Ignition key question

[stugilmour]

Doing up my wiring loom. Dash and wiring are out of the car and spread out all over the family room floor. Want to finish up this weekend to give the room back to my long suffering wife.

Checked the key ignition switch with an ohm meter. Appears the coil supply wire terminal (connected to the "run" terminal) is not hot when key is in the "start" position. Think this would mean the car will only fire when the spring turns the key back to the "run" position, the starter kicks out, and the engine keeps turning from momentum. Seem to recall this was how it worked when I had the car on the road; luckily it fired right up so not completely sure.

Is this normal for the Lotus? Is my ignition switch pooche? Or am I missing something in how to wire it? Is a replacement key a pretty easy item from Moss North America; if so what car would have the same one? I have a local Moss supplier so way easier for me to order from them by specific part number (they don't list Lotus, but have Triumph, MG, etc.).

thx in advance

[Frank Howard]

Stu,

When you turn the key to the "start" position, you're sending 12V to the starter solenoid. The solenoid in turn sends 12V to the coil. It also sends 12V and plenty of amps (through the thick wire) to the starter motor. When the car starts and you let go of the key, the ignition switch snaps back to the "run" position. When it's in this position, it sends 12V to the ballast resistor which in turn sends approximately 9V to the coil. Your switch appears to be perfectly normal.

As far as a key is concerned, if you are looking for a spare key, I would take the original key and ignition switch to a local locksmith and ask him to make one up for you.

Hope this proves helpful to you.

[stugilmour]

Thanks for the info Frank.

Seems like Frank is referring to the ballasted coil setup that shows in my Plus 2 workshop manual wiring diagrams on diagrams M82 and M86 only. I had not looked at these carefully before, and did not understand the ballasted coil requires the solenoid to make it work; helps a lot.

My car follows the non-ballasted coil set-up. The Plus 2 diagrams and original wiring show no interaction between the positive coil supply wire and the solenoid. The coil is only supplied by one wire that essentially comes from the ignition key through the anti-theft switch. This set-up appears to be the same as the Elan Series 4 Negative Earth diagram on page 116 of Gordon Lund's restoration guide.

From Frank's post, I am wondering if the ignition key switch assembly in my car got replaced with one that is actually for the ballasted type coil, but the solenoid and wiring were not changed at the same time?

Does anyone with the non-ballasted coil set-up know if the run terminal on the ignition key switch is hot in "start" position as well as the "run" position?

Looking at my post I see I wasn't clear regarding the 'key'. I was wondering about a call-up or p/n for the entire ignition key switch assembly, assuming mine is incorrect or pooched, rather than replacing just the key for the existing switch.

Thinking (if I have it right) I could either
- change out the ignition switch assembly.
- change over to a ballasted coil and different solenoid.
- insert a relay into the wiring to provide ignition supply voltage when in the "start' position.

Thanks again. Any other ideas gratefully appreciated.

[paddy]

Thinking (if I have it right) I could either
- change out the ignition switch assembly.
- change over to a ballasted coil and different solenoid.
- insert a relay into the wiring to provide ignition supply voltage when in the "start' position.

Instead of a relay you could just put an appropriately rated diode between the "run" and "start" terminals of your ignition switch.

Alternatively (since the solenoid is itself just a relay) wire the coil to the "starter" side of the solenoid - although you should really include an inline fuse between the solenoid and the coil since the main +ve supply to the solenoid isn't fused.

Paddy

[Frank Howard]

wire the coil to the "starter" side of the solenoid

The Gustafson Super Starter comes with an extra terminal for just this purpose. The Super Starter feeds 12V directly to the coil during cranking.

[stugilmour]

Thanks for the ideas Paddy. Will check out the solenoid more carefully.

[rgh0]

On my S4 Elan the run position stays live when the key is turned to the start position to engage the starter solenoid.

I believe this was the same in the ballasted coil cars. The start postion just applied 12v to the coil when in the start position, over riding the 9v being applied via the run postion and the ballast resistor.

Fouling and wear in the ignition switch can cause the run position to drop out when moving to the start postion but this is not the intended design I believe

regards
Rohan

[alan71]

Can you buy just the switch part of the steering lock ignition switch or do you have to replace the whole thing?

Alan