headlamp relay control

[brianw]

Neil,

As per my earllier post when you first raised this point, this was one of the things I had checked before coming to my current conclusion.

When the headlamp switch is on, the lights are set for dipped beam and the pods are down, there is a voltage reading on both relay earths (since they share the same route to earth).

The problem goes away, if you break the circuit at the main beam warning light or indeed any of the other relay terminals. I assume the most telling point is that the main beam warning light glows faintly all the time the lights are on dipped beam, thus proving that this circuit is permanently live, albeit not enough to fully light the bulb.

Brian.

[neilsjuke]

If you have battary voltage on the earths to the relay then they are not earthed and this would cause the fault and i would remove the relays and test on the bench this will help you get the wiring of the relays clear in your mind and also will tell you if the points in the relay are ok and not welded together due to the wrong type fitted.
Neil

[garyeanderson]

If you have battary voltage on the earths to the relay then they are not earthed and this would cause the fault and i would remove the relays and test on the bench this will help you get the wiring of the relays clear in your mind and also will tell you if the points in the relay are ok and not welded together due to the wrong type fitted.
Neil

I guess I don't have any of these issues as the black/red is hard wired to ground. If I forget to turn off the lights when I push in thhe vacuum light switch, shame on me. The other part of the circuit, the headlamp flasher relay has also been left out. Its illegal in the U.S. to use flashing headlamps unless you are an emergency vehicle (cop, ambulence, fire, emt, etc). Besides in Massachusetts no one would pull over anyway, they would just assume your just another MassHole in a hurry to get no where.There is no lane discipline and folks drive in any lane they feel comfortable in.

Gary

[brianw]

Neil,

The relays are fine. To test them, I swapped over the main and dipped beam relays - same problem. Then I switched them for the horn and headlamp flasher relays - same problem. To me that is pretty conclusive that the relays are good - they can't all 4 be faulty, especially since for the most part the lights etc work fine.

I am also pretty clear about the relay wiring, since at different times I bypassed the dip switch as well as the individual live feeds from the dipswitch to the dipped and main beam relay terminals (thinking there might be some sort of crossover somewhere in the loom). None of this had any effect on the problem until I disconnected the main beam warning light.

I then checked the relay earths. When the dipped beams remain on with the pods down (i.e. in error), there is a voltage reading on the shared earth cable. However, at this point they are not earthed, since the micro switch is closed (i.e. the switch is effectively off) and the normal route to earth is incomplete. Only when the pods are raised, which reverses the switch (i.e. turns it on), and the proper earth connection is made does the voltage drop to almost zero.

All of the above convinces me Alex is correct in what I believe to be his original diagnosis. When the dipped lights are correctly on, the earth is made across the dipped beam relay via the micro switch to earth on the chassis. When the pods are lowered, the micro switch breaks the earth but an alternative route to earth via the shared earth cable across the terminals of the main beam relay and back up the live main beam feed to the point where the (gently glowing) mai beam warning lamp is earthed on the back of the tacho. Thus the dipped beam relay remains in the on position.

I am sure I have not described this in correct electrical terms, but I think the rationale is correct and moreover it seems to explain the problem, which disappears when this unintended route to earth is broken.

Brian.

[alexblack13]

Hi All / Brian
The flasher circuit is also a pain if you fit the st'd flasher unit as per diagram. It also does not work. The flasher does not have enough current passing thro' it for it to heat up and flash. This was to be my next mod. Looks like salvation has come my way this time, although I thought about linking it into the live feed to the relay I admit I had not tried it yet. I will soon though.

Any problems with the load of the headlamps over the little flasher unit? I can't remember the wattage of the device.

I think the black red wire up near the thermo' housing is a federal car system that is in all the looms from Autosparks. (Mick would have used this loom) It is for a brake fail/level sensor thingie (never seen one!). I just cut it out of the loom That was b4 I had the ''fun'' with the headlamp relays

Great laugh these cars eh ??

Have fun..But not toooo much at once.

Alex B

[brianw]

Hi Alex,

I joined blue/purple and yellow/blue at the point where the diagram shows the flasher unit. Then I connected the flasher inline to the blue/yellow that feeds the flasher relay.

To be honest, I didn't worry too much about the load at that point, since I thought I was tapping into the feed to the relay and not the bulbs, but as I am sure you are aware the blue/yellow feeds both input terminals on the relay.

In practice it seems to works fine, since nothing has gone up in smoke yet. In any event, it is something that will get little use if ever. I really only fixed it to make the car as "complete" as it was meant to be.

Cheers,
Brian.

[alexblack13]

Hi Brian/ All,
Yes I linked the feed also on that relay.Only three cables going to it. I will wire the flasher into the line as you suggest and wait for the smoke.. LOL....

Only joking That should work just fine. How fast does it flash?


Alex B

[brianw]

Alex/All,

It flashes at more or less normal flasher speed ... between 1-2 times per second I would guess.

The spare red/black solution for the main beam warning light works perfectly too. Shame the end isn't a bit longer so it would connect direct to the relay, but a short insert of cable to piggy back on the terminal with the blue/white feeding the main beams is no hardship.

The other end of the red/black terminates behind the speedo and will just reach the blue/green for the warning light. Connect it all up and ..... EUREKA ..... main beam warning light is only ever on when the main beams are actually alight and dipped beam is never left on when the pods are down!

Thanks to all for the help with this. Colin Chapman can rest easy in his grave knowing we sorted out a little wiring problem for him.

Brian.