Headlight/high beam out on 85 FJ

[jscgdunn]

Great!  Radar Love....

[FJFAST]

Haha..an old Escort Passport that I just never got around to disconnecting for one reason or another. Worked well in its time. Haven't really looked in to the new stuff...I'm sure there's Bluetooth connectivity etc.

[FJFAST]

More work to do gentleman...lamp was
working but when set fairing back on and finished connections-no light or highbeam indicator. Didn't have time to go back over everything.   Dang it...soo close.   

[FJFAST]

The low voltage at the original headlamp connector has to lead back the connections that you have already checked. Start with the headlamp fuse on the left side fuse panel(at least on a 85) The body of the fuse has an indention on both sides of the top check and compare the voltage at both points with the headlamp plugged in and turned on. I expect them to be within one tenth of a volt. Using the same ground point for the meter measure voltage to the positive battery post. Are the three measurements close to the same? The path for the 12 volts is from battery to ignition switch to headlamp fuse to start switch to the high beam switch and last to the head lamp socket. Either at or between these points there is a high resistance which will carry the small amount of current to make the volt meter work but not allow the much higher current of the headlamp to pass through. This could be the stranded conductor being broken inside the insulation but when you are investing your time the more likely suspect is one of the switches or fuse socket.  The start switch and high beam switch contact surface must be clear of corrosion but each also has a spring that pushes the contacts together. Pushing against the spring tension can break the contact loose. The list of possibilities isn't long. Establish the last place that has full voltage and that will identify where to look for the problem. My Dad taught me to split things in half and then into small parts until you find the problem. Divide and conquer. I'm no rocket scientist and I can do it and have taught a few others. When my kids learned to read it looked so hard and they said "I can't do this", until it all made sense. Yes you can.

Chris

The low voltage at the original headlamp connector has to lead back the connections that you have already checked. Start with the headlamp fuse on the left side fuse panel(at least on a 85) The body of the fuse has an indention on both sides of the top check and compare the voltage at both points with the headlamp plugged in and turned on. I expect them to be within one tenth of a volt. Using the same ground point for the meter measure voltage to the positive battery post. Are the three measurements close to the same?

The voltage checks out on all three points from a ground point and also off th battery ground.


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I've got 5.5V coming into left switch and 5.5V coming out on low and high beam wires as well as at the end of the harness before the socket. Thoughts? I'm ready to say forget it and put it back together as is and deal with it later. Too nice out to be sitting around on a holiday weekend.

[FJFAST]

I've got 5.5V coming into left switch and 5.5V coming out on low and high beam wires as well as at the end of the harness before the socket. Thoughts? I'm ready to say forget it and put it back together as is and deal with it later. Too nice out to be sitting around on a holiday weekend.

[FJ1100mjk]

Too nice out to be sitting around on a holiday weekend.

Amen to that! Summer comes but once a year.

[FJFAST]

 

measure voltage from the low beam wire to the battery positive post - that will show the voltage drop across that circuit. The lower the voltage reading the resistance between the two points. Key on with the light switch in low beam position. Measure voltage across the two battery post ? 12 volts? Measure voltage from the positive post to a good ground on the frame of the bike, somewhere away from the negative battery cable. That should be within  a few tenths of a volt of the measurement across the battery post. It is beginning to sound like the negative battery cable is bad or the contact point to the frame maybe the connection of high resistance. Did you measure the battery voltage using the same ground that you used measuring the two light sockets? The electrons leaving the battery must have a path back to the other post. I'm told that the direction of electron travel is out of the negative post through the circuit and back to the positive post. What matters isn't the direction but the path must be complete before the electrons can do their job.

It is beginning to sound like the negative battery cable is bad or the contact point to the frame maybe the connection of high resistance.

Wouldn't this affect other things as well?



Chris

[FJFAST]

It is beginning to sound like the negative battery cable is bad or the contact point to the frame maybe the connection of high resistance.

Wouldn't this affect other areas as well?

Greg

[ct7088]

Yes a bad battery ground cable would stop the starter from working at the very least also almost every circuit on the bike could be affected. Are there any items other than the high beam indicator that stop working when the relay harness and headlamp sockets are connected? Where did you connect the red and black wires that are part of the EB harness?

[FJFAST]

No other circuits appear to be affected. EB harness is connected red to positive and black to negative. I double checked left switch power and have @5.5v going in and 5.5v coming out on yellow and green.

Greg

[Pat Conlon]

Ok, now go backwards. Find the spot in the harness (or the connector) where the voltage goes from your battery voltage, 12volts, down to 5.5v.