Author Topic: CB750 Ignition Switch Connector (Read 9269 times)

nwrocker · « **on:** February 15, 2012, 09:40:51 PM »

I hope I can get a little help here. I am re-building a 1974 CB750K. The existing wiring harness is missing the connector plug to the ignition switch. I have found a new connector, but I could use some help to position the wires. I have two brown wires, a brown with a white stripe, a red and a black wire.

Looking at the ignition switch the pins look like:

PIN ___ PIN
PIN PIN PIN
CLIP

I appreciate the help guys

cookindaddy · « **Reply #1 on:** February 16, 2012, 02:56:37 AM »

I have a 78 so I won't try to help you since mine might be different.

The advice I wanted to offer is that with the schematic diagram (which shows the colors) and an ohmmeter, you could check which pin is which on your switch and make sure that you have the right wires going to the right pins.

I guess what I am saying is that your bike has had the connector cut off and you don't know what if any other "modifications" have been done by previous owners so it may be best to check what you actually have rather than just matching up colors. Might be less smoke that way?

nwrocker · « **Reply #2 on:** February 16, 2012, 07:59:07 AM »

Thanks... I have restored the wiring on the rest of the bike.

I am still hoping someone can identify the wiring pattern for the ignition switch.

Thanks

fingersofskill · « **Reply #3 on:** February 16, 2012, 09:10:21 PM »

I have a 74 750.. you have the shop manual, does it not have wiring diagrams that show what you need?
Manuals are here if needed: http://forums.sohc4.net/index.php?topic=17788.0
if what you seek is not listed in any of the many docs there on that thread, I will gladly check mine out for ya and document.

Dave

Johnie · « **Reply #4 on:** February 17, 2012, 05:59:55 AM »

I have a 74 CB750 and the spot the ignition switch plugs into the harness is a 4 plug connector. Below is a pic of the harness end and switch end. I am not sure why you would have a 5 lead connector there?

MoMo · « **Reply #5 on:** February 17, 2012, 06:28:26 AM »

Johnie, the 5 plug is for the (newer

) models, 75 and up.

nwrocker, do you have the connector on the harness? ...Larry

bollingball · « **Reply #6 on:** February 17, 2012, 06:36:01 AM »

Good point Larry
Johnie If you have that connector on the harness this will be easy. So tell us if you do.

Ken

Johnie · « **Reply #7 on:** February 17, 2012, 07:20:35 AM »

OK, so rocker has a 75 titled as a 74 with the different connector than my K4. Got it...

nwrocker · « **Reply #8 on:** February 17, 2012, 08:40:57 AM »

I appreciate it guys. It is a 74 but it has the five wires in a 6-pin plug.. The ignition switch is on the upper triple tree and not on the frame under the gas tank. Unfortunately there is no connector on the end of the harness here. Each of the wires has the cheap fast crimp wire ends crimped on them. Here is a picture. In this picture you can see that I have pulled the ignition and it is just sitting on the engine so I can work on it.

I do have a new connector coming. I have the wires plugged in but I haven't tried them out as i was hoping I could get some help from you all before I turned it on. If anyone had a picture of the back of the ignition plug that would give me the info that I need to set the pins. Thanks

nwrocker · « **Reply #9 on:** February 17, 2012, 08:52:46 AM »

Quote

Manuals are here if needed: http://forums.sohc4.net/index.php?topic=17788.0

Thanks. I have looked there and I found the wiring diagram for the harness, but not for the connectors. I heard that the Haynes manual may have a diagram of the connectors but I don't have access to that manual.

hondalna · « **Reply #10 on:** February 17, 2012, 10:10:27 AM »

You might want to try this guy. He has diagrams for everything. plus he has the plugs and wiring ends for everything. plus he sell things very reasonable. Good luck Sales@OregonMotorcycleParts.com

hondalna · « **Reply #11 on:** February 17, 2012, 10:22:59 AM »

plus (I should have tol you he makes electronic parts for our old bikes as well) He will even tell you how to rewire things, look at his diagrams on his web pages free .

lucky · « **Reply #12 on:** February 17, 2012, 10:35:53 AM »

I am going to give you the answer but you really need to buy a Clymer's workshop manual. Then you could easily look this up.

You have the wrong ignition switch.
You have a 1977 F model ignition switch.

It had a PA (parking/accessory ) function for when the ignition switch is off.
It is much more complex in its internal set up.
Those two brown wires were actually two ORANGE wires.

PIN ___ PIN
PIN PIN PIN
CLIP

K1's-K7's BTW are all the same. ALL of those ignition switches have FOUR wires.

Black IG All black wires- all feeding 12V
Brown/W TL1 (headlight switch)
Red BAT (main fuse)
Orange TL2 (tail light fuse)

The brown /w wire goes to a multi connector in the front of the bike that goes to several things in the front lighting . Speedo lights,turn signals, etc.,.

TheCB750 is a VERY SIMPLE SYSTEM.
Only 3 fuses!! Tail lights- head lights -and main fuse.
I wish ALL bikes and cars could be this simple.

If I was you I would just get a K model switch and plug and play.

TwoTired · « **Reply #13 on:** February 17, 2012, 10:48:09 AM »

The switch model you are using wasn't introduced to US markets until 1975 (F models). Could have been bought as Early as September 1974 with new model introduction.
I have a spare wire harness from a 77 CB550K that used the same switch and has standard Honda color code wires. I noted the wire colors in the harness to correspond to your switch plug below in blue. Honda was smart in putting the red power supply wire in a center position. So even if you wire the outer pins wrong it shouldn't hurt anything, it just won't work right, allowing a later swap to correct function. (I haven't tested this, though.) I should note though, that your wiring may be custom and not follow Honda convention. I say this because the two browns are normally connected together in the harness. You could check continuity between them to verify that hasn't been modified.

Quote from: nwrocker on February 15, 2012, 09:40:51 PM

I hope I can get a little help here. I am re-building a 1974 CB750K. The existing wiring harness is missing the connector plug to the ignition switch. I have found a new connector, but I could use some help to position the wires. I have two brown wires, a brown with a white stripe, a red and a black wire.

Looking at the ignition switch the pins look like:

Brn Br/wht
PIN ___ PIN
PIN PIN PIN
CLIP
BLK Red BRN

cookindaddy · « **Reply #14 on:** February 17, 2012, 12:55:21 PM »

The same switch with the park/acc position and the five pins is on the 750 K7 and K8

nwrocker · « **Reply #15 on:** February 17, 2012, 02:34:51 PM »

Thanks for the info. My motorcycle battery is now dead so I will have to charge it up and try out the wiring pattern.

The conversation about it being a F model is mystifying. The title says it is a 1974 with a vin 2337774 making it a K4. The ignition, gauges and upper triple tree all fit together.

TwoTired · « **Reply #16 on:** February 17, 2012, 03:45:35 PM »

Does your switch have the lock bolt for the forks and do your forks have the slot to accept the locking bolt?

nwrocker · « **Reply #17 on:** February 18, 2012, 12:20:09 AM »

The unit bolts to the triple tree and the locking bolt would hit a weld on the front frame tube to keep the forks from turning.

TwoTired · « **Reply #18 on:** February 18, 2012, 09:01:58 AM »

It's hard to believe a 74 K model would have that feature.

Curious. Does the VIN tag number match the number stamped into the frame's headstock on the opposite side?

Hope you get the wiring sorted.

Cheers,

Patrick · « **Reply #19 on:** February 18, 2012, 11:10:22 AM »

I am not sure how helpful this will be, but I will offer it anyway.

The Red wire in the power to the switch from the batter.

The black wire is the power to the rest of the bike.

The br/w wire runs the lighting on the bike (except tailight) and connects to the black wire in the headlight bucket. It then goes back to the swqitch where it also powers the br wire. It is NOT powered by the switch.

The br wire runs the taillight. It runs only from the switch. The switch connects r to b. The parking feature (second notch on the switch) connects the red to br only.

Patrick

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Author Topic: CB750 Ignition Switch Connector (Read 9269 times)

bollingball