Ducati Monster Forum

Moto Board => Tech => Topic started by: Norcoastal on June 02, 2020, 05:30:29 PM

Title: Wire Question
Post by: Norcoastal on June 02, 2020, 05:30:29 PM
Hey everyone, I’ve been restoring a 2000 750 for the past few months and I’m down to the wire harness.

When is disassembled the bike, I labeled everything on the harness. There were two wires that weren’t attached to anything therefore I had nothing to label them with.

One looks like a ground wire, it’s thick like a battery cable with a loop end on it. The other is a two pronged connector.

I put a probe on the thick wire and to my surprise, it’s a constant hot when the key is on. The two prong connector has one hot side when the key is on. Because it’s a thick wire so I have to assume that it carries a heavy load like a starter, but the starter solenoid has the two wires on it that are supposed to be there. One from the engine and the other to the positive on the battery.

Can anyone take a look at the below pictures and let me know if you know where they attach?

(https://i.postimg.cc/50F9fQ9H/AEFF6576-58-BA-42-D1-9776-A65644-F83327.jpg) (https://postimg.cc/zb8YjBg5)lowrider wallpaper (https://suwalls.com/cars/lowrider)
Title: Re: Wire Question
Post by: stopintime on June 02, 2020, 05:49:09 PM
Where do they come from?
Title: Re: Wire Question
Post by: Speeddog on June 02, 2020, 09:30:15 PM
Difficult to judge scale from that pic, can you do another with a common item for scale?
Title: Re: Wire Question
Post by: greenmonster on June 03, 2020, 05:00:35 AM
Do you have a battery ground to engine cable?
If not, the thick one cold be it.

The other do look like solenoid cable.
Title: Re: Wire Question
Post by: Duck-Stew on June 03, 2020, 05:14:18 AM
IZ_ picture, but I’ll take a stab:

Small rectangular connector is to the starter solenoid.  This connector provides the low amperage power and ground to pull in the solenoid contact.

Large wire which goes hot when connected to the battery is the battery side of the solenoid.  So, basically, you have to get under the battery box and mess with possibly the worst positioned oem solenoid ever.

Just a guess about the large wire.  The small white-ish rectangular one I’m sure about.
Title: Re: Wire Question
Post by: Pinion on June 03, 2020, 01:17:38 PM
Quote from: Duck-Stew on June 03, 2020, 05:14:18 AM
IZ_ picture, but I’ll take a stab:

Small rectangular connector is to the starter solenoid.  This connector provides the low amperage power and ground to pull in the solenoid contact.

Large wire which goes hot when connected to the battery is the battery side of the solenoid.  So, basically, you have to get under the battery box and mess with possibly the worst positioned oem solenoid ever.

Just a guess about the large wire.  The small white-ish rectangular one I’m sure about.

I think your spot on
Title: Re: Wire Question
Post by: Norcoastal on June 03, 2020, 05:11:20 PM
I think the solenoid plug makes sense by everything I’m looking at, but I don’t remember seeing a plug on the solenoid to plug it into.

I’ll remove it this weekend and take a closer look. I agree that the black wire looks like a ground, but when I tested it, it has 12v coming out of it. I guess a ground has juice also as it completes the circuit.

Thanks everyone, wiring isn’t my strength, but I’m learning. I know just enough to get myself in trouble. The Power Probe has been helpful too.

I also just bought a Haynes Manual, that should help me also.


Thanks again!!!
Title: Re: Wire Question
Post by: Norcoastal on June 03, 2020, 05:16:02 PM
Quote from: Duck-Stew on June 03, 2020, 05:14:18 AM
IZ_ picture, but I’ll take a stab:

Small rectangular connector is to the starter solenoid.  This connector provides the low amperage power and ground to pull in the solenoid contact.

Large wire which goes hot when connected to the battery is the battery side of the solenoid.  So, basically, you have to get under the battery box and mess with possibly the worst positioned oem solenoid ever.

Just a guess about the large wire.  The small white-ish rectangular one I’m sure about.

The solenoid already has two wires connected to it. One goes to the starter, and the other goes to a pigtail where the red positive wire is attached to the battery.

Doesn’t make sense that the large wire is a positive to the battery. But I have no idea what I’m taking about so don’t take whatever I say like I know what is right.
Title: Re: Wire Question
Post by: Norcoastal on June 03, 2020, 05:22:37 PM
Here’s a picture to show scale. Also a picture that shows the positive connected to the junction that has a thick wire going to the solenoid.

(https://i.postimg.cc/2ybgPvxy/45-CAAB47-3599-4456-930-A-08-C68-C363107.jpg) (https://postimg.cc/wRzWN1ZY)

(https://i.postimg.cc/zvs45Bdj/544-AA66-A-8-C81-421-B-916-D-42-F837-EC9-FD8.jpg) (https://postimg.cc/N2xdkgv9)
Title: Re: Wire Question
Post by: Duck-Stew on June 03, 2020, 08:07:52 PM
If the other end of ghat large black wire plugs into the black plastic splitter on the positive cable the it is FOR SURE the hot (always hot) lead from the battery to the solenoid.

Also, if you have questions of this nature, is there anyone local to you who knows this sort of stuff who can lend a hand?!?  This is, after all, the internet.
Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 10:29:41 AM
Thanks and you’re right, this is only the internet, but you be surprised how much info I learn on these forums!
Title: Re: Wire Question
Post by: Duck-Stew on June 04, 2020, 01:33:59 PM
Quote from: Norcoastal on June 04, 2020, 10:29:41 AM
Thanks and you’re right, this is only the internet, but you be surprised how much info I learn on these forums!

Agreed, but check things thoroughly before making final connections.  I’m not going to come over and fix the bike, or be held liable.  Let me know if I can help further.
Title: Re: Wire Question
Post by: Speeddog on June 04, 2020, 02:23:59 PM
This is a pic of a '98 M750 harness.

(https://live.staticflickr.com/65535/49971592631_55b2953a9a_o.jpg) (https://flic.kr/p/2j8Ptvi)


The harness ground connection that is bolted underneath the battery is shown in the pic, and is twist-tied to the ground wire that goes from battery negative to the same bolt location.

You can see the white 2-pin plug inserted into the starter solenoid.
Title: Re: Wire Question
Post by: dbran1949 on June 04, 2020, 02:46:14 PM
just a quick note to say I don't recognize any of the wiring, but if you are reading +12 VDC on that large black wire with the ring-tongue terminal do NOT connect to ground
Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 04:24:59 PM
Quote from: Speeddog on June 04, 2020, 02:23:59 PM
This is a pic of a '98 M750 harness.

(https://live.staticflickr.com/65535/49971592631_55b2953a9a_o.jpg) (https://flic.kr/p/2j8Ptvi)


The harness ground connection that is bolted underneath the battery is shown in the pic, and is twist-tied to the ground wire that goes from battery negative to the same bolt location.

You can see the white 2-pin plug inserted into the starter solenoid.

That sure looks like my plug. I’m going to take the air box off over the weekend and check the solenoid.

Thanks for the picture.
Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 04:25:43 PM
Quote from: Duck-Stew on June 04, 2020, 01:33:59 PM
Agreed, but check things thoroughly before making final connections.  I’m not going to come over and fix the bike, or be held liable.  Let me know if I can help further.

No worries, no liability, this is all on me. 
Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 04:28:31 PM
Quote from: dbran1949 on June 04, 2020, 02:46:14 PM
just a quick note to say I don't recognize any of the wiring, but if you are reading +12 VDC on that large black wire with the ring-tongue terminal do NOT connect to ground

I’ll check it again before I make a connection. I’m also getting the Haynes Manual any day now and I’m sure that will help.

Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 04:34:00 PM
I know this isn’t very helpful, but the two wires in question are in yellow. 

According to the vague reference, the plug goes to the solenoid. The other is the one in question.

Does this help any, or just compound the question?

(https://i.postimg.cc/9MH6NLDg/0378-D424-AFA0-4806-BB77-B08-F1-CB5883-C.jpg) (https://postimg.cc/8FwX7BBL)cheapest gas station around me (https://gasstation-nearme.com/cheap)
Title: Re: Wire Question
Post by: Speeddog on June 04, 2020, 05:07:24 PM
Quote from: dbran1949 on June 04, 2020, 02:46:14 PM
just a quick note to say I don't recognize any of the wiring, but if you are reading +12 VDC on that large black wire with the ring-tongue terminal do NOT connect to ground

I'm pretty damn sure the ground I showed in my picture is the *entire ground* for the whole bike, except for the starter motor.

If the positive wire is connected to the battery, and that ground wire is floating in thin air, it'll show 12v on it.
Title: Re: Wire Question
Post by: Norcoastal on June 04, 2020, 05:10:35 PM
Quote from: Speeddog on June 04, 2020, 05:07:24 PM
I'm pretty damn sure the ground I showed in my picture is the *entire ground* for the whole bike, except for the starter motor.

If the positive wire is connected to the battery, and that ground wire is floating in thin air, it'll show 12v on it.

I really appreciate your advice. Thank you.
Title: Re: Wire Question
Post by: Norcoastal on June 05, 2020, 09:20:10 AM
Quote from: Speeddog on June 04, 2020, 05:07:24 PM
I'm pretty damn sure the ground I showed in my picture is the *entire ground* for the whole bike, except for the starter motor.

If the positive wire is connected to the battery, and that ground wire is floating in thin air, it'll show 12v on it.

Hey Speeddog quick question,

That picture that you show of your “entire ground”, neither of the two wires that come off of the solenoid are that ground you show connected to your negative battery cable correct?

Can’t see what they are. I assume one goes to the starter and the other to the positive. Just double checking.

Thanks again!!!
Title: Re: Wire Question
Post by: Speeddog on June 05, 2020, 12:24:13 PM
Quote from: Norcoastal on June 05, 2020, 09:20:10 AM
Hey Speeddog quick question,

That picture that you show of your “entire ground”, neither of the two wires that come off of the solenoid are that ground you show connected to your negative battery cable correct?

Can’t see what they are. I assume one goes to the starter and the other to the positive. Just double checking.

Thanks again!!!


Correct, the two large wires shown in my pic attached to the solenoid, one connects to the positive battery terminal and the other to the starter.

Your harness has a large wire going from the starter solenoid to the connector on the end of the large wire that attaches to the positive battery terminal.

Your post of the parts diagram has correctly ID'd the wires with the yellow highliter.
Title: Re: Wire Question
Post by: Norcoastal on June 05, 2020, 03:49:03 PM
Thanks Speeddog

I put the power probe on it and it’s 100% a ground.

I connected one end to a ground and the other to the lead in question and there is zero current.

Also the power probe detects a ground with a green light and hot with a red light.

Thank you all for your help, MUCH APPRECIATED!!!

Now I have to remove the air box again and the ignition to get to the solenoid to connect the two prong plug.

One last question, is that two prong plug the mechanism that starts the starter? Meaning is that plug connected to the start button? That would make sense.

(https://i.postimg.cc/hvFxLJ6z/0-B985-FF8-18-CE-441-F-A33-F-F7-C5-E88-C38-BC.jpg) (https://postimg.cc/tZ5YygXp)
Title: Re: Wire Question
Post by: ducpainter on June 05, 2020, 04:09:27 PM
Quote from: Norcoastal on June 05, 2020, 03:49:03 PM
Thanks Speeddog

I put the power probe on it and it’s 100% a ground.

I connected one end to a ground and the other to the lead in question and there is zero current.

Also the power probe detects a ground with a green light and hot with a red light.

Thank you all for your help, MUCH APPRECIATED!!!

Now I have to remove the air box again and the ignition to get to the solenoid to connect the two prong plug.

One last question, is that two prong plug the mechanism that starts the starter? Meaning is that plug connected to the start button? That would make sense.

(https://i.postimg.cc/hvFxLJ6z/0-B985-FF8-18-CE-441-F-A33-F-F7-C5-E88-C38-BC.jpg) (https://postimg.cc/tZ5YygXp)
Yes.