A bit of a long story, but I thought this might be very helpful for somebody else that is having similar problems. This took me hours and hours of troubleshooting to find a solution.
The original problem was that headlight filaments were burning out separately and randomly. I would replace the bulb with a new one and the bulb would last a couple of hours, a day, a week. Sometimes the low beam would burn out and the high beam would be fine for weeks (or vice versa) but would eventually burn out. The tail light never burned out. Google said 99.9% of light burnout problems originate with the voltage regulator. There is no rectifier on this machine.
The original voltage regulator (regulator #1) that was in the machine was a 1-wire regulator. The yellow wire from the regulator connected with the yellow wire on the harness in a three blade plug connector. An independent ground wire was connected from the regulator mounting bolt to the three blade plug connector, but not in the correct position in the plug to make connection with the corresponding yellow black wire in the harness. Essentially, this gound wire was connected to nothing. However, the voltage regulator is grounded through the regulator casing to the frame of the machine.
The obvious solution in my mind and in 99.9% of the Google searches I did was to replace the voltage regulator.
A new two wire universal regulator (regulator #2) was installed and wired exactly as the original, with the exception of the black wire on the new voltage regulator was wired directly to ground at the attachment point of the regulator and the yellow wire was connected to the yellow wire on the harness. A separate ground wire was installed from the new regulator mounting bolt to the plug on the wiring harness and still connected to nothing in the plug casing. The random burnout of the headlights was still happening. I was advised that a short somewhere in the harness could cause random burnout of the headlight filaments.
The wiring harness was removed and two chaffed wires were located in the harness underneath the seat. This was repaired and the machine was started. It was immediately noticed that the headlight and tail light beams now were glowing in intensity with engine rpm until both lights burned out as opposed to randomly burning out only the headlights.
This is now an entirely new problem but with more classic symptoms of a faulty regulator. A new universal 2-wire regulator (regulator #3) was installed exactly like the second 2-wire regulator. The result was the same. As the rpm increased, so did the intensity of the lights until burnout occurred. I found in a forum a post regarding a 2-wire regulator for a 1990 Citation stating that the black wire on the 2-wire regulator should not be connected to machine ground but to harness ground. I mentioned earlier that the ground from the regulator to the plug on the harness was connected in the plug to nothing. I switched the blade from the ground wire in the plug to the slot so that it now connected to the black/yellow wire on the harness. Now the regulator was connected to the harness with yellow from the regulator to yellow on the harness and black on the regulator to black yellow on the harness.
Please note that when the ground from the 2-wire regulator (regulator #2) was, at an earlier point, actually connected to the black/yellow wire on the harness through the plug connector, an immediate burnout occurred to all the lights. This was before the shorts were found under the seat.
It was a real puzzler. I was advised that a short could possibly burn out a regulator, so once the shorts were repaired and the 2-wire regulator (regulator #2) wired correctly I still had a classic bulb burnout condition as if the regulator wasn't working.
Amazon to the rescue with a new universal 2-wire regulator (regulator #3).
Now, with the shorts fixed and the new regulator black wire to ground on the harness and the yellow regulator wire to yellow on the harness, the problem was solved. I now have nice steady headlights with no burnout.
The original problem was causing the headlights to randomly burn out because the chaffed wires under the seat only shorted when the bare wires were in contact with the metal seat deck from weight from the rider and bumpy rides.
This explains the randomness of the burnouts.
Total expenditures:
10 headlight bulbs
2 voltage regulators
Copious amounts of alcohol 😂
I hope this helps someone because it sure would have helped me in the beginning of my troubleshooting with this weird problem.
The original problem was that headlight filaments were burning out separately and randomly. I would replace the bulb with a new one and the bulb would last a couple of hours, a day, a week. Sometimes the low beam would burn out and the high beam would be fine for weeks (or vice versa) but would eventually burn out. The tail light never burned out. Google said 99.9% of light burnout problems originate with the voltage regulator. There is no rectifier on this machine.
The original voltage regulator (regulator #1) that was in the machine was a 1-wire regulator. The yellow wire from the regulator connected with the yellow wire on the harness in a three blade plug connector. An independent ground wire was connected from the regulator mounting bolt to the three blade plug connector, but not in the correct position in the plug to make connection with the corresponding yellow black wire in the harness. Essentially, this gound wire was connected to nothing. However, the voltage regulator is grounded through the regulator casing to the frame of the machine.
The obvious solution in my mind and in 99.9% of the Google searches I did was to replace the voltage regulator.
A new two wire universal regulator (regulator #2) was installed and wired exactly as the original, with the exception of the black wire on the new voltage regulator was wired directly to ground at the attachment point of the regulator and the yellow wire was connected to the yellow wire on the harness. A separate ground wire was installed from the new regulator mounting bolt to the plug on the wiring harness and still connected to nothing in the plug casing. The random burnout of the headlights was still happening. I was advised that a short somewhere in the harness could cause random burnout of the headlight filaments.
The wiring harness was removed and two chaffed wires were located in the harness underneath the seat. This was repaired and the machine was started. It was immediately noticed that the headlight and tail light beams now were glowing in intensity with engine rpm until both lights burned out as opposed to randomly burning out only the headlights.
This is now an entirely new problem but with more classic symptoms of a faulty regulator. A new universal 2-wire regulator (regulator #3) was installed exactly like the second 2-wire regulator. The result was the same. As the rpm increased, so did the intensity of the lights until burnout occurred. I found in a forum a post regarding a 2-wire regulator for a 1990 Citation stating that the black wire on the 2-wire regulator should not be connected to machine ground but to harness ground. I mentioned earlier that the ground from the regulator to the plug on the harness was connected in the plug to nothing. I switched the blade from the ground wire in the plug to the slot so that it now connected to the black/yellow wire on the harness. Now the regulator was connected to the harness with yellow from the regulator to yellow on the harness and black on the regulator to black yellow on the harness.
Please note that when the ground from the 2-wire regulator (regulator #2) was, at an earlier point, actually connected to the black/yellow wire on the harness through the plug connector, an immediate burnout occurred to all the lights. This was before the shorts were found under the seat.
It was a real puzzler. I was advised that a short could possibly burn out a regulator, so once the shorts were repaired and the 2-wire regulator (regulator #2) wired correctly I still had a classic bulb burnout condition as if the regulator wasn't working.
Amazon to the rescue with a new universal 2-wire regulator (regulator #3).
Now, with the shorts fixed and the new regulator black wire to ground on the harness and the yellow regulator wire to yellow on the harness, the problem was solved. I now have nice steady headlights with no burnout.
The original problem was causing the headlights to randomly burn out because the chaffed wires under the seat only shorted when the bare wires were in contact with the metal seat deck from weight from the rider and bumpy rides.
This explains the randomness of the burnouts.
Total expenditures:
10 headlight bulbs
2 voltage regulators
Copious amounts of alcohol 😂
I hope this helps someone because it sure would have helped me in the beginning of my troubleshooting with this weird problem.
