Does not starts in gear

Discuss all things 1970 & later Airheads right here.
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Does not starts in gear

Post by cpazambrana »

But based upon the second youtube video above, even if the diode is bad, the clutch switch should provide the a ground and allow the starter to spin, so I don't believe the diode is the issue. On the '75, and I believe the '83 as well, the clutch switch wires go into the headlight shell. One wire provides power in and the other goes to ground (brown). [b]The wires from the clutch switch connects to a plug that is exposed in the down side of the triple tree. [/b] See photo. From there, it goes into the harness that goes below the tank.

Verify you have a good ground, and that the other wire has good power. If you pull the ground wire off, verify you get 12v at that wire every time you pull the clutch and 0v when you release it. If you do, it's probably a ground problem. If you don't, then verify the power source the other wire is connected to in the fuse block.

I then went to the plug that is located on the left side of the bike, behind the side cover and by the battery. This plug connects the cables from the main harness to the neutral switch and to the oil pressure switch. I unplugged it and tested for current and it has 12.26 volts in both terminals (the brown/green and the brown/black). This did not change when I pulled the clutch lever in. I cleaned the plug to eliminate a bad connection.

I then went to the neutral switch and was able to touch the two terminals to test continuity. Weird thing is that it showed continuity of 0.00 in Neutral and .003 when in gear. Is this normal?

I did not take the tank out so I didn't test the diode. I will do this in the weekend after I have a bit more feedback.
Attachments
BMW Plug 2.jpg
BMW Plug 2.jpg (46.98 KiB) Viewed 1033 times
BMW Plug 1.jpg
BMW Plug 1.jpg (60.25 KiB) Viewed 1033 times
BMW 1.jpg
BMW 1.jpg (51.65 KiB) Viewed 1033 times
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Where's Rob F when you need him?

Post by cpazambrana »

gspd wrote: Thu Apr 29, 2021 12:57 am Sounds like a clutch switch circuit fault.
On some models the starter button powers the starter relay, and on others the starter button grounds the relay.
Need a wiring diagram specific to that bike to diagnose.
Here it is.
Attachments
BMW Wiring Diagram.jpg
BMW Wiring Diagram.jpg (74.77 KiB) Viewed 1032 times
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Does not starts in gear

Post by gspd »

Very basic circuit tracing, no rocket science here.
- Make sure the brown wire of your clutch switch is well grounded.
- Assure there is continuity between the other clutch switch wire (brown/yellow) and the same color wire that comes from the starter button. They join at the circuit board 85b near the diode.

There is a break somewhere in this circuit, usually where the harness is stretched or rubs while turning the bars, or maybe at the actual board. Might be corrosion at a connector. Once you find it you'll see how simple it was ;)

BTW - Did you test your new clutch switch for proper functioning while it was actually installed on the bike?
Sometimes a slight glitch or misalignment with the lever or housing can prevent even a new switch from functioning properly.

You asked:
I then went to the neutral switch and was able to touch the two terminals to test continuity. Weird thing is that it showed continuity of 0.00 in Neutral and .003 when in gear. Is this normal? It's normal, but that's not how you test it!!!!
From what you said the bike was doing, I'm confident that your neutral switch is OK , although you never confirmed that your neutral light is working, I'm assuming it is because you said somewhere that you had 12v at one terminal of the neutral switch which can only happen if the bulb is working.
If you insist on testing it anyway, disconnect the 2 wire connector (the one that also goes to the oil light) and connect your meter between that brown/black neutral switch wire and any good ground. neutral=closed circuit, in gear=open circuit means it's good.
Last edited by gspd on Thu Apr 29, 2021 9:10 pm, edited 1 time in total.
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Does not starts in gear

Post by cpazambrana »

gspd wrote: Thu Apr 29, 2021 8:41 pm Very basic circuit tracing, no rocket science here.
- Make sure the brown wire of your clutch switch is well grounded.

How exactly do I do this? I checked for current in the plug where the clutch switch connects and the is no current there. Or do I need to push the starter button while checking this?

- Assure there is continuity between the other clutch switch wire (brown/yellow) and the same color wire that comes from the starter button. They join at the circuit board 85b near the diode.

I’ll have to dismount the tank and which I’ll do this weekend.

There is a break somewhere in this circuit, usually where the harness is stretched or rubs while turning the bars, or maybe at the actual board. Might be corrosion at a connector.

BTW - Did you test your new switch for proper functioning while it was actually installed on the bike?
Sometimes a slight glitch or misalignment with the lever or housing can prevent even a new switch from functioning properly.

I tested the switch for continuity. 1 to 0.00 when the clutch lever is pulled. But there is no current in the terminal where it connects.

You asked:
I then went to the neutral switch and was able to touch the two terminals to test continuity. Weird thing is that it showed continuity of 0.00 in Neutral and .003 when in gear. Is this normal? NO IT IS NOT!!!
From what you said the bike was doing, I'm confident that your neutral switch is OK , although you never confirmed that your neutral light is working, I'm assuming it is because you said somewhere that you had 12v at one terminal of the neutral switch which can only happen if the bulb is working.
If you insist on testing it anyway, disconnect the 2 wire connector (the one that also goes to the oil light) and connect your meter between the brown/black wire and any good ground. neutral=closed circuit, in gear=open circuit means it's good.
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Does not starts in gear

Post by cpazambrana »

gspd wrote: Thu Apr 29, 2021 8:41 pm Very basic circuit tracing, no rocket science here.
- Make sure the brown wire of your clutch switch is well grounded.
- Assure there is continuity between the other clutch switch wire (brown/yellow) and the same color wire that comes from the starter button. They join at the circuit board 85b near the diode.

There is a break somewhere in this circuit, usually where the harness is stretched or rubs while turning the bars, or maybe at the actual board. Might be corrosion at a connector.

BTW - Did you test your new switch for proper functioning while it was actually installed on the bike?
Sometimes a slight glitch or misalignment with the lever or housing can prevent even a new switch from functioning properly.

You asked:
I then went to the neutral switch and was able to touch the two terminals to test continuity. Weird thing is that it showed continuity of 0.00 in Neutral and .003 when in gear. Is this normal? NO IT IS NOT!!!
From what you said the bike was doing, I'm confident that your neutral switch is OK , although you never confirmed that your neutral light is working, I'm assuming it is because you said somewhere that you had 12v at one terminal of the neutral switch which can only happen if the bulb is working.
If you insist on testing it anyway, disconnect the 2 wire connector (the one that also goes to the oil light) and connect your meter between the brown/black wire and any good ground. neutral=closed circuit, in gear=open circuit means it's good.
I did this. Connected the brown/black to ground and the neutral light went on and starter worked. The curious thing is that both the brown black and the brown green had current regardless of whether the clutch is pulled or not. Btw the neutral light does work normally.
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Does not starts in gear

Post by gspd »

- Make sure the brown wire of your clutch switch is well grounded.

You asked: How exactly do I do this?

You're making this simple fix way too complicated.
Do you have a test light like this? with a pointy tip?
It's all you need to test all your switches and wiring and fix this issue.

It can be done with your meter but it'll be waaay easier for me to remotely and comprehensively walk you through each step with a test light. It's a simple GO/NO GO issue. Specific voltages and resistances are not an issue in this particular situation. (sorry rob F) :cry:
You don't have to remove your gas tank.(for now)
You do have to remove your headlight to access the circuit board inside.
Attachments
shopping.png
shopping.png (5.58 KiB) Viewed 1017 times
shopping.png
shopping.png (5.58 KiB) Viewed 1017 times
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
Rob Frankham
Posts: 1214
Joined: Thu Aug 26, 2010 2:11 pm
Location: Scotland UK, 20 miles from civilisation up a dead end road!
Contact:

Re: Does not starts in gear

Post by Rob Frankham »

gspd wrote: Thu Apr 29, 2021 9:55 pm
Specific voltages and resistances are not an issue in this particular situation. (sorry rob F) :cry:
I have no real argument with that but I would insert the word 'probably' between 'are' and 'not' ;) .

Rob
ImageImageImage
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Does not starts in gear

Post by cpazambrana »

gspd wrote: Thu Apr 29, 2021 9:55 pm - Make sure the brown wire of your clutch switch is well grounded.

You asked: How exactly do I do this?

You're making this simple fix way too complicated.
Do you have a test light like this? with a pointy tip?
It's all you need to test all your switches and wiring and fix this issue.

It can be done with your meter but it'll be waaay easier for me to remotely and comprehensively walk you through each step with a test light. It's a simple GO/NO GO issue. Specific voltages and resistances are not an issue in this particular situation. (sorry rob F) :cry:
You don't have to remove your gas tank.(for now)
You do have to remove your headlight to access the circuit board inside.
Bear with me here my friend. I rebuild that Yamaha Seca engine and transmission after I bought the whole bike in pieces. But electronics are my weakness. I do have one of those test lights somewhere in my garage. I will take the headlight off tomorrow and share some pictures here so you can guide me through it. I’m thankful for your time and patience. Hopefully this is something simple. Happy Friday.
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Does not starts in gear

Post by gspd »

cpazambrana, if you get a test light and remove your headlight it should be a very simple procedure and I'd be happy to walk you through it.
You need a fine needle tip probe capable of piercing wire insulation.
Oh, and to the purists...Don't worry, we won't be punching holes all over the harness, just a few strategically placed and imperceptible pin pricks to check for a pulse.
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
cpazambrana
Posts: 48
Joined: Wed Apr 14, 2021 12:59 pm

Re: Does not starts in gear

Post by cpazambrana »

Ok. I have the test light and remove the headlight. It looks scary all the stuff packed there. See photo. Connector box with the two fuses is all the way back. What I should looking for?
Attachments
69C2B142-EA61-4800-A0C8-DD73597D24F7.jpeg
69C2B142-EA61-4800-A0C8-DD73597D24F7.jpeg (89.3 KiB) Viewed 930 times
1983 BMW R80RT
1976 BMW R60/6
Still looking for a Honda CB77 Superhawk
Post Reply