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16 Posts
First post and happy to help when I can. I've ran across many issues as you ass have as a motorcycle owner but this one has me very puzzled. I am doing some minor restoration on a 1980 CB650 and after getting it running and road worth I have put about 200 miles on it give or take. I noticed the headlight wasn't working at all but all other lights and blinkers work fine. The healight (low and high beam) do not work at all. I checked voltage to the headlight plug and had battery voltage (12 volts at the time). With the meter on the back side of the plug, still reading 12 volts, I plugged the headlight in and immediately lost the 12 volts. Once I unplugged the head light plug from the head light, with the meter still on the back side of the plug, I read around 2 volts. After a while the voltage will climb back up to battery voltage but it's the same issue each time. Another odd thing I've noticed is that I don't read any voltage to the high beam lead that goes to the headlight plug at all. Sometimes if I'm checking the plug and reading battery voltage, I will cycle the high/low beam handlebar switch and all the sudden the voltage drops off from battery voltage to 2 volts or random voltage.
I have taken the low/high switch off of the handlebar, inspected it, cleaned it and checked it with an OHM meter and it checks out ok. It seems to me that the switch is a very simple set of "pot switch" style contacts and they appear to be working so I don't think the issue is the switch but I'm all ears.
I wasn't 1000% convinced that the switch was working properly so I started taking voltage from the plug that enters the headlight housing from the main wiring harness. Taking voltage from this plug would bypass the low/high switch and tell me if the issue is coming from the main wiring harness or if it down stream like the low/high switch or head light or harness on that side. I am reading the same voltage drop off from the main plug on the main wiring harness that feeds the electrical into the headlight housing. I used two fuses in order to plug my power side and ground side into the main wiring harness plug. I used alligator clips to clip onto the fuses and my meter leads and I read battery voltage which was around 10.5v at the time (this was a week or so later). With my 10.5v power going from the main plug to my meter, I tried hooking it directly up to the head light and the voltage dropped out. Once I took the leads away from the headlight the voltage came back up to about 2.5 volts and started slowly climbing.
So, I'm assuming I have some part or something partially shorted??? I'm all ears and I'm a professionally trained technician (mechanical/electrical) but I figured someone might have seen something like this before. I thought I saw a capacitor behind the seat which is going to be the next thing I look at but before I start buying components online and guessing at the thing until its fixed does anyone have any input?
Sorry for the long post and thank you very much in advance.
I have taken the low/high switch off of the handlebar, inspected it, cleaned it and checked it with an OHM meter and it checks out ok. It seems to me that the switch is a very simple set of "pot switch" style contacts and they appear to be working so I don't think the issue is the switch but I'm all ears.
I wasn't 1000% convinced that the switch was working properly so I started taking voltage from the plug that enters the headlight housing from the main wiring harness. Taking voltage from this plug would bypass the low/high switch and tell me if the issue is coming from the main wiring harness or if it down stream like the low/high switch or head light or harness on that side. I am reading the same voltage drop off from the main plug on the main wiring harness that feeds the electrical into the headlight housing. I used two fuses in order to plug my power side and ground side into the main wiring harness plug. I used alligator clips to clip onto the fuses and my meter leads and I read battery voltage which was around 10.5v at the time (this was a week or so later). With my 10.5v power going from the main plug to my meter, I tried hooking it directly up to the head light and the voltage dropped out. Once I took the leads away from the headlight the voltage came back up to about 2.5 volts and started slowly climbing.
So, I'm assuming I have some part or something partially shorted??? I'm all ears and I'm a professionally trained technician (mechanical/electrical) but I figured someone might have seen something like this before. I thought I saw a capacitor behind the seat which is going to be the next thing I look at but before I start buying components online and guessing at the thing until its fixed does anyone have any input?
Sorry for the long post and thank you very much in advance.