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Discussion Starter #1
Does anyone know where the power lead for the light bulb of the neutral switch comes from? Seems all of the wiring diagrams (even the 2001) show the two-wire switch instead of the one-wire switch.

Assuming the single wire switch acts as a ground, the power must come from somewhere, and I'm not getting any power to that light at the front harness. Thanks!
 

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Discussion Starter #3
Thanks for the illustration, but I already have that one. If you look at the neutral switch in the diagram, it shows a power and a ground coming out, which is incorrect for the 2001 year. It's a single wire switch (ground). So that other wire to the bulb must be getting power from somewhere.
 

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Thanks for the illustration, but I already have that one. If you look at the neutral switch in the diagram, it shows a power and a ground coming out, which is incorrect for the 2001 year. It's a single wire switch (ground). So that other wire to the bulb must be getting power from somewhere.
I might be confusing it, but... I think it comes from the very back and toward the bottom of the engine case below where the oil breather is. My rear brake line runs right across the place.
 

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This is what I ran into when I install my 1998 916 engine with 2001 996 wiring harness. The pre-2001 model uses 2 wire neutral switch, later model use 1 wire switch. Both are ground type switch, it completes ground circuit when engaged.

The only different between the 2 styles is, early model use 1 of the 2 wire as ground, later model use the switch threads as ground. Both have input wire coming from main harness, early model use bullet connectors, later model use weatherproof clip-on connector.
 

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Discussion Starter #6
Thanks for the help fellas, but I think I'm not being clear. I'm trying to figure out where the hot lead for the neutral light comes from. The ground obviously comes from the switch. But i'm not getting anything from the positive side of the light bulb.
 

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Wiring diagram in Haynes manual shows 1 wire switch for '01 996.

+ve feed from fusebox.

See attached scan, HTH
 

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Does anyone know where the power lead for the light bulb of the neutral switch comes from? Seems all of the wiring diagrams (even the 2001) show the two-wire switch instead of the one-wire switch.

Assuming the single wire switch acts as a ground, the power must come from somewhere, and I'm not getting any power to that light at the front harness. Thanks!
Doesn't the neutral switch complete the circuit, thus turning the light bulb on? if so, then the power going into the bulb, and I am pretty sure the bulb is powered by the same circuit as the rest of the dash lights.

Sorry, I didnt read all the posts before I posted, that hayes manual page is exactly what I was thinking about.
 

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Discussion Starter #9
Wiring diagram in Haynes manual shows 1 wire switch for '01 996.

+ve feed from fusebox.

See attached scan, HTH
Hmm, I've been misreading that same wiring diagram. But that means that maybe the harness with the water temp gauge must be plugged in since that shares the same power as the neutral light, amongst others? Water temp has power, but the neutral light does not...gonna have to investigate some more. Thanks fellas...keep up the ideas..
 

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Discussion Starter #10
Ok the wiring diagram above is right, which is VERY wrong. Here's the situation. The neutral switch is an open/close ground switch. It's grounded to the engine via contact and the wire goes to the light harness (green/yellow) to the bulb. The other side of the bulb has the black ground which is a common ground with some other parts (ie - Temp Gauge Ground and Fuel Pump Ground). So how in the world does a bulb light up with 2 grounds?!?! I'm baffled.....
 

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Ok Mr.CobraR

Look again at the attachment, I'v hilited the wire path. Lets start where power comes in at the fuse. The other sie of the fuse is fed from a relay that closed when the key is turned on. This fuse (+12) feeds several indicators, neutral light being one, its color is LB or light blue NOT black. The other side of the neutral light is the "switch grounded wire" YG yellow Green . The neutral switch [inside the transmission] switches this wire to ground and illuminates the light. Regardless if the neutral switch has one wire [grounds inside the engine] or two wires [grounds through the wiring harness using black] the result is the same. I think your confusion is thinking the power side of the neutral light was black [gnd] and not B+, [+12].

Make Sense?
 

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Discussion Starter #12
I definitely do appreciate your help with that. But my wire coming from the neutral light bulb is not light blue. It's black on one and the other is the g/y wire. I have no light blue wires. So check this out....the black wire going to the light bulb has continuity with the other ground in the oil pressure, tach and water temp wires. This is the grounds (no pun intended...maybe) for my confusion. So I have a black wire which is a common ground with those, just as shown on the wiring diagram, and the g/y wire that goes straight to the neutral switch, which is a ground.

Now, according to the wiring diagram, you're correct in your description, but according to my bike (which had a working neutral light up until this weekend), my neutral light has two grounds and no power.(?) G/Y wire goes to the pin on the upper most right wire on the harness connection (facing the bike, right side harness in the Headlight Bucket) and the black wire that is shared with several other lights (I took the harness sheathing off to verify) goes to the middle wire, bottom row of the same harness.

So I must be missing something somewhere...oh...I need another beer.
 

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Discussion Starter #13 (Edited)
BTW - I have two sets of front wiring harnesses and both are wired the same way...really weird. Maybe I should just cut the black wire on the neutral light and tap it to the 12v feeding one of the others...but I'm still curious.

Let me clarify something. The green/yellow wire going to the bulb is indeed coming from the neutral switch. I made sure of this by continuity test and also by using it as a ground on my voltmeter (and to make sure the bike was indeed in neutral).
 

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Weird, from what you've described It's hard to believe that the light had been working. Check some of the other bulbs on that light blue circuit in the diagram and see if there is a light blue +12 conductor in the harness, if there is maybe it's worth tapping into this and wiring the circuit as depicted, but the mystery would remain as to why the frickin thing was working before.
 

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Discussion Starter #15
Correction, the blue wire is there...goes to the non-functioning battery light...
 

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Weird, from what you've described It's hard to believe that the light had been working. Check some of the other bulbs on that light blue circuit in the diagram and see if there is a light blue +12 conductor in the harness, if there is maybe it's worth tapping into this and wiring the circuit as depicted, but the mystery would remain as to why the frickin thing was working before.
+10000
 

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Correction, the blue wire is there...goes to the non-functioning battery light...
What method are you using to determiine the black [power] wire on the bulb is what you think ground? Ohm meter or voltmeter?
 

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What method are you using to determiine the black [power] wire on the bulb is what you think ground? Ohm meter or voltmeter?
Sorry I see whats happening now..

"black wire going to the light bulb has continuity with the other ground in the oil pressure, tach and water temp wires."

When you put your continunity meter between the black power wire and ground you are actually measuring continunity to ground due the to other indicators and their connection to ground thru the indicator, incandesnsent light bulbs have a low resistance when they are cold, glowing hot the resistance increases, plus there relay coils and such on the other side of the fuse. At this point I assume the transmission switch is ok? To check it simply disconnect the connnect near where it exits the transmission, I'd hate to think you are chasing your tail thinking the problem is electrial up in the cluster when its really electro/mechanical ptoblem in the transmission. There're is a plug somewhere on the transmission where you can adjust the trip point on the neutral switch.
 

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Discussion Starter #19
Well, I gave up and took the blue 12v wire out of the battery light bulb, which our bikes don't use anyway, and swapped it with the black wire going into the neutral bulb...voila. Works now.

BUT, the mystery is still there...how on Earth did it work before?

Just to let you know, I did disconnect the switch, hooked the wire from the harness connection (that hooked up to the switch) to the battery ground and still nothing at the light. (before I swapped the wires). This is as mysterious as Michael Jackson's private life....

Sorry I see whats happening now..

"black wire going to the light bulb has continuity with the other ground in the oil pressure, tach and water temp wires."

When you put your continunity meter between the black power wire and ground you are actually measuring continunity to ground due the to other indicators and their connection to ground thru the indicator, incandesnsent light bulbs have a low resistance when they are cold, glowing hot the resistance increases, plus there relay coils and such on the other side of the fuse. At this point I assume the transmission switch is ok? To check it simply disconnect the connnect near where it exits the transmission, I'd hate to think you are chasing your tail thinking the problem is electrial up in the cluster when its really electro/mechanical ptoblem in the transmission. There're is a plug somewhere on the transmission where you can adjust the trip point on the neutral switch.
 

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I realize this post was long ago but...
Has anyone ever figured out 94CobraR’s issue? I have the exact same scenario on my 996. Neutral light use to work but stopped. No +12V to the neutral light black wire. If I take +12V from another source the the neutral light works when the bike is actually in neutral. Switch is new and works perfect.
I have it working by modifying exactly like 94 CobraR did but want to understand how to fix this properly
Would anyone know what if any relay this light would be on? Maybe this is where lack of +12V is coming from.
 
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