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# Want to understand

#### jakub89

##### New Member
Hello everyone I'm new to the forum and I just start my electronic journey so I’m gonna ask easy/obvious questions (not for me). Hope to learn basic and who knows what else. So if you can help me to understand those things gonna highly appreciate it, maybe one day I will be able to pass knowledge to someone else. End of introduction myself so my case is about this diagram:

I would like to understand current flow of this car headlight wiring as want to solve the problem in same time. In this case when I switch to ON low beam lights doesn’t works at all, but high beam works. Please correct me if I get this wrong. This orange arrows represent my vision how current flows when switch is in off position

I have done reaserch and what I find out so far it's Combination light stalk that is connected to combination light switch. issue with earthing. My idea was to bypass circuit to make it works like blue arrows shows:

Let me know if :

a) my understanding of this is correct/ totally wrong (if so why)
b) bypass gonna works
c) how to include earth (pin 12) to make it works

And first of all sorry for bad drawing, was doing it from my tablet. Thanks in advance for any interesting and constructive criticism

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Last edited:
From the diagram, the only difference between low and high is the dip/full switch, at the left of the combination switch block.

Is there voltage on pin 6 when the headlights are on, high beam?
I would check for loose or corroded connections & broken wires before doing any modifications.

If there is voltage on pin 6 (with the meter negative on a chassis screw or clean metal), does that go to near 0V when you select low beam. If it does and the low beam does not come on, the fault is external to the switch. If the voltage stays around 12V, the fault would appear to be within the switch.

Just linking pin 6 to 7(?) is not a good idea, as the headlamp flash switch (2nd section of the combi switch) will ground that through the diode, which is only intended to carry the relay coil current. The actual lamp current is much higher - it will almost certainly blow that diode, and may wreck the switch if the contacts and internal connections are not big enough.

I concur with JRW.

Did you put the lamp option switch in the correct position? (see diagram) {Ξ(>}

I didn't see any mention of checking the bulbs to see if the low beam elements have burned out. Maybe I missed it.

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