Author Topic: CAR ELECTRICIANS ADVICE WANTED  (Read 1151 times)

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Offline HoraceM22

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CAR ELECTRICIANS ADVICE WANTED
« on: Friday,August 02, 2024, 09:59:33 AM »
Evening all,
I've just been trying to get my Hazard Warning Lights to function on my '74 TCS.
I have one of the round pull-on type switches with the red triangle on the knob and 7 terminals on the backside, 1 power in and nominally four out - one to each corner and two unused, but this has been wired using only two live wires. Probably didn't have them in the US.

I've got 12v to the relay, 12v from that to the switch and when pulled (switched) on 12v to each of the indicator bulb holders, but no flashing.
Any ideas as to what might be happening here.
All the best from the sunny UK - at the moment.
HoraceM
HoraceM22

Offline Dilkris

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #1 on: Friday,August 02, 2024, 10:12:30 AM »
Welcome!
Any chance of providing any pictures?
A picture speaks a thousand words as they say.   

Offline BDA

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #2 on: Friday,August 02, 2024, 10:18:23 AM »
Some of the guys have trouble with posting pictures because of their size. There are several ways of fixing that so you can successfully post your pictures.

The "official" method is explained here (https://www.lotuseuropa.org/LotusForum/index.php?topic=1379.0).

Another way is explained here (https://www.youtube.com/watch?v=O_55eg00H-w). This is for Windows but Macs have a similar tool and you can search youtube for "snipping tool apple" to find videos on it.

Offline Kendo

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #3 on: Friday,August 02, 2024, 11:08:11 AM »
The flasher unit needs a certain minimum current to work. For instance, some people who replace the flasher bulbs with LEDs can't get the flashers to cycle. Sometimes adding a resister to the circuit helps here.

So, I don't think the relays are stock. Tell me if I'm wrong. But if they are added, does the current draw on the relay's control side draw enough current to activate the flashers? If not, maybe here too a resistor would get things working properly.

Offline HoraceM22

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #4 on: Saturday,August 03, 2024, 03:35:34 AM »
The last bit was a bit technical for me but I do think that might be the way to look. I just need someone to guide me through it!!!!
HoraceM22

Offline BDA

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #5 on: Saturday,August 03, 2024, 09:04:14 AM »
I don't know your level of expertise so please don't be offended by my reply. Also, don't take my reply to imply I necessarily know a whole lot more about electrical systems than what I say  here!

One of the unfortunate realities of owning old cars is the existence of DPOs (dreaded previous owner realizing that I will be the DPO to whoever buys my car). They love to monkey with the wiring to the consternation of subsequent owners. Judging from your pictures, we have hope that yours is not mangled since your wire colors are correct and you still have the wiring tape on some of your wires. a DPO would not likely use wiring tape.

You are using a non standard switch so you'll need to "translate" your switch to the stock switch - in other words, wire it so it does the same thing. Judging from your initial post, it appears that you understand that. I assume the relay you mentioned is the DB10 unit that is labeled "RELAY" in the attached wiring diagram snippet. It is a rectangular box about 4"x2" behind the dash.

Do your turn signals (indicator lights) work correctly - they flash at the proper time? If so, it could be that your hazard flasher doesn't work. You can swap your indicator flasher for your hazard flasher to test that. If your problem moves with the flasher, that's your problem. If not, you can probably ignore (most of) the rest of this post as it sounds like your switch is wired incorrectly. In either case, bookmark http://lotus-europa.com/manuals/ as it has a lot of essential as well as interesting information about your Europa including searchable manuals and color wiring diagrams.

Kendo's suggestion that you may have LED lights in your turn signals is another thing to check. What he meant to say, I think, is that stock flashers (which you have as shown in your third picture with the purple wire) are mechanical and work with a bimetallic strip. The current draw from the turn signal's incandescent bulb heats up the strip causing it to bend and break the connection, the strip cools and bends back causing it to hit the contact which is the clicking sound you hear, the turns signal lights light up again which causes the bimetallic switch to heat up again and the process continues... LEDs don't draw enough current to heat up the strip so you either need to add resisters inline with your turn signal lights or get an electronic flasher (I recommend the former. Electronic flashers are either silent or they beep rather than click. I've gotten used to the beep! ;) ). They are usually available from automotive LED light suppliers. So as Kendo suggests, if you have LEDs, you won't get flashing but your lights should just stay on. That's easy enough to confirm by opening up your turn signal lamps and looking at the "bulb." 

Kendo also makes a good point about your relay - that it might not be stock and you may have a DPO problem (wiring that may need to be corrected) - but I don't think the relay will affect the current across the flasher as the relay will be either switched or not (I'm happy to be convinced otherwise, see second sentence of this post). Solid state DB10 replacements are available from Moss Motors and likely any parts supplier for older (British) cars.

Hopefully that helps! If it doesn't, maybe you can supply more symptoms or evidence.

Good luck!

Offline dakazman

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #6 on: Saturday,August 03, 2024, 06:17:32 PM »
  BDA made good points on a few concerns, another is to watch the orientation of the relay mounting.some people flip it over and some follow a few bad schematics drawn up.
 Another sore spot all the connectors beneath the steering column (black in color) and easily disconnected.
Dakazman

Offline HoraceM22

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #7 on: Sunday,August 04, 2024, 10:41:55 PM »
Cheers for those detailed suggestions BDA.
Over the weekend I checked for continuity for each of the wires from the switch to the four corners and from the earthing point (grounding, I think you call it) to the inside of each of the light units and all were giving a connection. I also checked for voltage at the bulb wire within the units and when switched it showed 12.5v on all four.

This is a restored car and has a "new" wiring loom (and everything else from the galvanized chassis upwards) and looking at the general condition of all the wiring I'd say a great job has been done. One of the UK specialists told that these cars didn't have a hazard warning switch fitted as standard, (although another said there should be a rocker switch on the dash, but having looked at several on sale here, none of them showed this switch, so I think he was on the wrong car in his head!) However, I'm also told that this pull switch, a genuine Lucas part No 155 SA, was a regular fitment as an addition to cars at the time. Strangely, the wiring does come out of the wrapped loom and looks as though it was always a part of the original wiring. No trailing wires as you might expect. Well, not for this item anyway!

It's one of those strange things - or not so strange in the old Lotus world - where you have the right wiring going to the right places with the right voltage and the switch switching and the relay apparently fine - a swap for a new one didn't make any difference, but no flashing. Grrrrr.
HoraceM22

Offline BDA

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #8 on: Monday,August 05, 2024, 07:48:14 AM »
The stock hazard switch was a rocker switch as you can see from the owner's manual (http://lotus-europa.com/manuals/tcowner/index.htm - did you bookmark http://lotus-europa.com/manuals yet?). Admittedly, the TCS owner's manual is for Federal cars but I doubt the Brit cars used different switches. I guess the question might be if the UK required a hazard switch. The wiring diagram for non Federal TCs shows a hazard switch so I'm pretty sure your car originally had one and it would be a rocker. Remember also that 1974 was before the standardization of the hazard switch with the triangle symbol on it. Of course, the dash is certainly not immune to people changing them and yours may now support your pull-out switch.

I have to ask, what exactly is the symptom you're experiencing? Do the turn signals (indicators) work but the hazard flashers don't? Or do are the turn signals not working either? Do the lights you expect to blink not light up at all or do they come on and stay on? Since you're getting 2.5v at the bulb would mean that the bulbs are illuminating. Are they incandescent bulbs?


Offline SilverBeast

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #9 on: Monday,August 05, 2024, 02:51:18 PM »
UK didn't have the hazard lights (or DB10 relay)

Offline BDA

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #10 on: Monday,August 05, 2024, 04:03:41 PM »
The UK TCS didn't have a hazard switch or a DB10???!!!

I can understand the hazard switch since that is extra cost but the DB10?

Interesting...

Thanks for the info, SilverBeast!

Offline jbcollier

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #11 on: Monday,August 05, 2024, 09:45:03 PM »
DB10 was only needed to meet US regs that prohibited separate brake and turn signal lights.  Stupid reg based on problems from the dawn of the motor car.

Offline jbcollier

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #12 on: Monday,August 05, 2024, 09:49:42 PM »
The hazard switch with the round knob is standard fitment in the kit to fit emergency flashers to cars that didn't have them.  It comes with a hazard flasher and a harness.

Exactly what do you have?  Photos as well, please and thank you.

Offline jbcollier

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #13 on: Monday,August 05, 2024, 09:53:58 PM »

Offline jbcollier

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Re: CAR ELECTRICIANS ADVICE WANTED
« Reply #14 on: Monday,August 05, 2024, 09:55:39 PM »
Connections as follows:

Purple - Live feed (with 30 amp in-line fuse)

Black - Earth

Green/White - RH indicators

Green - LH indicators

Green/Purple x 2. Cut existing feed of indicator relay on vehicle and connect either end of cut cable to one of the green/purple wires. This has the result, that when the SFB300 hazard switch is operated, it will cut the supply to the existing indicator relay.