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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Houndbrick on May 30, 2018, 05:52:09 PM

Title: No neutral light after clutch sensor wires shorted out
Post by: Houndbrick on May 30, 2018, 05:52:09 PM: 95 K75

The two yellow wires to the clutch sensor on the grip shorted out on me today thanks to some loose zip ties.

Now my neutral light does not illuminate and the bike only starts with the clutch lever pulled in. Gear indicator still works. I also blew the top fuse for the instrument cluster on the exterior fuse block. (7.5 amp). I am assuming once I get the N light working I will be able to start the bike w/o engaging the clutch.

your thoughts are much appreciated
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: johnny on May 30, 2018, 05:57:08 PM: greetings...

help me understand...

moto in neutral... wont start with clutch out... butts will start with clutch in...

moto in any gear 1 to 5... wont start with clutch out... butts will start with clutch in...

is that right...

j o
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: rbm on May 30, 2018, 06:00:10 PM: Can you confirm with certainty that you were always able to start the bike in neutral without use of the clutch switch prior to this accident?

If so, it is highly likely that V10 (the BD370 transistor) on the neutral detect board (http://www.motobrick.com/index.php/topic,10566.0.html) has blown. You'll either need to repair that board or purchase a new one.
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: Houndbrick on May 30, 2018, 06:03:06 PM: Quote from: johnny on May 30, 2018, 05:57:08 PM
greetings...

help me understand...

moto in neutral... wont start with clutch out... butts will start with clutch in...

moto in any gear 1 to 5... wont start with clutch out... butts will start with clutch in...

is that right...

j o

I have yet to try starting it in gear with the clutch lever out. But it will only start with clutch lever pulled. Before as long it was neutral you could start it w/o touching the clutch lever. I pulled apart the instrument cluster and tested the N bulb. It’s still good
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: johnny on May 30, 2018, 06:23:28 PM: greetings...

did you have 12v at the n bulb in neutral...

j o
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: Houndbrick on May 30, 2018, 08:26:08 PM: I don’t have power to the light. My low fuel light is now one too. I’ve got plenty of fuel. I’ve looked over the back of the gage cluster and noticed a small amount damage. Not sure if this is from the short. Look to the left of the main connecter.
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: Houndbrick on May 30, 2018, 08:54:09 PM: Quote from: Houndbrick on May 30, 2018, 08:26:08 PM
I don’t have power to the light. My low fuel light is now one too. I’ve got plenty of fuel. I’ve looked over the back of the gage cluster and noticed a small amount damage. Not sure if this is from the short. Look to the left of the main connecter.

I’m sorry. It’s not the low fuel light it’s the other yellow light to the right. Not sure what it is for...
Title: Re: No neutral light after clutch sensor wires shorted out
Post by: rbm on May 30, 2018, 09:58:31 PM: The light that is lit in your follow-on post is the fast idle (choke) light. Is your bike equipped with a switch on the throttle body frame, near the throttle position indicator? The reason I ask is because BMW stopped equipping K75's with that switch around 1988/89 and yours is a 95 meaning the switch and possibly bulb are not there.

As for the damage to the flexible circuit inside your instrument cluster, it certainly can be the cause of this problem. Is your gear indicator working at the moment but not the neutral light nor the start enable feature? If the answer is "yes", then see if you have continuity between the cathode of the diode and Pin 5. If no continuity, then the traces on the flexible circuit are damaged and start enable will not function.