Non working and weird leccys

[pugwash]

Morning good people, I have a couple of questions about the electrics of the recently purchased 1981 Spitfire 1500. I appreciate that these questions have probably been covered before but I have not worked out the search system yet. So:

1) The hazard lights do not work - an MOT requisite here too - and of course the obvious suspect is the flasher unit which I have no idea how to get to. I would like to check the switch first but I cannot work out how to remove it.

2) When driving with the headlights on then sounding the horn the headlights dim substantially. Where will I find the gremlin?

3) I would like to change the indicator light to a brighter LED. The self cancelling does not work and the light is difficult to see especially in bright light with the roof down. Again I cannot work out how to remove the light to do the swap.

Any help will be gratefully received, thanks.

[JohnD]

First need to sort out electrics is a multimeter, or even just a test light, a 12V bulb on the end of a pair of test leads.     Use these to check how far the 12V (or so) volts from the battery are getting towards the components it should be energising.

Next, a circuit diagram.  You can buy a large one to mount on your garage wall if you like : https://www.ebay.co.uk/itm/324756588443 but there are lots to print out from the Web, including here: https://forum.tssc.org.uk/topic/9814-wiring-diagram-and-symbols/, or of course there will be one in your Workshop Manual!

All the wires are colour coded, with a key in the Manual, where the first colour is the main one and the second the stripe.   You can start either end, battery or flasher light, just follow the wires until you find the fault.

John

 

[Colin Lindsay]

The indicator warning light is in between the gauges and it may be that the best way to access the rear of it - if you can't lie upside down in under it due to room constraints - is to take out the centre section of the dash, then remove the nearest gauge. You may have long enough fingers to reach the bulb and pull it out but refitting it always requires more finger room. There are numerous LED bulbs available, I use the forward-facing versions on some applications, that just have the leds on the end and not the sides, but you can also replace the green 'jewel' with a more visible version; I did this for my Herald (in fact moved the light to a more visible spot on the dash). Another alternative is to add a small audible buzzer into the circuit which works regardless of the ambient light covering the dash indicator. 

The flasher unit is up behind the dashboard; some models have one, others a separate one for each of indicators or hazards. Use a mirror to locate it then pull it out of the bracket, or if you have a spare just connect the wires to the new one first to see if that cures your problems. If you have only one flasher unit the problem may be the hazard switch itself. 

I found this explanation on an American Spitfire site:

"The hazard switch has to disable the turn signals to work properly, so it has a set of contacts that make or break power to the turn signals. This is true whether you have the rocker style switch, or the push/pull type of switch. If you don't have power coming to the turn signals with the hazard switch off, the hazard switch is likely the problem. Bypass the hazard switch and check the operation of the turn signal switch. Jumper the solid green wire at the hazard switch to the light green/slate (grey) wire to send power to the turn signal flasher unit. This should feed the light green/neutral (brown) wire at the turn signal switch. If you don't have power at the turn signal switch you could have a bad flasher or a disconnected wire (note that there is a single connection between the flasher unit and the switch, probably under the steering column).

Test that power goes to front and rear lights through either the green/red or green/white wires, depending on the switch position. There are connectors on these wires under the column, at the multi-connector at the left kick-panel under the dash, and of course at each lamp.

Once you've tested the turn signals reconnect the green and light green/slate wires at the hazard switch. If the turn signals stop working, the hazard switch is at fault. (sometimes this can be fixed by operating the switch multiple times to clean the contacts. 

Now turn the hazard switch on and power should flow from the hazard flasher which is feed by a purple wire from the fuse which is hot even with the key or headlights off. Power comes into the hazard switch on a light green/pink wire and goes out of the switch on all green/red and green/white wires to flash all the lights and the light green/green wire to flash the hazard indicator. If you have the wires correctly hooked up at the hazard switch and there is power from the flasher, then the lamps should flash on all four corners unless the switch is bad. Again, operating the switch may fix connectivity problems in the switch.

If the turn signals work when you jumper the hazard flasher, but nothing works with the hazard flashers, you may have the hazard switch incorrectly wired. Not the numbers on the wiring diagram and compare them with the positions of the wires. Now locate those numbers on the back of the switch (you either need a mirror, a light, and really good eyes, or you need to pop the switch out of the dash. This is easiest to do when you open the center section of the dash and reach behind the instruments. Sometimes, you need to remove the gauge to access the switch and depress the tabs that hold the switch in place. 

Note that the Push/Pull type of switch has a pigtail with a molded plug, so incorrectly hooking up this type of switch is impossible unless your PO was a moron and cut the pigtail and rewired with single color wiring."

They also had this very nice wiring diagram; USA spec maybe but very clear and also free.

[pugwash]

1 hour ago, JohnD said:

First need to sort out electrics is a multimeter

Next, a circuit diagram.  You can buy a large one to mount on your garage wall if you like... of course there will be one in your Workshop Manual!

Multimeter: Check

Workshop manual with circuit diagram*: Check

Garage wall: Umm, I may have a problem. Residential flats with a communal garage.

 

* The manual is B&W so those links will be saved for future reference, many thanks.

[pugwash]

37 minutes ago, Colin Lindsay said:

The indicator warning light is in between the gauges and it may be that the best way to access the rear of it - if you can't lie upside down in under it due to room constraints - is to take out the centre section of the dash, then remove the nearest gauge. You may have long enough fingers to reach the bulb and pull it out but refitting it always requires more finger room. There are numerous LED bulbs available, I use the forward-facing versions on some applications, that just have the leds on the end and not the sides, but you can also replace the green 'jewel' with a more visible version; I did this for my Herald (in fact moved the light to a more visible spot on the dash). Another alternative is to add a small audible buzzer into the circuit which works regardless of the ambient light covering the dash indicator. 

The flasher unit is up behind the dashboard; some models have one, others a separate one for each of indicators or hazards. Use a mirror to locate it then pull it out of the bracket, or if you have a spare just connect the wires to the new one first to see if that cures your problems. If you have only one flasher unit the problem may be the hazard switch itself.

They also had this very nice wiring diagram; USA spec maybe but very clear and also free.

Very interesting and informative. I think if I am going to have the dash to bits to get at the indicator light and hazard switch/flasher I will put in an audible warning too, a great idea, I think modern motorbikes come with them as standard.

The car is Luxembourg spec so oddly closer to American and not the same as German. There are two separate flasher units if I have read up correctly. As the flasher unit only costs € 9 I will get one anyway and try bypassing the original, it will probably save time, temper and knuckles.

Why does that wiring diagram (also downloaded) make me think of the London Underground?