Tail light issue, 96 RT 1100

[Woodchips]

On a ride late yesterday, my fellow rider saw that the rear tail light was out, we confirmed the brake light  and the signal lights were working fine. Today I pulled the tail light assembly to replace the bulb but discovered the bulb was fine. I double checked with another working bulb but no change.

It appears that there is no power to the socket and a check of all fuses indicates they are good.

Any suggestions as to where I might look next?

 

[dirtrider]

33 minutes ago, Woodchips said:

On a ride late yesterday, my fellow rider saw that the rear tail light was out, we confirmed the brake light  and the signal lights were working fine. Today I pulled the tail light assembly to replace the bulb but discovered the bulb was fine. I double checked with another working bulb but no change.

It appears that there is no power to the socket and a check of all fuses indicates they are good.

Any suggestions as to where I might look next?

 

 

Evening  Woodchips

 

Start by checking fuse #1 in the underseat fuse box.

 

If OK there (12v on BOTH sides of the #1 fuse with key-on)   then use a voltmeter or 12v test light & check for 12v into & out of both brake switches with pedal or lever applied.

 

If switches function OK then possibly a  broken wire running to rear of bike, or problem in the rear light pigtail connector.

[Woodchips]

Evening DR

 I pulled all the fuses and did a continuity test on each one, but will test them as you suggest with a volt meter. I’m not sure I follow how the two brake switches are involved as both activate the brake light bulb.

From the left side of the bike, which fuse is Number 1?

 

Ron

[dirtrider]

8 hours ago, Woodchips said:

Evening DR

 I pulled all the fuses and did a continuity test on each one, but will test them as you suggest with a volt meter. I’m not sure I follow how the two brake switches are involved as both activate the brake light bulb.

From the left side of the bike, which fuse is Number 1?

 

Ron

 

 

Morning Ron

 

 

The #1 fuse is the 1st one in from the shifter side of motorcycle.

 

On the brake switches, those are (N/O)  & go closed when the pedal or lever is used. The switches are in parallel so you can treat either switch as  the only one. 

 

12v from ign switch (key-on)  runs to fuse #1, then from fuse #1 (12v)  runs to 'both' front & rear brake switch's, then (12v) from (switch being used) runs to the brake light bulb.  

 

So (with key on) check fuse #1 for 12v out, then   check both switches for 12v in, then activate each switch & check for 12v out of switch being used, then hold brake lever in (use zip tie) or hold brake pedal down & check for 12v on brake light (grey/yellow) wire at rear light socket.

 

If tail light is working then rear bulb  ground side is usually OK but that isn't 100% conclusive.

[Woodchips]

Good evening DR

I was away from the garage for a few days but will follow your suggestions tomorrow and report back.

As always thanks for support.

Ron

[Woodchips]

Evening DR

After just over an hour today following your advice on tracing down the no tail light issue with no results, I pulled the fuse and replaced it, the bulb came on. Grrr…. the first thing I checked last week was that fuse by pulling it and checking the continuity, 0.00 on the volt meter so put it back in and no tail light. Embarrassing to say the least.

Thanks again

Ron

 

[dirtrider]

8 hours ago, Woodchips said:

Evening DR

After just over an hour today following your advice on tracing down the no tail light issue with no results, I pulled the fuse and replaced it, the bulb came on. Grrr…. the first thing I checked last week was that fuse by pulling it and checking the continuity, 0.00 on the volt meter so put it back in and no tail light. Embarrassing to say the least.

Thanks again

Ron

 

 

 

Morning Ron

 

Glad that you found the problem.

 

I presume that you mean 0.00 on your 'ohmmeter' as removed fuse + voltmeter cannot test a fuse for continuity as there is no voltage source to test the continuity. 

 

A quick pre-test to see if your meter will read an open (blown) fuse is to simply hold the probe metal tips together. If you don't see a significant  reading difference with probes together or apart then it won't test a removed fuse.

[Woodchips]

I have been testing probes like that for many years, it’s still a mystery but problem solved. 

[MontanaMark]

Woodchips,

 

I've not seen a 'tested' fuse not work, but I have seen visually inspected fuses that appear 'good' fail.  Happened recently to a friends Moto Guzzi.  Headlight wasn't working so we checked all the fuses visually.  All appeared ok.  After a ride/tow and $500.00 later, the shop found that the headlight fuse was bad.

 

Cheers,

Mark

[BF204]

 Any chance you just forgot to switch your multimeter from V to Ohms when testing continuity?  FYI, my multimeter was acting weird not long ago, so I gave it its first new battery in years, and it went back to functioning normally...

[Woodchips]

At my age, anything to do with forgetfulness is possible 😂. 

A new fuse and all is well again👍