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What is this ground connection for?

1380 Views 18 Replies 4 Participants Last post by  gavinbpugh
I'm wiring up my CM400E, and I stumbled across a ground female connection (there are actually two female terminals inside) stemming immediately from the headlamp female plug, and I cannot seem to figure out where it connects to. Looking at the wiring diagram doesn't seem to reveal anything either. Any thoughts?

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Likely just a connector that's common to that harness but not used on your model. If you don't have any corresponding male connectors on green wires laying around, and everything works, just ignore it.
Good to know—thanks jt.

On another note, I'm still trying to determine why my starter isn't working. When I press the switch, all of the dash, turn signal, head lights dim, but the starter motor won't crank. I can only start the bike when I use jumper cables from the battery straight to the starter motor with the start switch pressed. Is this a solenoid issue?

Also, I think the PO tried to do some funky wiring in two places. In the headlight bucket, a few of the green ground wires, as well as some of the black wires (also ground???) were clamped together with what looked like small bits of brass wrapped in tape. Would this be the reason for some of my electrical issues?

I'm at work. I can post pictures when I get back to the bike this evening.
Had that problem on an '80 CM400A I just picked up. Means that the starter solenoid is drawing current but not engaging. A sharp rap on the solenoid with the but end of a screwdriver freed the thing up.
You also need a better set of schematics than that. PM sent.
Green is Ground. Black is switched power from the ignition switch. If there's Black and Green connected then the Black wires were added by the PO since the harness hasn't melted down when the key was turned on. Need to removed the tape on the harness and figure out what the PO was trying to do
Pressing the start button should remove power from the headlight (it should go out completely) and diverts that power to energize the solenoid. Sounds like your start button may need cleaning/replacing.
Here are the photos I promised. The solitary green ground is coming from the red plug, which comes from the right-hand controls, including the starter switch. Is this a proper wiring job as part of the original harness?

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According to the schematics, these are electrically correct. The schematic does show a mechanical splice for the black wires coming off the red plug. The print also shows two green coming from the plug. Doesn't show a splice, but electrically correct. The splices aren't kludges so more than likely correct.
One of the green conductors should go to the starter switch and the other to the headlight via a connector. One of the Black conductors should go to the starter switch and the other to the front brake light switch.
Okay, I've removed the starter switch and thoroughly cleaned both surfaces, as well as rinsed them with electrical cleaning fluid. I'm still not getting anything.

Are there any resistances I should check for?
Check continuity on the solenoid where the red/yellow wire and the green/red wire are connected.
Should be very low resistance.
Still think the solenoid is stuck.
If you can connect directly to the starter motor and get it to go, then it means the solenoid isn't engaging.
The splices in the picture are original Honda.
There's a second small wire coming off the solenoid, Green w/Red. That is the ground circuit for the solenoid and is connected to the neutral safety switch and clutch safety switch. You can check that there is ground by using one VOM lead to the positive battery terminal and the other to that wire connector. You should see ground/voltage reading when the transmission is in neutral or if in gear when the clutch lever is pulled. There is a "rectifier" in the circuit to prevent voltage feedback because of the 2 different type circuits. If that diode is missing the starter won't work in neutral.
Hey Jim, I bounce between 12-13V when testing the positive battery terminal to that green/red connector.

I followed this thread and found that everything read normal except with the starter switch. My starter switch reads about 1 million ohms in all positions: ignition switch on in run position, ignition switch on in off position, ignition switch of in any position.

If I'm getting these readings, and can start the bike using jumper cables, then does that mean something is going wrong with the starter switch or the solenoid?
Your ground readings are fine.
With the trans in neutral, use a jumper wire from the positive battery terminal to the Yellow w/Red wire connector by the solenoid. If the starter works the solenoid is good. Now use the same jumper to the Yellow w/Red wire in the connector at the headlight. Starter works? If so then connect the jumper wire to the solid Black wire in that same connector and try the switch. Starter works? If so the use your VOM to check for voltage on the Black wire with the key in the ON position. If the starter doesn't work on this last test then the switch is bad
Great. I'll give that a shot tomorrow.
Let me know if I did this right: I connected the jumper cable, both positive and negative leads, to the battery, and I grounded the other negative lead to the bike, and connected the other positive lead to the disconnected red and yellow wire at the solenoid. If I did this right, I got nothing, and the solenoid is toast. If I did this wrong, please let me know!

Also, based on my test for the start switch, mentioned above, the switch is bad, right? I should be reading 0 ohms when the switch is off or the ignition is off. I'm reading virtually infinite ohms in all positions (about 1 million-1.2 million).

Also, non-electrical related issue regarding leaks posted over here. Thanks for the help!
Something a bit kerflukey here. Originally you said that when you pressed the starter button, the lights dimmed and the starter motor did nothing. This indicates a heavy current draw (the solenoid coil). Nothing happened re: starter motor. Indicates that the solenoid did not engage providing high current to the starter motor. If your starter switch contacts measure > 1 megohm, there is no way the lights would have dimmed. Also, it indicates that the grounds could not have been interrupted.

Why do you now think that the solenoid is toast? Did it heat up? Did you hear the armature move?

The solenoid doesn't care what the polarity is. Nor would I have connected it directly to a battery for any length of time. It is designed for short powered intervals.

If you did not experience excessive heating, then the armature is more than likely stuck.
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Okay, pardon my ignorance here:

The armature doesn't move at all (by that, I mean I don't hear anything click). In taking apart the solenoid, the hot wire coming from the positive battery terminal accidentally made contact with the opposite solenoid bolt and the motor started cranking, which is the first time that has happened without jumper cables connected straight to the starter motor. I assume this was me accidentally hot wiring the bike.

In disassembling the solenoid, I found that little copper rectangular plate, along with one of the copper bolt contacts, was covered in crud. I scrubbed them down well and rinsed them in electrical cleaning fluid. Reassembled and still no click from the armature and no cranking bike. I can't overemphasize how neglected this bike was, so it would not surprise me at all of the inner coil of the solenoid is completely corroded and full of crud. Considering a replacement solenoid is quite inexpensive, I think I've found my problem considering the symptoms of my non-cranking bike. Thoughts?
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You're probably right. If your suspicions are correct, then measure the resistance between the coil terminations. It should be open.
When you shorted the bolts, you did what the solenoid was supposed to do.
The good news is that the starter motor works!
Suspicions were correct! $10 later and a brand new solenoid makes her fire right up! I've got a street ready bike, folks. Now I f I could just do something about those oil leaks...
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