Honda Twins banner

1 - 17 of 17 Posts

·
Registered
Joined
·
43 Posts
Discussion Starter #1
Hi Everyone,

Hopefully this is a simple fix or someone can point me in the direction of a sticky that addresses this. Any and all help greatly appreciated!

Here are the symptoms:
No power to lights, starter, horn etc.
Previously, all electrical was in good working order. Nothing electrical was replaced on the bike recently.
Battery showed some signs of sulfating so I replaced it.

Current Battery Reading: 12.8V
Solenoid: 12.8V
Ignition Switch: 12.8V
15A Main Fuse: 12.8V
7A Fuse Tail Light: 0.0V
7A Fuse Headlight: 0.0V

I tried to test the Ignition/Kill Switch continuity by using the B/W wire at the CDI box and the BATT- terminal and got this:

Ignition Off/Run Off = 0.00
Ignition On/Run Off = 0.00
Ignition On/Run On = L
Ignition Off/Run On= L

Fuses all Read: 0.00

So my question is are the 7A fuses supposed to receive power before the bike is on? If so, do I need to replace the fuse holder since the fuses are all good?
I have the FSM but it doesn't really address the fuses other than to say " If there's no power, a faulty fuse should be suspected." I have the wiring diagram as well, maybe someone here can help me translate it?

Thanks everyone!

Jess
'82 CM250 Wiring Diagram.jpg
 

·
Super Moderator
Joined
·
9,852 Posts
The ignition is separate from the chassis electrical system, it is not connected to the battery. When the kill switch is in the off position or the ignition switch is in the off position either provides a connection from the CDI black/white wire to ground.

Are you checking voltages to the battery negative post or to the frame?
 

·
Registered
Joined
·
43 Posts
Discussion Starter #3
I was checking the voltages to the battery negative terminal which at the time was hooked up to the ground wire. What do you think the next trouble shooting steps should be? I’m having a hard time determining what would cause the 7A fuses to show no voltage.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
23,120 Posts
Power runs from the battery to the solenoid to the 15A fuse to the ignition switch. The ignition switch routes power to other circuits with the key turned to On or Park. The 7A fuses won't have any power supplied to them with the key Off.
I would go to the ignition switch connector and back probe the connection for
Key OFF = power on the Red wire only
Key ON = power on the Black, Brown and Brown w/White
Key P or Park = power on the Brown wire only
Key OFF there will be continuity between the Green and Black w/White which is the grounding circuit turning the CDI off.
 

·
Super Moderator
Joined
·
9,852 Posts
Check your voltages from the points Jim specifies to the frame, rather than the battery. You might have a bad ground connection at one or both ends of the battery to frame cable.
 

·
Registered
Joined
·
43 Posts
Discussion Starter #6
Okay I’ll do that today. A bad ground was one of the first things I suspected so I’ve already swapped the ground cable and connectors and cleaned up all connections with a wire brush but no dice. I’ll report back with my findings on the ignition switch this afternoon!


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
43 Posts
Discussion Starter #7
Okay, so as you expected, JT, no voltage when testing those points to the frame. No voltage from any of the fuses to the frame either. So this leads me back to the battery. Since there is no voltage to the solenoid when testing to the frame, that means it must be the battery ground, correct? I can recheck those connections I re-did yesterday unless the ground at the solenoid is what's causing the issue.
 

·
Registered
Joined
·
43 Posts
Discussion Starter #9
Check from the positive battery post to the frame. Is your frame by any chance powder coated?
Yes, the frame is powder coated but I made sure to attach the test ground connection to a bare spot underneath where the original ground cable was attached. I'm getting nothing which now leads me to believe I don't now how to use a multimeter... :LOL:
 

·
Registered
Joined
·
43 Posts
Discussion Starter #10
Okay, so I'm back to thinking its the ignition now. Tested everything with a new ground cable on the battery at the original ground point and used the starter motor as my second test ground point.

Batt+ to Frame= 12.8V
Main Fuse to Frame= 12.8V
Solenoid to Frame= 12.8V
7A Fuses to frame with Ignition ON= 0.0V

I should be seeing voltage on those fuses with the Key ON if the ignition switch was working properly right? The ignition has always been a little wonky since I got it anyway because the previous owner lost the keys and had new keys made for it.
 

·
Super Moderator
Joined
·
23,120 Posts
Yes, you should see voltage with the key on. Go to the ignition switch connector directly and back probe the harness side of the connection, if no power use the switch side. This will confirm that it's a switch problem, not a bad spade connection.
Back probe means the connector is assembled and you are testing where the wire enter the connector.
 

·
Registered
Joined
·
43 Posts
Discussion Starter #12
Results of back probing:

Key Off: 12.8V to Red Wire only.
No continuity between Green + Black/White cable at switch.

Key On: 12.8V to Red Wire, 0.0 to Black, Brown, Brown/White wires
Key Park: 12.8V to Red Wire, 0.0 to Brown Wire
 

·
Registered
Joined
·
43 Posts
Discussion Starter #13
Results of back probing:

Key Off: 12.8V to Red Wire only.
No continuity between Green + Black/White cable at switch.

Key On: 12.8V to Red Wire, 0.0 to Black, Brown, Brown/White wires
Key Park: 12.8V to Red Wire, 0.0 to Brown Wire
No Continuity between Red and Black wires with Key ON either.
 

·
Super Moderator
Joined
·
23,120 Posts
Your switch is dead. You can take it apart and try cleaning/fixing it are find a new one.
Honda is NLA, CMSNL has one for 60 Euro plus 27.50 shippling, David Silver Spares doesn't have it.
Here's the part number 35100-465-771
 

·
Registered
Joined
·
43 Posts
Discussion Starter #15
Well I'm still in disbelief, but I was able to fix it!
Normally, I would have been thrilled that a replacement was only $20 and ordered it and went about my day but since I'm stuck in quarantine with nothing else to do, I actually took it apart and was able to get it working again.

I clipped back the wires connecting to the bottom of the switch, re-soldered them (poorly, but effectively), sprayed it out with lock cleaner and put it back together making sure black/white and green had continuity on OFF and Red and Black had continuity at ON and threw it back on the bike and she came right back to life! The switch actually feels much more stable now than it did when I got it. I think when the previous owner lost his keys he did some damage.

Thanks for the help, guys. I have way more confidence diving in knowing you guys are here!
 

Attachments

·
Super Moderator
Joined
·
23,120 Posts
Good deal.
That switch looks identical to the CM/CB 400/450 series. The electrical circuitry is identical. Are the key positions Off, Run/On, Park/P? If so then the questions would be wiring arrangement in the connector, spacing of the mounting holes and height from the top of the mount.
 

·
Registered
Joined
·
43 Posts
Discussion Starter #17
Yes those are the key positions. It seems that when I took it apart, the spring loaded piece had moved out of place causing the wires not to make contact. I’m assuming it was just from years of key jiggling and vibration. It firmly clicks into place now which it didn’t really do before.


Sent from my iPhone using Tapatalk
 
1 - 17 of 17 Posts
Top