S2 tail/stop lights

[StephenT]

I’m trying to get some wiring sorted out on my car. Right now I don’t have any lights functioning in back. A big help would be to know what is the correct function of each light. My car has a single filament bulb in the outboard position and a dual filament bulb inboard. But I don’t know which bulb is brake, tail or blinker. I did notice on the dual filament bulb that one filament is brighter than the other.

Thanks,
Steve

[Elanintheforest]

Steve, the single filament is the indicator, and the double is the stop light and rear light.

Check the cable colours to see which is stop and which is rear light. Most Brit cars use the same Lucas standard.

Also check the earth connection for the lights. With an Elan, if something electrical doesn't work, the earth is usually to blame!

Mark

[StephenT]

Thanks Mark

The wiring for the entire car is a bit of a mess. In the boot/trunk area a po has abandoned the original wiring harness and run additional wires from under the dash to the rear (none of which seem to work).

My first goal is to resurrect the brake lights. I know the brake light switch is bad so that will be replaced. When I tie the two wires together at the brake light switch I get a very dim glow from the two bulbs on the right hand side of the car.

Thanks for the chart hopefully it will help in sorting this mess out. And I will make sure I have decent ground back there.

Steve

[StressCraxx]

One word: grounds. Check remove, clean and remake each one.

[StephenT]

I’ve been working on the lights and have made some progress but still having issues. I have discovered that the brake light switch is bad and ordered a new one. Is there a way to change the brake switch without having to bleed the brakes afterwards?

I have the tail lights working but there is an odd issue when the tail lights come on I get a very dim glow from the right signal light. Also when diagnosing the brake light switch and I shorted the two tires at the brake switch together the right signal light came on then as well. Any idea where these two circuits can intersect?

Thanks,
Steve

[khamai]

Brake light switch can be replaced without having to bleed brakes. I saw this done by Barry Spencer, amazing...

Have your replacement at the ready, have an assistant put very light pressure on the brake pedal. Now, loosen the brake light switch and remove and quickly replace with the new switch. Some brake fluid will squirt out and the job will be somewhat messy. But no air will be allowed into the system if kept under pressure.

Cheers,
Kiyoshi

[StephenT]

It sounds reasonable, and a little messy. I had actuality thought of trying this but as my wife will be my assistant (begrudgingly) I’m not sure if she understands the concept of “light pressure”. She could also take the opportunity and dump the petal just so I never ask her to help again.

Thanks, Steve

[StressCraxx]

As Kiyoshi noted, very light pressure, just taking up the slack helps displaces a little fluid. The other thing I noticed was Barry filling the port of the switch just before fitting. I think he used a little dropper so there's no air in the fluid side of the switch.

[StephenT]

That’s a good idea. I just looked at the switch and there is more volume inside the switch than I anticipated that could introduce air into the brake lines. I will definitely fill it with fluid prior to installation.

Steve

[gjz30075]

I've used a board between the front of the seat and the pedal, when bleeding by myself. It should
work for your situation, too. The length of board I used was for hard pressure. I'd imagine a slightly
shorter one for light pressure.

[joe7]

Make sure to get a new crush washer.

[StephenT]

I did get the crush washer with the switch.

Followed the suggestions above and was able to install the new switch without filling the brake lines with air or covering myself in brake fluid. The switch is functioning perfectly now if I could only figure out what is going on with the wiring.

What I am about to describe sounds impossible because it is impossible but this is what I am experiencing. A previous owner ran a wire from the front right signal light to the right rear signal light and spliced into the right signal wire on the steering column. When I activate the turn signal lever the front light flashes, the rear does not. Here is the good part. When I step on the break the front and rear right signal lights come on. The brake light does not come on. I have traced the po wire its entire length (every inch) there is no place where another wire ties into it. When I disconnect the wire from the signal switch on the column the lights are still activated by the break. Somehow the signal from the break switch is connected to the signal wire but I can not figure out how.

[saildrive2001]

Check all ground connections, strange things happen with the Elan when there is a bad ground, been there seen that.

[mbell]

The federal cars have a DB10 relay block to allow re-use of tail lights as indicators. My guess is your issue is related to that.

[Craven]

A clue to an earth fault is the brightness of the bulbs, you say the various lights work but are they at full brightness, is the flash rate correct? No DB10 on an S2