Topic: No power, no lights, no nothing

[Lost and Confused]

I have a similar problem as a lot of our rebuilders. 1974 cb750k with new harness, new battery (13.3 volts measured ). I have a small meter. Just about everything has been replaced except starter solenoid, and ignition switch ( not OEM ). Regulator and rectifier are Oregon parts. Checked fuses four times. Running Pamco ignition, and used switched power off of regulator. When ignition turned to run I get nothing. I did a search on our forum, but did not find a good step by step post. My gut feeling is the switch.


So any help would be great. I'm not very good with electrics, although had no problems with putting in new harness. I did double check the wiring connections very thoroughly.

Bob

[brooze72]

Any lights? Maybe ignition switch itself?  Check with your meter.

[flybox1]

open your headlight bucket, take off your tank. Turn your switch on, then start wiggling every connection, one by one.  Watch for a flicker of lights. You'll find it.
Check your fuses. Check the fuse box for melted connectors or frayed and corroded wires.

[Magpie]

Check that the red wire coming off the back of the ignition switch is still soldered to it or is connected to the wiring harness. Cliff.

[aperry]

There are a lot of possibilities here.  When I installed the harness on my 750, I remember having trouble getting things to work until I noticed a medium sized green wire (with a round terminal) under my seat.  When I properly grounded that wire to the frame, everything started working.  I've noticed that particular wire has been mentioned occasionally around here and it seems like it's commonly missed.  The wiring diagram was incredibly valuable too.

[Reganator]

Maybe this will help:

http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php

That guy makes this interactive wiring diagram, if you have a simple continuity light should be easy to take a look at individual components and trace down where the issue is.  I'd select your model and start with that ignition switch.  Since the model is interactive it kinda lets you strip out complexity and focus on things as they move down the chain if you sit there and look at it for a minute.

[iron_worker]

How are you getting 13.3v out of the battery? A 100% battery should be 12.8v ... you may have measured it right after you charged it though which would give an overly high reading.

I had an issue with a brand new fuse box ... the main circuit power wire solder had broken and was not making a connection.

Get a wiring diagram and start at the battery positive and trace the power through the harness. Find out where it stops. Also check your grounds as has been mentioned. The green wire with the ring terminal that was mentioned is the main harness ground... it is essential. Make sure your grounds aren't covered with paint or corroded etc.

IW

[Lost and Confused]

Here's an update. I took my dremel tool and sanded where the negative cable goes. No change. The gas tank is off and the headlight is out. So I'm sitting looking at the starter solenoid and the short red wire from the harness is connected to the same stud as the starter. I take the red wire and put it on the stud with the positive battery cable and bang , everything works. Just one small wire. What a relief. Thanks for all the help guys.



Bob

[Magpie]

Ah, I knew it had to be a red wire!    Good find! Cliff.

[snowfighter2]

Damn those red wires!