mar 20, 2020 7:25 pm

Never seen one, but saw somewhere on this forum that they were in or close to the glovebox.
Last edited by LaikaTheDog on Sat Mar 21, 2020 5:21 pm, edited 1 time in total.
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PostPost by: mbell » Fri Mar 20, 2020 8:02 pm

The switch should be mounted to the glove box and switched from inside the glove box.

Circuit should roughly be battery -> ign switch -> Theft switch -> coil. With the switch "activated" it should sound the horn rather than power the coil.
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PostPost by: oldelanman » Fri Mar 20, 2020 8:06 pm

Hi Rick, Welcome to the forum.
The so-called anti-theft switch is a small double pole slide switch located in the glove box. The feed from the ignition switch to the coil passes through one side and the other side takes a feed from the horn circuit to earth. In normal operation the ignition circuit is connected and the horn is isolated, in anti-theft mode the ignition circuit is disconnected and the horn is earthed so if the ignition switch is turned on the car will not start but the horn will sound. Your switch may be partially operated so the ignition doesn't work but the horn does not sound. If you slide the switch back and forth a few times it may work but it is unreliable and most people bypass it.

It's a bit tricky to get to as it's mounted on the outside of the glove box but here's what you need to do to bypass it....

Anti-theft switch.JPG and
Join white wires and insulated the other two


The normal operation of the horn will not be affected.

Hope this helps.
Roger
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PostPost by: hubrick » Fri Mar 20, 2020 11:33 pm

Wow, you guys are great help! Took out the glove box, went right to the switch! Unfortunately, none of the connections were loose, the switch seemed to work crisply back and forth, but the bad part is that neither one of the white wires had any power with the ignition switch turned on. So that means I go back to the switch or to the tachometer. I'm thinking the wire is continuous and not connected to the tachometer, but there are two bullet connectors before and after the tachometer, which may be the culprit. The back of the speedo looks relatively accessible, but not the tachometer. Any guidance on getting to the back of it?
Thanks again, marvelous support and help.
Cheers,
Rick
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PostPost by: oldelanman » Sat Mar 21, 2020 10:27 am

Hi Rick,
Assuming you have the later type tacho, the two bullet connectors shown in the wiring diagram are actually connected directly to the back of the tacho and may just be visible with the aid of a mirror or by taking a pic with your mobile phone up behind the dash, you might be able to see if one has become dislodged. The connectors are one male and one female so not possible to fit to the wrong terminal and they can be connected together to bypass the tacho if you think the break in the circuit may be internal.
Rear of tacho.jpg and
Tacho connections

The back of the dash is awkward to get to and in the past I have removed the driver's seat and laid on my back with my head in the footwell to work on it. Removing the radio or the ashtray gives access to some of the wiring and maybe you can access the back of the tacho by removing the speedo, if that's easier to get to, and working through the hole ?
Be aware also that the voltage stabiliser is mounted on the back of the speedo not on the tacho as shown on the wiring diagram .. that may confuse you when trying to find your way around by feel or with a mirror !
Roger
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PostPost by: hubrick » Sat Mar 21, 2020 1:10 pm

Hi Roger,
Thanks for the picture and the great description. Sounds like a mighty challenge. Hopefully I'll be able to get to it today and try to find it.
Cheers,
Rick
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PostPost by: pharriso » Sat Mar 21, 2020 2:04 pm

Why are we posting in public about the anti-theft switch & it's location? It will be Googleable by any car thief. :roll:

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PostPost by: oldelanman » Sat Mar 21, 2020 4:03 pm

pharriso wrote:Why are we posting in public about the anti-theft switch & it's location? It will be Googleable by any car thief. :roll:

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You have a PM.
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PostPost by: Craven » Sat Mar 21, 2020 4:26 pm

Why would a thief have the ignition key.
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PostPost by: 69S4 » Sat Mar 21, 2020 4:45 pm

My switch went long ago. I suspect it's probably stopped more owners driving the car than thieves.
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PostPost by: Grizzly » Sat Mar 21, 2020 6:57 pm

pharriso wrote:Why are we posting in public about the anti-theft switch & it's location? It will be Googleable by any car thief. :roll:

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Just trying to figure out if this is tongue in cheek (have you tried googling it already? this isn't the first thread about it) ........ if anyone wanted to steal an Elan all it would take is 12" of wire and some thing to ark out the start solenoid unless you have some thing a dam sight better than the original theft switch and key :lol:

In my personal opinion your better loosing the original switch (they are more of a hindrance than a help anyway) and do some thing a little more original to stop your car being taken.
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PostPost by: hubrick » Mon Mar 23, 2020 1:46 pm

Hello Roger/All,
Got the Lotus out yesterday, and leaned under the steering wheel to try to look at the back of the tach. Tried my phone camera too. Can't see clearly the connection for the white wire in and out. Can reach the knurled nut on the speedo side, but not on the other side. Thinking the only way to get at it is to pull the dash out. I see a bunch of large screw heads in the dash. What would I have to do to get the dash loose and be able to pull it backwards far enough to see the wiring on the back of the tach?
Or conversely, does it sound like my problem could be at the ignition switch it self? I didn't think so because with the switch on the fuel pump runs, actually the car starts when I run a jumper wire from the fuse block to the coil.
Cheers,
Rick
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PostPost by: Craven » Mon Mar 23, 2020 2:20 pm

Here are a couple of pic’s off the internet. They show the insides of the RV, as you can see the white wire is continuous just terminating in the bullet connectors. So if at fault can only really be the push on connections. Possible as they do carry the coil current.
You must have a +2 as on an Elan removing the under side dash trim gives access.
tacho3.jpg and

tacho1.jpg and
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PostPost by: hubrick » Mon Mar 23, 2020 2:36 pm

One more thing. The back of my tach looks much more complicated than the picture Roger posted. The wiring diagram for my Series 4 shows the high beam warning light, the ignition warning light, so when I looked and tried to take pictures yesterday, I saw that jumble of wires and couldn't see through them well enough to see the white wire connections. I'll try it again with the seat out.
Cheers,
Rick
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