Curious headlight switch behaviour?
Posted: Sun May 22, 2022 7:30 am
Hi everyone
I’ve posted elsewhere on this forum about ongoing trials of fitting what seems to be a 130 loom to a SE car, but have been making progress.
My current problem is as follows.
I’ve been trying to figure out the wiring for the headlights. Starting with the dipped circuit.
I have a light switch that combines the micro switches with the vacuum control.
Currently, if I twist the light switch slightly the sidelights come on
If I pull the knob out, the sidelights stay on but nothing else happens, no dipped beam.
Checking the wiring for the dipped beam relay, the switched supply is fine 12v live all the time, the switching supply takes its 12v feed from the live switched supply (blue/white) and seems to then use a switched earth to then trigger the relay to activate the headlights. So if I short the switching supply and earth the pin, the headlights activate and the relay closes.
The switched earth seems to be a black/red wire in the engine bay which I assume would have connected to a micro switch on the drivers side light pod. My car doesn’t have this switch there, with the micro switch on the light switch unit it seems. And indeed when I pull the light switch out two of the contacts on the lower light microswitch have continuity. So simple I thought. Just run a new cable to the black/red switched earth in the engine bay to the micro switch so that when I pull the light knob, the relay is triggered and the dipped beams come on….but nope.
If I have the sidelights on (or off) and pull the knob, the switching supply is not earthed to activate the relay and dipped beam. If I disconnect the black/red cable from the microswitch and earth it manually, the dipped lights come on. Anyone have any ideas about why when I connect then black/red and an earth to the microswitch, I don’t in fact earth the switching supply? It seems very odd to me.
Pics to flow btw!
Thanks
Ian
I’ve posted elsewhere on this forum about ongoing trials of fitting what seems to be a 130 loom to a SE car, but have been making progress.
My current problem is as follows.
I’ve been trying to figure out the wiring for the headlights. Starting with the dipped circuit.
I have a light switch that combines the micro switches with the vacuum control.
Currently, if I twist the light switch slightly the sidelights come on
If I pull the knob out, the sidelights stay on but nothing else happens, no dipped beam.
Checking the wiring for the dipped beam relay, the switched supply is fine 12v live all the time, the switching supply takes its 12v feed from the live switched supply (blue/white) and seems to then use a switched earth to then trigger the relay to activate the headlights. So if I short the switching supply and earth the pin, the headlights activate and the relay closes.
The switched earth seems to be a black/red wire in the engine bay which I assume would have connected to a micro switch on the drivers side light pod. My car doesn’t have this switch there, with the micro switch on the light switch unit it seems. And indeed when I pull the light switch out two of the contacts on the lower light microswitch have continuity. So simple I thought. Just run a new cable to the black/red switched earth in the engine bay to the micro switch so that when I pull the light knob, the relay is triggered and the dipped beams come on….but nope.
If I have the sidelights on (or off) and pull the knob, the switching supply is not earthed to activate the relay and dipped beam. If I disconnect the black/red cable from the microswitch and earth it manually, the dipped lights come on. Anyone have any ideas about why when I connect then black/red and an earth to the microswitch, I don’t in fact earth the switching supply? It seems very odd to me.
Pics to flow btw!
Thanks
Ian