Lotus Elan

S4 New Harness Wiring

PostPost by: 0005K » Fri Apr 13, 2018 3:40 pm

I am in the process of a total rewiring of my S4 Federal Elan with 3 new harnesses from British Wiring. I am having difficulty (so far) with the fail-safe headlamp switches, the hazard switch, and the relay(s). The old dash harness was of little use, as it was from an S3 - not the original which had melted. The S3 dash harness had been modified in several areas (and the car now has been off the road for nearly 40 years).
I have expanded and printed out one of the excellent redrawn color coded CAD recreations of the S4 schematic found on this site.
My hazard flasher rocker switch is on center-line of the dash panel. It has 5 lugs for wiring attachments, but the melted wires attached to it tell me little of what goes where. The schematic (and new harness) seem to show the hazard switch outboard of the steering column (and not what color goes to what lug).
It also has a two-lug cylindrical relay (W1 to a body plunger switch via white/green, and C1 to the top lug of the dash rocker headlamp switch). It also has a 3 lug box relay attached to blue/white and green/white, and ? And there is another item which may be a 3+ lug voltage stabilizer attached to two green wires and a ground.
I suspect I'll eventually get there, but assistance may help me speed things up.
Thanks
Dick
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PostPost by: William2 » Fri Apr 13, 2018 4:11 pm

Maybe a dumb question but if you purchased the cable assemblies from a UK supplier are you sure they include the wiring for fail safe headlights and hazard warning switches as these items were not fitted to UK spec cars.
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PostPost by: 0005K » Fri Apr 13, 2018 6:11 pm

Reasonable question.
I just called my supplier in USA British Wiring, and he said that the harness I purchased does attach to headlamp micro-switches. On fail-safe cars these two switches are on either side of the headlamp vacuum actuation switch. And there is another headlamp rocker switch to the right of it.
I was hoping someone had recently done this type of re-harnessing or could suggest the best schematic for sorting this out.
Thanks
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PostPost by: 1owner69Elan » Fri Apr 13, 2018 6:29 pm

"British Wiring", I believe is a US based company, in spite of the name.

I believe most of the various wiring harnesses, including those from British Wiring, are supplied from Autosparks (UK). https://www.autosparks.co.uk You will note that they use the same catalogue numbers.

As far as the specific questions that 0005K raised:

It appears that you have the hazard warning switch setup from a Sprint (or very late S4?). The federal S4 typically has a slide switch under the dash to the left of the steering column and hidden under the dash. It appears that your wiring harness is consistent with that. Perhaps you need the Sprint version? Or will have to modify the one you have?

Not entirely sure what the other items are on your harness that you refer to as being relays. When I recently rewired my Federal S4 (69) I don't recall any items like those apparently being included with your harness.

There are cylindrical relays for the turn signals and the hazard flashers but I used my existing ones (until I changed to LEDs and replaced them). There is also a rectangular voltage stabilizer (for the fuel gauge) attached to the back of the speedo or tach (don't remember which, would have to verify). Also there are the relays for the high/low beams and the horn. The color coding for the relays you mentioned doesn't seem to entirely make sense. Were the relays included and connected on your new harness or are you trying to sort through connections with existing relays/flashers?

I will say that the headlamp wiring for the push/pull vacuum switch in conjunction with the rocker switch (on-off/2 position) is quite specific to the Federal S4. None of the wiring diagrams that I could find really addressed this configuration appropriately. I finally got it right by studying what it was supposed to do, and some trial and error. I might have the final wiring in my notes somewhere. There are a couple of jumper wires between the vacuum switch and the rocker, not included with the harness. I had them from my original wiring.

Also, there is an instrument ground wire that was not included with my harness (I used those from my original wiring).

The other thing specific to the Federal S4 is a black/red headlamp switched ground wire that my new harness did not have that runs from the front of the car to the headlamp switch. I was able to use the existing one. Again, the wiring diagrams show a different setup for this black-red wire.
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PostPost by: 0005K » Fri Apr 13, 2018 9:22 pm

Thank you. Interesting that my January 1970 "K" model dash configuration appears to be more Sprint-like. The relays are what were on the car 40 years ago; not supplied with the new BW / Autosparks harness. The wire colors are what they were attached to on the used S3 (positive earth) harness which I cobbled-in semi-successfully, way back then. I will need to modify/add to this new harness to make it work. I need to compare the harness I have to an S4 Sprint wiring schematic (Anyone have a Link?). I have already found that some of the smaller "jumper" connections I may need are not on the harness I am installing.
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PostPost by: 1owner69Elan » Sat Apr 14, 2018 6:55 am

You might find the following wiring diagram for the headlights helpful, if you don?t have it already. Contributed by another forum member.

download/file.php?id=30867

As I recall I still had to work out the connections between the rocker switch and the micro switches on the vacuum switch.
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PostPost by: 0005K » Mon Apr 16, 2018 9:26 pm

Thanks.
I may need more info from you on where the black with red tracer goes. I have nothing I can find on the original melted harness or on the cobbled S3 harness.
I started rewiring with the new dash harness first, and it is challenging. I still have the engine bay and the boot to do. I am contacting harness supplier for direction on the dash harness items. I may end up leaving the hazard wiring for later.
Lots of other reassembly items for now...
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PostPost by: 1owner69Elan » Mon Apr 16, 2018 10:09 pm

The black wire with red tracer connects to one of the microswitches on the vacuum switch on the dash, with the "input" lug connected to ground. The BR wire connects to ground when the knob is pulled. (You may want to use a meter (or other connectivity tester) to ensure that the ground is NOT connected with the knob pushed IN, and vice versa, as there are two microswitch lugs that you can choose - NO (normally open) and NC (normally closed)).

This BR wire then runs through the firewall to the front of the car to the headlight relays (as shown in the last diagram sent).

The difference with the non-federal cars, as shown on most of the wiring diagrams, is that the microswitch is in the front of the car on the non-Fed cars. The black/red wire thus emanates from there instead of at the dash.

So you need a long (dash to headlight relay) BR wire that won't be included with your harness. You can probably buy a Black with Red tracer wire from British Wiring. In fact, you should try to keep to the color coding throughout (which doesn't sound like what you started with).
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PostPost by: pharriso » Tue Apr 17, 2018 12:25 am

0005K wrote:Thanks.
I may need more info from you on where the black with red tracer goes. I have nothing I can find on the original melted harness or on the cobbled S3 harness.
I started rewiring with the new dash harness first, and it is challenging. I still have the engine bay and the boot to do. I am contacting harness supplier for direction on the dash harness items. I may end up leaving the hazard wiring for later.
Lots of other reassembly items for now...


That's the wiring diagram for Federal Failsafe lights that I put together. Full information is posted at http://www.lotuselan.net/forums/lotus-electrical-f38/late-federal-fail-safe-headlight-wiring-t30133.html

The extra Black/Red wire is shown in the diagram, from one of the microswitches to terminal W2 on both headlight relays & terminal W1 on the flasher relay. It was not in the original Lotus loom, but a seperate somewhat half assed addition by Lotus.
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PostPost by: 0005K » Wed Apr 18, 2018 6:10 pm

Great inputs on headlamp/relay/microswitch connections. I think I have a chance to get there with your input - and a continuity tester. I agree that added wires should be correctly color coded to prevent future confusion.
My original wiring was modified by adding an alarm by PO, and experienced a significant thermal event prior to my ownership. (Also it was connected to positive earth when I bought it!)

Can you point me in any direction for the centerline-of-dash hazard switch connection? When viewed from the rear it appears to have a green/red , melted, green/white on the top 3 lugs when viewed from the rear. The lower two lugs are bridged by the switch and have purple/blue and grey wire connections. I don't think grey was original, and the switch was never functional during my ownership. Are there any similar (Sprint, +2S, Europa, ?) schematics which may show typical wiring of the hazard switch?
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PostPost by: pharriso » Wed Apr 18, 2018 9:49 pm

From the Federal +2s 130 wiring diagram:

fedhazards.jpg and
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PostPost by: 0005K » Thu Apr 19, 2018 1:58 pm

Thank you Phil.
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