Ducati Monster Forum

Moto Board => Tech => Topic started by: Two dogs on February 05, 2012, 10:17:29 PM

Title: Relay failure
Post by: Two dogs on February 05, 2012, 10:17:29 PM
I have had an annoying intermittent electrical gremlin that hopefully has been solved.
My wife's 695 broke down several times , the latest  we had to van the bike.
After many hours of checking every connection and wires , and confusing computer read outs and
replacing the battery........ resulted in make the beast with two backs all  [bang]
One of the consistent was an injector fault , checking the wire between power and injector
we prized open the relay and found the copper wire coil was discolored/burnt ,what we think was happening
was the ability for the relay to hold the switch closed during running resulting in the random failure.
As insurance I also replaced the relay beside it to the fuel pump.
Phone pic not the best but you can just see the slight burn discolor through the middle of the coil.
So far so good.  [drink]
Anyone else had a similar failure with relays ?
I am assuming this would not be a common fault.
Would these relays be manufactured in Italy or China ?

(http://i239.photobucket.com/albums/ff57/ohana181/Lumin-Small.jpg)
(http://i239.photobucket.com/albums/ff57/ohana181/Lumin-Big.jpg)
Title: Re: Relay failure
Post by: WTSDS on February 05, 2012, 11:21:22 PM
Never happened to me but there have been DMF posts on such failures so I have two spares tucked in near the battery, and made up a small jumper wire just in case. Dunno where they are made, available quite cheap at auto-electrics shops.

Title: Re: Relay failure
Post by: Speeddog on February 05, 2012, 11:27:14 PM
I've seen a couple failures, bu that's all.
Title: Re: Relay failure
Post by: battlecry on February 06, 2012, 07:48:27 AM
I've had two fail and like WTSDS, I carry two spares and a jumper wire, kinda like wearing suspenders and a belt.  I'm using a PCIII and it takes its power from the injector pulse.  I do not know if the extra fueling could be changing the current draw beyond its margin. 
Title: Re: Relay failure
Post by: Thermite on February 06, 2012, 08:08:33 AM
Relays are outsourced so it's almost certainly not from Italy.  It may just be the picture but that one doesn't look that bad.  My guess is if you put 12 volts on the coil contacts you'll get to see the switchgear close.  Do you have a multimeter?  Check the resistance of the coil and compare it to data you can easily get online for that relay.  The reason I say to do this that you may not have solved your gremlin problem yet.

If you're concerned with quality look for a Tyco replacement.

Battlecry,  the load on the relay goes through the switchgear not the coil.  The contacts of the switchgear are certainly rated high enough to handle whatever you have downline and also will handle more than the fuse.
Title: Re: Relay failure
Post by: battlecry on February 06, 2012, 09:08:47 AM
The Bosch relays are specced for 15A at 85C, same as the Tycos.  Fuel pump with clean filter draws 5A, ignition around 4A,  ECU around 2A.  My wiring diagram shows the relay also feeds the injectors, their hold current can be in the order of 1/2A, coil saturation even higher.  A few more amps from a clogged fuel filter or a higher temperature and you can be close to the rated load.   Maybe there is enough margin, I do not know.   
Title: Re: Relay failure
Post by: suzyj on February 06, 2012, 11:53:46 AM
All things electrical are connected together. Your faulty battery probably caused the coil in the relay to overheat.

Hope you replaced the battery with a sexy lithium one.