Ducati ST2 blinkers and brake light not working

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Shorts · #1 Unread post by **Shorts** » Tue Apr 03, 2007 10:40 am

All functions in the left bar work except for the blinkers. No blinkers front or rear. My front brake light switch is also not working. I have found the Radio Shack part number for the switch, but I'll see if there's an available alternative here.

High_Side, I could use your help on this one. Here's what I have so far:

Well, I have some results from testing. When testing the brake light switch for resistance, I could not get the reader to zero out when ON (brake engaged). When OFF (brake disengaged) the reading was the intial "off the scale" reading.

As for the turn switch, there was continuity in the handlebar switch in both directions, that is good.

Then I jumped up the power line to testing the fuse connection (#04 in wiring diagram), it too was ok (fuse intact, voltage reading 12.5). That tells me the ground is good and power is available to the Indicator Flasher (#05) which is next inline from that particular fuse.

At the Indicator Flasher (#05), I could test that relay individually because I cannot find it And I have an idea where it is, and I surely cannot get to it without removing that middle fairing. So to try to test that connection I went from #04 Fuse block -->through #05 --> to the #38 harness connection that feeds the left switch housing blinker. I got voltage of 12.5 and a resistance reading at 10.5. Out of curiosity (an no electrical knowledge whatsoever) I tested the connection from the left side of the fuse connection to the same output there at #38, voltage was 0.0 and resistance 6.75.

Can anyone help me decifer this chicken scratch numbers I've put together? From my extremely limited electrical system knowledge, I'm thinking the #38 Indicator Relay is the problem. It was my first thought prior to testing, but unless you test, you don't really know for sure.

What do you guys think? Is there something I should have done differently? I'd like to reiterate that all other functions on the left switch housing are properly working, as also on the right housing (with exception of the brake light switch).

Are the blinkers like a string of christmas light in that if one goes, all of them go?

Shorts · #2 Unread post by **Shorts** » Thu Apr 05, 2007 12:40 pm

Well Shorts, I'd go with my gut and just replace the blinker relay and the brake light switch. First though, apply some power to the blinker leads in the harness to be sure they work if they get juice.

#3 Unread post by **Sev** » Thu Apr 05, 2007 2:09 pm

I might be wrong here, but doesn't the voltmeter measure a voltage drop across a location? So if your fuse is showing 12.5V that means it has no continuity... there's a 2.5 volt difference between one side and the other.

Test the fuse itself for continuity.

Shorts · #4 Unread post by **Shorts** » Thu Apr 05, 2007 2:18 pm

Sev wrote:I might be wrong here, but doesn't the voltmeter measure a voltage drop across a location? So if your fuse is showing 12.5V that means it has no continuity... there's a 2.5 volt difference between one side and the other.

Test the fuse itself for continuity.

Shorts · #5 Unread post by **Shorts** » Thu Apr 05, 2007 8:03 pm

The fuse is good. The voltage reading is the voltage through, not a voltage drop.

I need to figure out how to put juice on the blinker leads there on the harness to make sure the bulbs are making ontact with its tabs. There is a clear connection audible with the sound test from harness to blinker socket.

#6 Unread post by **Sev** » Fri Apr 06, 2007 3:53 am

Do you have a copy of your wiring diagram that you can post?

From memory the quickest way to find the problem is to identify the entire circuit and start testing for voltage drops across specific sections.

EG.
voltage drop across the switch should be in the range of .1 to .5 volts.
from the battery to the switch should be about .1 to .2 volts

Should basically go like this:

battery - wire - fuse - switch - blinker relay - turn light - turn light - indicator light - battery

The two turnlights should be connected in parallel. The indicator/blinker relay works in that it senses the voltage drop as the lights activate and breaks the circuit when the voltage changes. If one of the lights burn out the voltage difference changes and the lights blink at an increased rate (this is a warning for you to change the burnt out light).

So basically you're looking for a break in the system.

Test for continuity between:

battery and fuse
across the fuse
fuse and switch
across the switch
switch and relay
across the relay

(I think it's unlikely that the problem will be in this section based on the problems you're talking about)
relay and each turn signal separately
across each turn signal

Finally from the turn signals to the battery (should not be this either)

I hope that helps

Shorts · #7 Unread post by **Shorts** » Fri Apr 06, 2007 11:55 am

Sev, I do have a diagram, let me get it separated from the pdf.

Bah! Can't get the diagram to come out decent and photobucket likes to resize my work. PM me your email addy and I'll fwd the single page pdf of the diagram.

#8 Unread post by **Sev** » Fri Apr 06, 2007 12:21 pm

prt scrn

paste into photoshop, or paint or something, and save.

Shorts · #9 Unread post by **Shorts** » Fri Apr 06, 2007 12:46 pm

...

PM your email addy, I'll fwd the single page pdf so you can actually see the details

#s 4, 5 and 40 are the key players

#10 Unread post by **Sev** » Fri Apr 06, 2007 1:09 pm

Sweet Mary and Joseph. You win.