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08 Norge Taillight Issues

WindwardWarrior

WindwardWarrior

Tuned and Synch'ed
GT Famiglia
Joined
Sep 25, 2011
Messages
94
Location
Kelowna
Good day everyone and Happy New Year!

I've seen some great posts and replies to the Electrical Issues on some Guzzi's. I loved the quotes I saw that said 'Moto Guzzi, making electricians from riders for 90 years'!

Well, I am not an electrician and my post will likely show my ineptitude.

I have Carl Allisions' 07 Norge Wiring Diagram which is helpful.
The battery voltage is >12,75 V and fully charged. It is 2 seasons old, well cleaned terminals etc.

I noticed that theTail Light was not functioning in the middle of 750 KM Trip. The Brake light functioned, and I was only riding in the daylight so I was not too concerned.

I made it home and then found that the Low Beam Headlamps stopped functioning. I got the wiring diagram, tested, traced wires and found that one of the harnesses from the LH Headlamp Controls may have been disconnected. I changed the ECU last winter (reflashed unit), so possibly I had jarred one of the connections? Additionally I changed Headlamp Low Beam Relay and the Headlamp issue was rectified with the relay replacement.

With the tail light, I tested the circuits w/o Engine Running and found that the voltage seemed to be as specified in some other posts. I assumed that the LEDs for the Tail Lights were the culprit. After receiving a new Tail Light this is not the problem.

The voltages I have are:

Key On=Engine Off
Tail Light (Yellow) 12.11V
Brake Off (Blue) 7.2V
Brake On (All) 12.0

Should there be 12V at all of the wires when applying the brakes? One of them (yellow green) shows a nominal resistance when connected to ground.

Engine On
Tail Light 13V
Brake Off Blue voltage erratic and reading higher than Battery Voltage
Brake On 13V Yellow and Yellow Green

Is there a specific testing sequence that I should follow? Which of the wires is actually ground?
Which wires should have the variable voltage? What influences the voltage to be reduced?

Thanks in advance for checking out my post!

Mark
 
First check the ground connection for the tail light. There should be continuity to ground at all times. Also there shouldn't be any voltage on the brake light line with the brakes not activated. Disconnect both brake light switches, I bet the tail light will come on. Then re-connect the brake light switches one at a time. When the tail light goes out, that is the defective brake light switch. My guess is a brake light switch is allowing voltage through and blocking tail light function.
 
Hi John.

Thanks. I'm traveling for work until Friday. I will try your recommendation when I get back. Cheers.
 
Do you have any additional lights added to the circuit? When I installed a lighted Givi trunk on my Norge the tailight quit working. It was due to the incandescent bulbs wired into the same circuit as the LEDs. I added a diode in the circuit and all was better.
 
Abbienormal, thanks. No, I haven't got any additional lights at this point. I'm thinking if adding LED lights to the Top Box, but only after the tail light issue is rectified! Cheers..
 
I added a high level stop light to the top box on my Norge, using LEDs and had no problems.

Where are you testing the voltage?
Have you done the start relay rewire mod? If so check fuse B.
Are the front position lights coming on when you turn on the ignition?

I can't see how, looking at the diagram, you can get anything but 12 volts on the supply to the tail light, it's the same bit of wire that feeds the front bulbs and they need 12v and anyway, the feed comes direct from the ignition switch.
 
Last edited:
Brian UK said:
I added a high level stop light to the top box on my Norge, using LEDs and had no problems.

Where are you testing the voltage?
Have you done the start relay rewire mod? If so check fuse B.
Are the front position lights coming on when you turn on the ignition?

I can't see how, looking at the diagram, you can get anything but 12 volts on the supply to the tail light, it's the same bit of wire that feeds the front bulbs and they need 12v and anyway, the feed comes direct from the ignition switch.
Click to expand...

Thanks Brian. Yes, I made the starter relay mod. I have current to the tail lamp (tested at connection). I will post a reply after I get back home to apply a few of the recommendations. Cheers
 
Hi Brian. Back home. Yes, I have all lights except taillight. I followed John's suggestion disconnecting the brake lamp switches. There was still no taillight. I checked fuse B (all fuses) and all good.

The voltage seems as required. There is continuity to ground through the blue wire .


Thoughts?
 
Last edited:
I thought the low voltage on the brake line you posted in your first post was interfering with the operation of the tail LEDs. Was that voltage still present with the switches disconnected? If so that would be something to investigate.

If you disconnect the light and run test leads/jumpers from light ground to ground, and from tail to 12V does the light illuminate? Try this with both units you have and let us know the results. This takes the bike wiring out of the equation and will tell if the LEDs are working correctly.
 
Hi John:
Thanks for following up! The voltage in the original post for the brake line is incorrect as you will see below.
Well, I was on the same path as you with disconnecting the light and running jumper leads.

These are the results! I used both lights to confirm.

Key On, Engine Off, Brake switches connected
Blue Wire has continuity to ground. I also verified this with a 12V Bulb which illuminated when connected to + terminal
Yellow (Tail Light) has 12V
Y/G has .832DCV
Y/G disconnected (Brake) Taillight Illuminated
Y/G Connected Tail Light goes out
Brakes actuated Brake Light comes on

The voltage results are the same with the Brake Switches disconnected.

Thanks John....
 
It has been a few years since I played with the lights on my Norge but I was just looking at this thread again and thought of something. Do not the same LEDs that light up for the tailight also light up as the brake light? I am thinking those that are used for both purposes run at a lower voltage when running lights then go to full voltage for the brakes thus becoming brighter.
That was a while ago but I seem to think that is what I found.
 
Just to confirm. When you disconnect the wire for the brake light, the tail light will illuminate. Is this correct? Is the intensity the same as when the brake is applied or not?
 
See if you get the same voltages with the brake light switches dis-connected. If so, you are getting a voltage leak from the harness. 0.832 VDC is pretty low, but it may be just enough to prevent proper operation. Trace the brake light wire back until you get 0 VDC, the problem will be between there and the tail light.
 
First of all, the Blue wire is the earth, so you should not have any volts there at all.
The tail light wire is Yellow, and the brake light feed is largely Green.
You should see 12v on the yellow wire if the ignition is on. You will also see 12v on the green wire if the brake is on. If you have volts on the Blue earth wire then you have an earth fault somewhere.

Yes the same LEDs are used for both lights, but the lower voltage for the tail light is supplied by components inside the light unit. The supply to the light is 12v.

I'm taking this information from my own experience and Carl's wiring diagram.
http://www.thisoldtractor.com/guzzi007/schematics/2007_Norge_ABS.gif
 
OK, just been out and measured the voltages on my Norge.
I can confirm the Blue wire is earth.
The Yellow/Grey wire is the tail light, and has 12v on it when the ignition is on.
The Yellow/Green wire is the stop light and has 12v on it when the brake is applied.

So, if you have volts on the blue wire measured to battery negative, then you have a high resistance joint in the earth return. This would probably allow the stop light to illuminate, but not as brightly as it should, but the tail light would not illuminate.
 
Brian,

What is the voltage on your yellow green when the brake is not applied? If 0 VDC, you may be on to something with Windwarrior's bike. The low voltage he is observing may be due to a poor ground and it is a bleed from the tail light circuit.

Windwarrior, if you can, add an addition wire from a known good ground to your blue (ground) wire. If the light function correctly, than a poor ground is the issue.

I've seen poor grounds cause a problem with bulb type tail lights. Tail would work, then when brake is applied the light goes out as 12 volts is present on both filaments.
 
Hi Brian and John:

Thanks for your insights! Well, as always we should look at we did last as the cause of what might be the problem today.....

In the winter of 2014 I installed a Motor Cycle Cruise Control from the Motor Cycle Cruise Controls Company in Australia. I used it throughout the summer without issue. I suspected this might be the issue, but.....

Following Johns suggestion, I traced the Y/G Wire back to the connector that joins the brake light connector on the bike to the brake power sensor wire on the cruise control unit wiring harness. At the Grey Wire (connects to Y/G on the bike) there was .915VDC.

I removed the MC Cruise connector, reconnected the brake wires as per Guzzi and voila, all is good in the garage. Now to put it all back together!

So the brake light issues is resolved! Now if there is a fix for the Cruise Control Unit I will be cruising in comfort again.

Have the best day gentlemen and thank you for your insights!
 
Install a diode on the cruise control brake sensor wire. That will allow current to flow in only one direction. As to value I'm not sure. Hopefully someone on the forum has a suggestion.
 
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