Dim Headlight

[Dr. Psycho]

My headlight has lost it's brightness. At first it was only on the dim side now both high and low beams are not working correctly. THe headlight indicator on the dash is lit also. When this first started happening I could reach in and move the wires behind the headlight and it would work now nothing.

 

I can not see any broken or frayed wires. THere are many things I can do but electrical is not high on that list. Any help would be greatly appreciated.

Thanks

[Trader]

sounds like either a bad connection...or a bad ground?

 

First thing I would try is to undo the connections at the plugs, spray with contact cleaner spray, plug and unplug a few times...then put a LITTLE dieletric grease on the plugs, reconnect and try it out..

 

If that doesn't help then hopefully someone else will have some ideas.

Would a dirty hi/low switch affect it like that?

[dingy]

http://www.venturerider.org/forum/showthread.php?t=58880

 

The head light indicator on the dash is triggered by a current sensing circuit on the CMU (dash indicators) circuit board. The current for the bulbs passes throug a coil of wire that triggers a reed switch if there is current within design specs.

 

Considering you are able to wiggle wires and affect the symptoms, it would seem that problem is in vicinity of head light. Other area that would be suspect is the start switch.

 

The three primary connectors I would check are the one going into head light socket (dudh). 2nd is the one going into the Reserve Lighting unit. This is a black rubber covered unit about 4" x 2" x 1" (roughly). Has about an 8 conductor connector going into it. I think it sets at the very top front of the head light pocket. 3rd would be the connector going into the CMU on the cluster head.

 

Also involved as far as connectors go is the 6 conductor one that goes to the left handlebar controls & another 6 conductor one that goes to the right handlebar controls.

 

Check all of these connectors and see if wires are corroded or dirt is in connector.

 

Wiring diagrams are located at links below.

 

This one is complete wiring schematic for 83 Venture, it shows all the connectors in place. This one is best to use for tracing wires out as how they are routed to various places on the bike.

 

http://www.venturerider.org/wiring/83%20Yamaha%20Venture%20TK%20Wiring%20Diagram%20Rev%20C.pdf

 

This one is simplified wiring schematic for 83 Venture, it shows same circuits as above schematic, but without the connectors, which simplifies the layout of the wiring and is easier to look at how circuits function.

http://www.venturerider.org/wiring/83%20Yamaha%20Venture%20TK%20Simplified%20Circuit%20Diagram%20Rev%20C.pdf

 

Gary

[bkuhr]

My headlight has lost it's brightness. At first it was only on the dim side now both high and low beams are not working correctly. THe headlight indicator on the dash is lit also. When this first started happening I could reach in and move the wires behind the headlight and it would work now nothing.

 

I can not see any broken or frayed wires. THere are many things I can do but electrical is not high on that list. Any help would be greatly appreciated.

Thanks

 

You did not state what bike this problem this is on, but I assume it is your '83 listed in your profile. Thw 'white' headlight indicator is an indication that the RLU(reserve lighting unit)has detected a problem and is trying to switch to the other light beam from which you have selected.

 

Power for the system first runs from the headlight fuse to the released contacts of the push button starter switch (so the headlight turns off during starting), corrosion here is possible, but usually the contacts fail to make connection and headlight does not work at all.

 

Next power goes to the RLU. The RLU monitors the power output to the dimmer switch(later) and the power output from the CMU(later) and if it detects a failure, it switchs power to the other headlight beam. Not very often, but a failure of the RLU can cause you symptoms. It could be removed and bypassed for testing, but is difficult to get to behind the right hand fairing.

 

After the RLU the power goes to the High/Low dimmer switch.

 

From the dimmer switch, either the high, or the low, as selected, power is sent the to CMU (computer monitoring unit dash display). Internal this unit are heavy coils that the power is run thru and back out to the actual headlight filiments. The purpose of the coils are to serve as an electromagnetic to active a reed switch internal of the coil. This creates a 'current' sensing failure detecting system. There are actually 4 of the sensing sytems internal the CMU. They are for 1-Headlight High, 2- Headlight Low, 3- Tail running light, 4- Tail brake light. The high current running thru these coils are known to melt the soldier connections on the pc board internal the CMU, but are usually repairable.

This problem internal the CMU is your most likely issue. I would suspect that first high, and now both high and low coils have gone open, and the RLU is doing as designed and is opetating both beams at lower power. There are numerious posts on repair/ or bypass of the CMU, but all will involve removal of the dash.

 

The last possible problem could be a corroded connector directly at the headlight.

 

I think I would pull the windshield and dash cover and touch a bypass wire from cmu in to cmu out for each high and low beam from the rear connector(backstab) of the CMU. If beams came back full brightness then you could be sure you would need to repair the CMU, and now the dash is nearly out.