Topic: '78 CB400F fuses

[scotto75]

Hi everyone,

I've got a problem with the electrics on my later model 400F. I've had an intermittent power issue which I traced to a broken fuse (not blown but just snapped). I thought that solved the issue but I returned to the bike yesterday after a fortnight away, turned the key and the warning lamps came on, but after two little blasts on the starter the electrics went completely dead, with no warning lights. I didn't have a meter with me so have been unable to test what is or isn't getting a voltage, but the plan is to start at the battery and work my way to the ignition switch.

My question is regarding the fuse box. I have both Haynes and Clymer manuals but the circuit diagrams in both only show one fuse, the main one connected to the red wire from the battery. I have found another circuit diagram online which shows three fuses, main + headlight + taillight, but my bike has five fuses.

My question is what are the two additional fuses for, or where can I find a diagram that includes the five fuses or fuse box in the correct circuits?

Thanks!

[robvangulik]

Top and bottom are SP(ares)

[scotto75]

Ahh. That makes a load of sense. Mine's without the labelling. Thanks!!

[scotto75]

Just to add that I've now sorted the issue. Used the multimeter and pulled off the ignition switch connector block. Found 12.5v at the battery, both sides of the main fuse and at the female spade connector connected to the red wire in the ignition switch block. Used the meter to do a continuity test on the black and red spade connector at the ignition switch and found the switch opened and closed the circuit as it should when the key was turned, so the issue was with dodgy connections in the connector block and not the switch. I used a tiny flat blade screwdriver to close the gap on the female spade connectors in the plastic connector block, cleaned all of them up and reconnected. Job done. No for a ride whilst the suns still shining!

I know no ones probably that interested but someone may stumble across this with a similar issue and it may be of help so thought I'd post it up anyway.

[robvangulik]

Well done, everybody should post results, makes fora like this more valuable!