computer module

[barend]

Sam Almgren came over from Ga today to try and help me fix my dim highbeam. Thanks Sam!!. Alas we (he) had no luck! Actually Sam seems to think the computer module has a problem since I don't have 12 V going to the high beam. Anyone have one of them dar puppies laying around? In the absence of that, a Mk1 dash with 30K miles?

After that, anyone interested in disecting the old one or trying to fix it (Dingy?)?

[dingy]

Here is a link to re-soldering the connections in the CMU.

 

I just did a similar repair to my CLASS system controller and that fixed it.

 

I have a spare unit out of my 83 head I could lend you if you aren't comfy doing this.

 

I had a problem with the head lights also on bike before its rebirthing this winter. My solution was to bypass the CMU at that point in time. I added a relay connected to the dimmer switch that directly switched hi-lo beam. I seemed to remember thinking the problem was in the reserve lighting unit. So I am not a 100% sure my CMU would correct your problem.

 

I could re-solder terminals on yours. I would have no way of testing it though. I put an 88 wiring harness and instrument cluster in mine and they have completely different wiring hookups.

 

I have a couple of spare reserve lighting units also.

 

PM me.

 

Gary

[bkuhr]

Would suggest before pulling dash to get cmu out, first back-stab pins on connector for high beam input, and high beam output. If no input have different problem. If have input, but no output, CMU problem. If have input and output likely wiring problem to the light.

 

If looking at 83 diagram correctly, Hi input=Yellow/red and HI output= Yellow/green and the CMU connector

[dingy]

This is a way to isolate whether problem is in CMU or reserve lighting unit.

 

I just tried this on mine and it works.

 

Disconnect the reserve lighting unit from wiring harness.

 

It's an 8 pin connector going into a black rubber covered rectangular box. About 4" long, 2" wide and little over an 1" thick.

 

Looking at the male end of connector, the one attached to wiring harness, there is a Blue wire with a White tracer on it. If you temporarily attach a jumper from positive battery to this wire, the head light should work if the problem is in reserve unit or the feed wire coming out of fuse for headlight.

If it acts the same, then problem is in CMU.

 

Also check that headlight fuse clips are not weak. Pull on headlight fuse and see if there is good contact to fuse. This is a common problem with the fuse blocks on these bikes. The metal clips to the fuse gets weak and doesn't make good contact.

 

Another place could be in the start switch. The circuit for head light runs through start button, so head light goes out when bike is cranking.

 

Here is link to the schematics for these bikes.

 

http://www.venturerider.org/forum/sh...ad.php?t=42384

 

Gary

Edited April 19, 2010 by dingy
Edited problem location line.

[barend]

Would suggest before pulling dash to get cmu out, first back-stab pins on connector for high beam input, and high beam output. If no input have different problem. If have input, but no output, CMU problem. If have input and output likely wiring problem to the light.

 

If looking at 83 diagram correctly, Hi input=Yellow/red and HI output= Yellow/green and the CMU connector

I want to say output was like 3V, maybe Sam will confirm that since he's the one traced that out.

 

This is a way to isolate whether problem is in CMU or reserve lighting unit. Disconnect the reserve lighting unit from wiring harness.

It's an 8 pin connector going into a black rubber covered rectangular box. About 4" long, 2" wide and little over an 1" thick.

Looking at the male end of connector, the one attached to wiring harness, there is a Blue wire with a White tracer on it. If you temporarily attach a jumper from positive battery to this wire, the head light should work if the problem is in reserve unit or the feed wire coming out of fuse for headlight.

If it acts the same, then problem is in CMU.

Also check that headlight fuse clips are not weak. Pull on headlight fuse and see if there is good contact to fuse. This is a common problem with the fuse blocks on these bikes. The metal clips to the fuse gets weak and doesn't make good contact.

Another place could be in the start switch. The circuit for head light runs through start button, so head light goes out when bike is cranking.

Gary

You mean I have to take it all apart again?? I'll do some digging and see if I can find that reserve unit thingy and try that. Would it be too presumptuous to think that it is under/behind the headlight?? I do want/need to replace the fuse block at some point but the fuses do appear to be snug in there. I'll have to double check.

[Condor]

Sam Almgren came over from Ga today to try and help me fix my dim highbeam. Thanks Sam!!. Alas we (he) had no luck! Actually Sam seems to think the computer module has a problem since I don't have 12 V going to the high beam. Anyone have one of them dar puppies laying around? In the absence of that, a Mk1 dash with 30K miles?

After that, anyone interested in disecting the old one or trying to fix it (Dingy?)?

 

I don't think the high beam circuit goes thru the CMU. If you had a dim low beam, and the high beam worked, it would be the CMU. I'd check switches, conections, and the bulb. Sometimes a new bulb can be bad.

[Venturous Randy]

I don't think the high beam circuit goes thru the CMU. If you had a dim low beam, and the high beam worked, it would be the CMU. I'd check switches, conections, and the bulb. Sometimes a new bulb can be bad.

 

You may be right condor, but I believe I have fixed both the hi and low beam thru the CMS. I have fixed several of the CMS's over the years, but my memory is a lot older than my bike.

RandyA

[Condor]

You may be right condor, but I believe I have fixed both the hi and low beam thru the CMS. I have fixed several of the CMS's over the years, but my memory is a lot older than my bike.

RandyA

 

I think what happens is the high beam is a direct connect for safety reasons?? So you will always have something no matter what. Even if the CMU goes bad. Maybe what happens is the CMU, when it detects a bad low beam, will light up that blue or white square light on the dash. I had the dim low... geeze sounds like a chinese dish.... on the '83 when I first bought'er. I just adjusted the beam down and used it that way. Then I found a mint '83 dash on Ebay and swapped them out. Problem gone....

[dingy]

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

Edited April 19, 2010 by dingy
edited last paragraph

[Condor]

OK, Got it. If the head light down't work properly it's either a bad bulb or the CMU... I gotta headache.... Dingy, Where do you find time to write all these long disertations on Venture systems and still work on your project??? OK, I bet you don't sleep....