Ducati Monster Forum

03 620

Long story short: the battery was low, connected a battery to jump it, oops connected it backwards, and blew the 40a fuse.

Replaced the 40a fuse.

Now when we connect the jumper battery, it will not start with the start button. The pump primes, everything else seems to have power, but No click from the solenoid.

We jumped the solenoid, and the bike starts, but when we disconnect the jump battery, the bike dies.

I'm going threw the electrical now, but what do you guys/gals think is the problem.

TIA

Maybe the regulator.  While the battery is still connected see what the voltage is at the (bike) battery.  You want 13.5-14.5 volts at 3K RPM.

Threw in a good battery from the other bike, and the start switch didn't work.

Had to jump it at the solenoid, it started, stayed on, and I got 14.25v at 3K RPM.

Cleaned and tested the start switch, and all is good there also.

Any reason why it initially died when I disconnected the the jump battery.  Shouldn't it of stayed on regardless of how low the battery was?

bad solenoid? or got fried?

I tested the solenoid, and that's ok.

But...I should test the harness leading to the solenoid.

I wonder if it's possible for just the start portion of the ECU to get fried, and nothing else...........?

How did you test the solenoid?  Ohmmeter?  Apply power to the wires in the back?  I would remove it from the bike, put an ohmmeter on the two big lugs, apply voltage and ground to the back and look for 0 ohms.

Your solenoid needs the ignition switch, kill switch starter button, computer and related wiring to operate.  Your ignition switch and kill switch work because the bike runs.  The starter button we don't know.  The starter button on your bike is is just a signal to the computer, the computer tells the solenoid to operate.  I don't have a wiring diagram for your bike, so I can't tell you colors or computer pins.

You have two small wires going to the back of the solenoid.  One is ground, one is power.  With the key on a test light or voltmeter should read voltage at both wires when you hit the starter button , but since you tested the solenoid I assume you know that.  My guess is the computer grounds the solenoid since that is the way it usually works with computers. 

The starter button is a simple switch.  When you press the starter button you should have continuity at the connector.  Again, you need a wiring diagram.  Maybe not, there are only four wires, two from the kill switch and two from the starter button.  You know the kill switch part works.

The ECU is probably not fried, they are actually pretty durable.  Unfortunately the only way to diagnose the computer is to eliminate all else or substitute a known good computer. 

Thanks for all the help guys.

Just for reference the motor does start if I complete the + circuit to the starter with the key on.

So the following has been tested:

Regulator 14.25v @ 3K rpm.
Killswitch good.
Start button good.
Harness + to the solenoid  good.
Solenoid clicks good when jumped + & - to the battery.

NOW the issue seems to be the ECU not completing the - circuit to the solenoid regardless if the sidestand is up/down & clutch in out.  All with an indicated neutral.



I can probably bypass the ecu supplying the - to the solenoid, but I think that will by pass all the safety features, and considering this bike belongs to a novice rider, it's probably not the best idea.
 

Just to be sure jump both safety switches and check the solenoid the way I said, with an ohmmeter or supply voltage to the connectors with the solenoid hooked up between the battery and starter.  The contacts in the solenoid could have arced enough to develop resistance although the winding is good.  You could also bypass the computer if you find out which pins are for the solenoid.  This could be as a test or a cheap repair if you don't mind bypassing the safetys.

Thanks Howie.

The solenoid is passing enough current to power the starter when I jump the "small wires" directly to the battery.

I also checked the harness from the ecu to the solenoid and it's good.

Ohm metered the sidestand switch and the clutch switch and they seem good...up to the point where they plug into the harness.

Damn it.   [bang]

Looks like I'm about to bypass the ECU, and give the solenoid a permanent ground, unfortunately I'm pretty sure that will be bypassing all the safeties.  FCUK!  [bang]

Ok, instead of giving the solenoid a permanent ground, I think I'm going to use the clutch switch as the ground making it a permanent clutch in to start circuit.

This way, the clutch in safety is still there for this novice rider.

Thoughts?

TIA

That will work.

There is more than one ground circuit on the Marelli ecu's. If you could figure out where another was you might be able to share it with your starter circuit ground and leave all the safeties intact.

IT LIVES!!!

There were a couple more steps than I was expecting though.

1) Disconnect both wires from the start button.
2) Splice the switch side of the clutch switch to a start button wire.
3) and then splice the solenoid ground to the other start button wire.

From the riders point of view, it starts just the way it did before the cpu got fried.

Only wacky side effect is with the killswitch off, the engine will turn over...but not start.  Otherwise, the killswitch works as normal, and the sidestand safety switch works as normal also.

I could probably wire it so the motor won't turn over with the killswitch off by tapping the killswitch into the series with the clutch switch and the start button, but I'm done with it for now as it's not really a safety issue...it's just wacky.

Schematics and a multi-meter were essential!!!


Thanks for all the help guys.

Some Duc SBK's would act the same re turning over but no fuel pump with the kill switch activated.

Looks like you emulated that.

Nice work.

Fantastic [thumbsup] and [beer]

And the battery is fried.

Looks like this 620 will keep the s2r battery, and the s2r might just get a shorai....

EDIT: Just ordered the Shorai.   :)

Good work in tracking down the problem and coming up with a very decent solution  [thumbsup] [clap].

+1,

well done, good use of the resources available.