'04 Brutale - testing diode at starter relay? - MVAgusta.net
 2Likes
  • 1 Post By esq'z me
  • 1 Post By esq'z me
 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old 07-15-2019, 02:41 AM Thread Starter
Established Member
 
chandler325i's Avatar
 
Join Date: Jul 2014
Location: Lost Angeles, CA, USA
Posts: 191
Question '04 Brutale - testing diode at starter relay?

Suddenly got the battery voltage light while riding. Blew the 40A fuse, melted things pretty badly. Not sure what caused it yet. I haven't done anything with the battery in quite some time and have been riding regularly. Anyway, I wanted to make sure everything around the relay is ok before I start trying to chase what else could be the issue.

Can the diode be tested in place? I get about a 0.55V reading doing a forward diode test. Testing the diode in reverse, I expected an OL reading, but I got 2.77V.

Is it because it's still connected to the other wiring that could be giving an unexpected reading when testing the diode in reverse, or is that evidence that the diode is shot?

chris chandler
2004 Brutale S
chandler325i is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 07-15-2019, 07:48 AM
Senior Member
 
silentservice703's Avatar
 
Join Date: Feb 2008
Location: Duxbury, MA, USA
Posts: 21,014
Send a message via Skype™ to silentservice703
It is probably because you are testing it in situ.

I would take the solenoid out of the bike and clean all of the connections and inspect the wiring. This is a known weak spot in all MVs. The wiring is probably brittle and failed to ground at some point. Also, the spade connector female side terminals probably could use some “snugging up” to reduce resistance at those connectors.

Using advanced search will reveal many “solenoid” threads.

Gapalicious 2019 at
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
from OCTOBER 2-6, 2019

Call (423) 519-2000 or (423) 253-6213 to reserve your Riverfront Cabin. PM me for The Crow's Nest reservation!!!

Email/Paypal:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


My personal Cell Phone: (781) 223-3020


'07 F4 312R, '10 B4 1090RR, '15 B3 800RR
'07 Ducati Monster S4Rs, '07 Ducati Monster 695
2010 Harley Davidson Ultra-Classic Electra-glide CVO FLHTCUSEBLK
'63 Honda C100A Cub
'61 MVA TRA 125
silentservice703 is offline  
The Following User Says Thank You to silentservice703 For This Useful Post:
post #3 of 10 (permalink) Old 07-15-2019, 01:22 PM
Senior Member
 
theknurl's Avatar
 
Join Date: Jul 2009
Location: Palos Verdes Est, SoCal, USA
Posts: 13,983
Send a message via Skype™ to theknurl
Thumbs up ?

Check between the battery positive terminal and the battery terminal on the solenoid. Then I'd disconnect the battery positive cable and go looking for the short
Connect an Ohm meter to the positive wire and ground, turn the key on, hopefully you'll see continuity
Pull the fuses one at a time
Good Luck

Noel-theknurl

The Forum Curmudgeon
I'm not PC either
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

'08 910R
'05 F4
ph. 310-414-7247 PST, GMT -8
PayPal;
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Skype; theknurl
theknurl is online now  
The Following User Says Thank You to theknurl For This Useful Post:
Sponsored Links
Advertisement
 
post #4 of 10 (permalink) Old 07-15-2019, 06:48 PM Thread Starter
Established Member
 
chandler325i's Avatar
 
Join Date: Jul 2014
Location: Lost Angeles, CA, USA
Posts: 191
Quote:
Originally Posted by theknurl View Post
Check between the battery positive terminal and the battery terminal on the solenoid.
I thought of a theory during my hour train commute -- the positive terminal on my battery is partly exposed. I have a Shorai LFX19A4-BS12 and probably should have gotten a new terminal cover when I installed it since the stock one doesn't cover it all the way. I keep a helmet lock and small cable lock in the tail. It's possible either of those could have shifted down and caused a short. I didn't consider that when I pulled them out of the tail to start looking at things

Right now I'm focused on verifying the integrity of the diode and solenoid to verify whether it was the cause or just a symptom. To do a reverse test on the diode I think I need to disconnect whatever is on the other side of those two wires so that there's no way for the voltage from my multimeter to be doing a "back door" trip through those cables instead of the diode. Too bad the electrical diagrams I have are all so low res it's nearly impossible to see the wiring color labels

One might rightfully ask, "Why not cut the diode out to test it and just solder it back in if it's good?" Because I'm lazy and there's no AC power in my garage. Easy to solder it back in, PITA to figure out how to get power to the garage to run the soldering iron. Also wouldn't be fun to pull the whole harness just to test/repair that diode

chris chandler
2004 Brutale S
chandler325i is offline  
post #5 of 10 (permalink) Old 07-15-2019, 06:51 PM Thread Starter
Established Member
 
chandler325i's Avatar
 
Join Date: Jul 2014
Location: Lost Angeles, CA, USA
Posts: 191
Quote:
Originally Posted by silentservice703 View Post
It is probably because you are testing it in situ.

I would take the solenoid out of the bike and clean all of the connections and inspect the wiring. This is a known weak spot in all MVs. The wiring is probably brittle and failed to ground at some point. Also, the spade connector female side terminals probably could use some “snugging up” to reduce resistance at those connectors.

Using advanced search will reveal many “solenoid” threads.
The solenoid threads are the only reason I had any idea there's a diode in the first place!

Everything looks surprisingly clean. I'm having trouble getting one of the spade connectors out of the terminal because of the way the terminal deformed from the heat. I'm trying to source a replacement white terminal so I can cut the old one off and check the condition of that 4th spade connector

chris chandler
2004 Brutale S
chandler325i is offline  
post #6 of 10 (permalink) Old 07-16-2019, 06:09 AM
Old Wing Nut
 
esq'z me's Avatar
 
Join Date: Aug 2007
Location: Marietta, GA
Posts: 18,282
Send a message via Skype™ to esq'z me
A short between your battery positive terminal and ground will just make big sparks and possibly set your bike on fire...no fuses involved !!!

Your loose and overheated as a result solenoid connector is the probable cause of your fuse blowing.

Replacement connectors are here:

Motorcycle 6.3mm - 250 Connector and Terminals

Here is a recent thread related to that connector:

https://www.mvagusta.net/forum/153-g...ed-melted.html
silentservice703 likes this.

I used to be fast....now I just dream about it.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

'08 910R (Gina), '04 F4 SPR #275 Track Bike (Lola), YSR50 (The Rabbit), '71 CB100 (Lil' Red), '75 RD350C (Orange Bird) restoration project, '70 Suzuki F50 (Baby Blue)
esq'z me is offline  
The Following User Says Thank You to esq'z me For This Useful Post:
post #7 of 10 (permalink) Old 07-16-2019, 09:02 AM
Senior Member
 
ViggenF4's Avatar
 
Join Date: Aug 2018
Location: Eastern Finland
Posts: 326
I noticed that water likes to find its way to the 40amp fuse housing. That and the loose connections will mean trouble.

F4 750 with Brutale 910S motor
ViggenF4 is offline  
The Following User Says Thank You to ViggenF4 For This Useful Post:
post #8 of 10 (permalink) Old 07-16-2019, 08:31 PM Thread Starter
Established Member
 
chandler325i's Avatar
 
Join Date: Jul 2014
Location: Lost Angeles, CA, USA
Posts: 191
Quote:
Originally Posted by esq'z me View Post
A short between your battery positive terminal and ground will just make big sparks and possibly set your bike on fire...no fuses involved !!!

Your loose and overheated as a result solenoid connector is the probable cause of your fuse blowing.

Replacement connectors are here:

Motorcycle 6.3mm - 250 Connector and Terminals

Here is a recent thread related to that connector:

https://www.mvagusta.net/forum/153-g...ed-melted.html
Thanks for the tips. I'm getting a replacement connector from Pete (pittmeister), he's taking the loaner blue SPU and conveniently had some spare connectors I needed. Once I get it I'll button everything up and make sure the spades are tightened. I'm going to do a round of checking for a short like Noel suggested, see if that turns anything up before I start it up and see what happens.

Bike had started fine, but charging light came on almost immediately and it was reading at 11-12V across the battery terminals regardless of engine speed. Is it possible a failing charging system could have blown the 40A fuse?

chris chandler
2004 Brutale S
chandler325i is offline  
post #9 of 10 (permalink) Old 07-16-2019, 09:39 PM
Old Wing Nut
 
esq'z me's Avatar
 
Join Date: Aug 2007
Location: Marietta, GA
Posts: 18,282
Send a message via Skype™ to esq'z me
Only if it was shorted out....
silentservice703 likes this.

I used to be fast....now I just dream about it.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

'08 910R (Gina), '04 F4 SPR #275 Track Bike (Lola), YSR50 (The Rabbit), '71 CB100 (Lil' Red), '75 RD350C (Orange Bird) restoration project, '70 Suzuki F50 (Baby Blue)
esq'z me is offline  
post #10 of 10 (permalink) Old 07-22-2019, 09:08 AM Thread Starter
Established Member
 
chandler325i's Avatar
 
Join Date: Jul 2014
Location: Lost Angeles, CA, USA
Posts: 191
back to the diode

Getting this thread back on track: yes, the diode can be tested without removing it. Unplug the SPU, ECU, and dash. Might not need all three, but that's where the orange/black and blue/yellow wires go, and since I already have my tank off, I disconnected them all.

To pursue additional charging system/start relay questions, I'll post on a more appropriate existing thread (edit: posted HERE)

chris chandler
2004 Brutale S

Last edited by chandler325i; 07-22-2019 at 06:32 PM. Reason: link to relay thread
chandler325i is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to use all of the features of the MVAgusta.net site, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome