Topic: Electrical Help (still, i have it narrowed down now)

[Ceej]

OK, my bike (74 cb750) died the other day, the first position on the ignition switch didnt work.  No headlight, no nothin.  So I got a new ignition switch, and put it in, I turned it on and it worked, started the bike, it ran for about 15 seconds and died again, same symptoms as before.

Now, I can get the electrical system to work by touching the brownwhite and red cable behind the ignition switch with the key in the first position.  Everything works like it should.  But if these two are not conencted behind the switch and everything is conencted how it should work, the bike is completely dead in frist position.  In second position, the taillight comes on, like it should.

It seems like it shoudl be the ignition switch to me, but the switch is brand new.  Does anyone have any ideas what the problem is?

Would it be bad for me to just perminately connect the brownwhite and red wires behind the ignition switch?

[HondaMan]

Red should connect to black in first position on U.S. switches. It may also connect to Brn/Wht at the same time, if it is a 3-position switch. If it is a 4-position switch, then the Red connects to Brn/Wht in the 3rd position ("Headlights" position), while still connecting Red to Blk.

Does that help?

Check the connector pins in the connector on the bike. Make sure one of them isn't broken, pushed out, corroded or has broken wire (like Blk wire). Quarter car washes EAT these switches and connectors.

[Ceej]

The connector is no longer.  Some previous owner of the bike rewired the switch up to the bars (damn them).  The switch only has 2 positions, and it is the replacement switch that the honda dealership sold me, so I imagine it is as close to original as you can get. 

Touching red to black causes nothing to happen, but touching red to brown/white causes teh headlight and indicator lights to come on as they should when the key is in first position.  The bike will not fire, however.  I have to put the key in first position and touch red to brown/white and then the motor will fire up.  Is it possible that the red and brown/white are connected to the wrong wires?  This doesnt seem to make sense, because when i connected the new ignition switch, i connected it exactly the same as the old one, and the bike used to work in this set up.

Im running out of ideas here, Im almost to the point where im just going to connect the red and brown/white for good and i guess have to disconnect the battery whenever i turn the bike off.

Any other ideas?

[oldbiker]

The big point is that your bike was running and then died! This suggests that rather than the switch being faulty, a break has occurred in a connection possibly by corrosion in one of the bullet connectors or in the connector blocks. Before you do anything drastic like making permanent connections, clean ALL connection points and lightly grease with dielectric grease. This does not require any electrical knowlege as you only deal with one connection at a time. While doing this you may come across a wire that has broken from its bullet or spade and this must be re-soldered.

IS THERE NOT A FORUM MEMBER NEARBY WHO COULD HELP THIS MEMBER OUT? i WOULD IF HE WERE ANYWHERE NEAR COVENTRY, UK.

[Bob Wessner]

Before you do anything drastic like making permanent connections, clean ALL connection points and lightly grease with dielectric grease. This does not require any electrical knowlege as you only deal with one connection at a time.

I can vouch for this as a very worthwhile couple of hours. Even if someone is not having immediate electrical problems, these bikes are all old enough to make this a good time investment to avoid problems down the road.

[CB925]

Yes I agree Oldbiker, basic troubleshooting suggests something has failed elsewhere.  Ceej, did you check all the other connections and "dialectric grease" them? 

Also, as it seem's to have died again, the actual fault may be manifesting itself in the form of burnt out contacts in your ignition switch.  At a guess this may suggest high current and as you would imagine a short, or low resistance to chasis common condition.  Have you continuity tested the igntion switch?

Have you made any headway yet?

[Ceej]

Hey guys

Ive looked at as many connections and wires that i can find.  (im sure not all, im fairly new to the sohc4 game).  I have not dialectric greased anything, but ill look into that today.  I dont have anything to test continuity with either, so im kinda just takin stabs in the dark.   

My best guess is that there is high current going into my ignition switch and burning that out.  Im not exactly sure how the inside of an ignition switch works and I cant really take mine apart.  I have been trying to trace backwards from the ignition switch but it has been rewired by a previous owner so it makes it kind of tough.  What would be causing a high current to burn out the contacts in my ignition switch? 

If there are any forum members nearby that are willilng to help out, I would greatly apreciate it.  I can provide cold brew as compensation.  Im in Norfolk, VA.

Thanks for the help guys 

[CB925]

You could try placing inline fuses in the varios circuits that split off the ignition sw.  and look for which one blows to help track it down.  That is one method if you dont have a meter.

When you "hotwire" the bike, does it work ok?  I would assume something else will go up in smoke if you left it too long.  Does the bike have any fuses at present? or has it / they been removed? If so what is it's rating?

[putnaja1]

First thing first- a meter that will test for continuity, voltage, and resistance can be had for like 10 bucks at RadioShack..  A worthy investment.
Second, always always ALWAYS suspect previous wiring jobs/"repairs"..  If the previous owner rewired the bike, check each and every one of his splices/connections.
Third, if it were me, I'd return the bike to stock, moving the ignition switch back to the stock mount and everything.  Can anyone verify whether the 2-position switch Honda gave you the right switch or not?  If not, you can order the right part, and if honda won't sell it to you (i'm almost positive they will though), a bike salvage yard and/or eBay will.  Get the schematic out of the Clymer manual, and fix the bike the right way.  Otherwise, it's just gonna give you headaches. 

The LAST thing I would do is make it permanently connected, requiring you to disconnect the battery to turn the bike off.

Jason

[CB925]

Yeah, the permanent connetion and frequent battery disconnect would suck bigtime.

Putnaja1 is right, a cheap multimeter can be invaluable.  My fluke meter (which wasnt cheap) is something I frequent break out while working on bikes and cars. 

The wiring in my K2 750 is a veritable rats nest.  I shudder every time I set eyes on it (only had the old girl a couple of weeks).  I plan to either rewire it, or buy a NOS harness.  If I rewire it I may use a small blade style fuse box and split the circuits up a bit:

e.g.   Fuse 1 - Main fuse from battery (as per original)
         Fuse 2 - Main fuse from alternator (post regulator)
         Fuse 3 - Headlight
         Fuse 4 - everything else
         And perhaps a couple of indicator lights to show if one of the supply fuses has failed (not sure where to mount these as i dont wasnt to drill holes.

While this would detract from originality, if done properly, it would be fully reversibe (generally what I aim for If I'm going to modify a classic bike ! ) and I'll snap up a NOS harness and stash it in the cupboard if one comes along at the right price.

Splitting it up like this saves losing the lot if you have a serious fault, imagine losing your headlight while scooting along at night, because a blinker or the horn shorted.  Also as i suggested earlier, the particular blown fuse will give an indication of the faults location.

As for the switch, I'm not 100% sure, but I would assume it would have the same 3 position as my K2.  I quite often see this type on ebay.

John


 

[Ceej]

When i said I had a 2 position switch, i think i may have meant 3.  There is off, posisiton 1, and position 2, so i guess that is three all together.  There are 3 fuses behind the side panel, I believe they are the main, taillight, and headlight, these are all intact.  Im now getting curious of where the wire splicing was done from the original ignition switch location.  Im not exactly sure where the original location is, but my guess is on the left side just in front of the side panel?

Perhaps where the connector was cut and rewired to the front there is a bad connection.  Can someone tell me where this connector SHOULD be located? (the one behind the ignition switch)

My brother is coming over tomorrow with a meter so hopefully that will aid in finding the problem.

[Ceej]

One more thing to add.  When i touch brown/white to red behind the switch and let the bike idle everything works fine.  I let it idle for about 2-3 minutes and all wiring/connecntions functioned/looked the same afterwards

[oldbiker]

The brown/white wire is supposed to be the tail light feed so it would appear that in the past, someone has really messed with the wiring. You say that you have no continuity tester!! A bulb and battery connected in series with some scrap wire and a probe at each end makes a perfectly good continuity tester.

[Ceej]

OK guys, I have a theory as to what has gone wrong with my electrical sysetem.  Let me know if this makes sense to you.

A couple days before I had this Electical problem i removed my front turn signals.  There where one single black wire running into each turn signal which i left unconnected, and there was a larger black ground wire bolted in with the right turn signal.  I believe that what may have happened was that when i reconnected the ground i didnt secure it good enough and it came loose.  Then I have an incomplete circuit.

I was searching through other posts on the forum and i came accross a topic where a guy had a ground that wasn't connected on one of the bolts that go into the headlight and this melted the wires to his ignition switch. 

I think that since this ground wasn't connected it fried my first ignition switch, then when i got the new one and installed it, it fried that one as well.  This would explain why it worked for about 15 seconds and then quit working.

So my questions are:
1) does this sound like a logical explanation to you guys, that this ungrounded wire could fry two ignitino switches?
2) I know i need to ground the larger black ground wire on the right turn signal, but do i need to do anything with the smaller black wires that go into the turn signals?  Or can i just leave them disconnected?


Thanks to those of you who have tried to help me out in this thread, I'm going to order another new ignition switch tomorrow and properly secure the front ground wire and cross my fingers.  Any more adivice you guys have is welcome. 

Thanks,
CJ

[TwoTired]

I think you'd better obtain a wire diagram for your bike.

Honda convention is that solid black wires without color collars are +12V switched from the ignition switch.  System ground returns to battery minus are Green colors.

If you are grounding +12V from the ignition switch, you should blow a fuse each time you turn it on.  If you are bypassing the main fuse, then it is quite probable your ignition switch as well and other bit of wiring are getting damaged.