Author Topic: CB750 K5 Wiring Issue  (Read 545 times)

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Offline JLeather

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CB750 K5 Wiring Issue
« on: November 07, 2022, 06:08:42 AM »
Running out of patience chasing a wiring issue on a K5.  Maybe someone has a new idea or a way to run this down.  I bought the bike as a non-runner and one of the handlebar controls was busted up.  I picked up a new matching set of stock replacement controls from 4into1 and wired the bike up.  Also, although it's a K5 I had a better set of K2 fork ears and signals so I wired them up so the signals do not have or use the park/running lights just the flashing lights. When I first got the bike together everything worked fine including all the indicator lights, the turn signals on both sides, etc.  On the maiden voyage I signaled for a right turn and the main fuse immediately blew (luckily I had a spare with me). Limped it home and started checking.  First I put another fuse in and tried the left signal; popped it immediately. Then I unhooked all 4 signals and tried again; fuse didn't blow.  Hooked the signals back up 1 at a time trying the signal switch after each one and the fuse never blew again (annoying) but after I got all 4 plugged back in they also didn't flash anymore.  I figured maybe the flasher had quit so I got a new one and changed it, still no flash.  So now when I signal left or right both signals on that side and the indicator light up, but it doesn't flash.  And I still never found any reason the signals would have been blowing my fuses. Anyone got an idea?

Offline bryanj

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Re: CB750 K5 Wiring Issue
« Reply #1 on: November 07, 2022, 11:29:15 AM »
Typical faults of a flasher can, battery needs to be well charged or engine running for flashers to work
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline newday777

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Re: CB750 K5 Wiring Issue
« Reply #2 on: November 07, 2022, 11:48:33 AM »
On the K5-K6 there is a jumper with brown/white that has a small black sleeve on one end that goes in the black lead and the br/wh on the other. Did you get that plugged in when you rewired it.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline JLeather

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Re: CB750 K5 Wiring Issue
« Reply #3 on: November 13, 2022, 07:47:48 PM »
Thank you all for the suggestions. There was actually a combination of mistakes, however the jumper was indeed one of them.  Oddly the Honda shop manual only shows that jumper for K6 and I have a K5, but I did need to add one.  I had all the lights and the ignition solely on the 15A fuse. The main cause of my fuse blowing, however, seems to have been the turn signal buzzer wire which I eliminated but had plugged into a ground by mistake.

Offline newday777

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Re: CB750 K5 Wiring Issue
« Reply #4 on: November 14, 2022, 12:48:50 AM »
Thanks for the update. Glad you found it and got it working correctly.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A