'99 M900 ignition switch problem

tbyte · May 06, 2015, 07:12:44 AM

It took regular screws. I do not recall the size.

Yes, I meant the two screws in the back of the unit. I could jump her at the coupling to get her started and everything else seemed to be working plus with the jiggling key fixes I was pretty certain it was the ignition switch. So I had nothing to lose by drilling the screws out. I did not have spare to swap in and test.

Destructobot · May 06, 2015, 05:22:08 PM

Ok - so what is supposed to happen at the relay when I turn the key? Is it just connectivity across a couple of the other pins?

ducpainter · May 06, 2015, 05:27:52 PM

Quote from: Destructobot on May 06, 2015, 05:22:08 PM
Ok - so what is supposed to happen at the relay when I turn the key? Is it just connectivity across a couple of the other pins?

howie knows...

Howie · May 06, 2015, 10:10:55 PM

A relay is nothing more than a remote elector-mechanical switch. On a typical Bosch type 4 prong relay 85 (usually the trigger from your input, in this case the ignition switch) and 86 (ground) connect a winding, creating an electromagnet. Either terminal can be a trigger. 30 is power. When the winding is powered, a set of contact points are closed allowing power to flow through 87 to the component(s) you want to operate.

https://www.bing.com/images/search?q=bosch+4+prong+relay&view=detailv2&id=0FF60E10ADE81F693F59B54887A1397006F5CD4D&selectedindex=58&ccid=gkbLmGrp&simid=607994398461528049&thid=JN.93oU6CMYYp%2FDD1Sk22Ho4g&mode=overlay&first=1

Destructobot · May 07, 2015, 11:07:00 AM

So if my switch is working correctly, I should get power at 85 when the key is on, but not when it's off?

Howie · May 07, 2015, 01:00:42 PM

Yes.

Destructobot · May 11, 2015, 10:46:20 AM

Turns out there isn't power at 85. It must have been a fluke that it worked the first time I tested it. Other than the ignition switch itself, what lies between the switch and relay that could cause a problem?

Howie · May 11, 2015, 12:19:59 PM

Wires. Common is a fractured wire coming down the head tube.

Destructobot · August 29, 2015, 04:15:16 PM

I finally got around to tracking down the gremlin, but have hit some snags. First, I'm working off this diagram: http://www.ducatimonsterforum.org/index.php?topic=64720.0 It appears to be correct - wire colors seem to match up with what I see on my bike.

There is NOT power at 85 with the key on. 86 to ground continuity is good. Starts with the key on and 30 jumped to 87. Maybe even with the key off, didn't try that.

Pulled the ignition switch out today. Key off - continuity on pins with blue and white wires, no continuity on the other two pairs of pins. Key on and that all flips -other two pairs have continuity.

The Orange and blue wire going to pin 85 at the relay HAS continuity with the same colored wire at the white connector that attaches to the ignition switch. I presume the other side of that connector (red wire) should be 12v, to then send power to pin 85 when the ignition is on? If so, that's the problem - no continuity between that red wire terminal and the positive post on the battery. I'm guessing that somewhere between that pin and the battery a wire is cracked.

Do I have my head wrapped around the problem correctly? I don't want to start unwrapping wire until I know where I'm headed.

Also, would it cause a problem to just wire up a jump across 30 and 87 and hide a switch for it underneath somewhere? I'm not selling the bike any time soon, so I don't care if it's a bit rigged, I just want it to work.

Destructobot · August 31, 2015, 07:48:05 PM

Now I'm thoroughly confused. Connections from the relay to everywhere else are good (86 to ground, 87a to pin 3 of the switch, 85 to pin 6), ignition switch works, but I still don't have power at 85 when the key is on. Any ideas? Kill switch problem?

Howie · August 31, 2015, 09:52:48 PM

You should have continuity between terminals 3and 6 on the switch side of the connector with the key on. If not, you have a bad switch. Yes, you could run a new wire and a toggle switch. The wire would nee do come off a fused circuit and you have to remember to shut it off. A bright LED would help. Me? I would fix it the right way.

This has been going on since last October? A good shop might make sense so you can

Destructobot · September 01, 2015, 11:52:34 AM

I never really worked on it until this week. Installed the switch last night, works fine. Yes I'd definitely like to fix it correctly, but I'd also like it to not be a paperweight in the meantime. The LED's in the indicator panel do just fine to remind me to turn it off.

I tested the ignition switch, it works correctly. I'm just not figuring out what could cause no power at 85, based on the diagram.

Howie · September 01, 2015, 06:18:33 PM

A quick and easy test. Run jumper wire from terminal 6 on the switch to 85. Got power? Bad wire between the switch and relay. Another idea. Get someone with some knowledge, less than yours is OK, to work with you. That person might see something you are missing. Most of us have spent time diagnosing a fuel problem and discovering after many hours that the problem was an empty fuel tank.

Destructobot · September 02, 2015, 06:31:31 AM

I checked all the connections between the switch and relay for continuity, and they were good. I didn't try jumping it it like that though, I'll give it a shot.

Destructobot · September 02, 2015, 03:18:44 PM

MYSTERY SOLVED!

I figured out that the old relay and new relay don't behave the same. Popped the old one back in, and occasionally it would work. The times it doesn't work, the right tap on the relay makes it come to life. Long story short - the off the shelf relay I got from O'Reilly's must not be a direct replacement. Going to order one of these and hopefully be done with it - - http://store.proitalia.com/ducati-oem-starter-relay-40a

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'99 M900 ignition switch problem