robclark63 Posted September 22, 2012 Share #1 Posted September 22, 2012 I am working on an 88 venture and have a fault on the display...it is when the headlight on low beam....I soldered all the connections in the CMS...but when the low beam light is on the warning light is on and the display shows the headlight...any information would be great...Thanks in advance. Link to comment Share on other sites More sharing options...
Flyinfool Posted September 22, 2012 Share #2 Posted September 22, 2012 Shine the headlight on the wall. Are you really getting both hi and low beam? Not just is the headlight on. On a 1st gen if either the hi or low element burns out it will automatically switch to the other one so that the world does not go dark. The bike can not tell the difference between a burnt out bulb and a bad wire or connection. Link to comment Share on other sites More sharing options...
dingy Posted September 22, 2012 Share #3 Posted September 22, 2012 Below is a sequence of operation with the reserve lighting unit. This is a post I did 2 years ago relating to RLU operation This is what I have found with the operation of a working system on an 1988 wiring setup. I have just verified this information on my bike. I have independent spade lug terminals hooking up to the headlight plug in the wiring harness,due to my projector headlights, so it is easy to simulate burnt out bulb conditions. The reserve lighting unit is located on the right side of the headlight unit. When the dimmer switch is set to LOW and low beam lamp is not functioning, the reserve unit illuminates the high beam lamp at a reduced voltage, this keeps from blinding oncoming traffic. The dash white indicator light "Headlamp" is illuminated. CMU Headlight icon is displayed. When the dimmer switch is set to LOW and High beam lamp is not functioning. The dash white indicator light "Headlamp" is not illuminated. CMU Headlight icon is displayed. When the dimmer switch is set to HIGH and High beam lamp is not functioning, the reserve unit illuminates the low beam lamp at a near normal voltage. The dash white indicator light "Headlamp" is illuminated. CMU Headlight icon is displayed. The "High beam" indicator is lit. When the dimmer switch is set to HIGH and Low beam lamp is not functioning. The dash white indicator light "Headlamp" is not illuminated. CMU Headlight icon is displayed. The "High beam" indicator is lit. When both lights are not functioning, only the CMU icon is displayed when Low beam is selected. When HIGH beam is selected, the dash white indicator light "Headlamp" is illuminated. CMU Headlight icon is displayed. And the "High beam" indicator is lit. Assuming the wiring diagrams are correct, the high and low beam run through the CMU. There is an input circuit and an output circuit for both the high and low beams. The reserve lighting unit is where the input wire from the headlight fuse goes first. I am guessing that the current on this wire is used to determine if the lamps are lit or not. Last paragraphs are based on this assumption. If the Low beam is selected at the dimmer switch, a positive voltage is sent to the CMU, which then passes that voltage back to the headlamp. If headlamp is burning, reserve lighting unit does nothing. It senses normal current on feed wire, and it is getting voltage on its low side input. If the High beam is selected at the dimmer switch, a positive voltage is sent to the CMU, which then passes that voltage back to the headlamp. If headlamp is NOT burning, reserve lighting unit senses very low current on feed wire (some current consumed in CMU), and it is getting voltage on its low side input. The reserve lighting unit then outputs reduced positive voltage on the High beam circuit, thus illuminating High beam and signaling CMU that low beam filimant is burnt out. If the High beam is selected at the dimmer switch, a positive voltage is sent to the CMU, which then passes that voltage back to the headlamp. If headlamp is lit, reserve lighting unit lights the High beam indicator lamp. It senses normal current on feed wire, and it is getting voltage on its high side input. If it is not lit, the reserve lighting unit outputs positive voltage on the low beam circuit, thus illuminating low beam and signaling CMU that high beam filament is burnt out. Gary Link to comment Share on other sites More sharing options...
robclark63 Posted September 23, 2012 Author Share #4 Posted September 23, 2012 Thanks Gary that is a nice write up!! I am used to working on old acvw's with out many electronics...especially not a small computer system so I am learning as I go which is fun:) Thanks again for the write up!! Link to comment Share on other sites More sharing options...
robclark63 Posted September 23, 2012 Author Share #5 Posted September 23, 2012 went out and checked voltage coming from red/yellow and red green wires to headlight...on low beam both wires give 12 volts on high beam one gives 12 and the other gives4.3-4.5??? I would think that high beam would give more volts instead of low...Is there a proper headlight for the bike?? I will have to look in my manual...thanks for information on the voltage if you have any...thanks again... Link to comment Share on other sites More sharing options...
dingy Posted September 23, 2012 Share #6 Posted September 23, 2012 went out and checked voltage coming from red/yellow and red green wires to headlight...on low beam both wires give 12 volts on high beam one gives 12 and the other gives4.3-4.5??? I would think that high beam would give more volts instead of low...Is there a proper headlight for the bike?? I will have to look in my manual...thanks for information on the voltage if you have any...thanks again... Attached is a picture of the headlight wiring on an 88. These schematics are located at link below. http://www.venturerider.org/forum/showthread.php?t=42384 Only red/Yellow wire I see is the one going to the high beam indicator light. The wires for the bulb elements are Green/Red (low) & Yellow/Green (high). The first color in wire designation is the main color of the wire, second color is the tracer color. The voltage on the wire, which should only be one or the other, read to ground (depending on dimmer switch) should be the same. The bulb filaments are different which accounts for the lighting level difference. The Reserve lighting Unit (RLU) may have failed. Another possibility is dimmer switch needs cleaning, though I do not recall this being a problem. Cleaning dimmer switch link below. http://www.venturerider.org/forum/showthread.php?t=42721 I have seen an connector to the headlight bulb that was melted due to dirty contacts. Similar to the regulator plug melting issues. Gary Link to comment Share on other sites More sharing options...
robclark63 Posted September 23, 2012 Author Share #7 Posted September 23, 2012 You are correct that is the color of the wire...I went out and bought a new bulb just to make sure that was not it and as I suspected it was not...Low beam is just throwing the fault...I am going to try to clean up the dimmer switch and see if that works and if that is not it I guess it would be that pesky RLU...lol...old things are sometimes fickle:) Link to comment Share on other sites More sharing options...
robclark63 Posted September 23, 2012 Author Share #8 Posted September 23, 2012 I forgot to mention that the light does switch from high to low beam...so I guess the switch is working properly...and I do have 12 volts coming out of the RLU on the blue and white wire (I think that is what wire the Yamaha manual told me to check) and that is what the manual said to have... Link to comment Share on other sites More sharing options...
robclark63 Posted October 3, 2012 Author Share #9 Posted October 3, 2012 After playing around with this fault I dont know what else to do...I guess I will never be able to switch beams...stumped... Link to comment Share on other sites More sharing options...
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