Brain freeze from schematics

[Jefe]

Hello,

I've been trolling in the background and gotten some great tips but I don't find anything in the archives on my problem.

Replacing the headlight relay on my 79SF, I shrewdly hooked it up wrong and zapped it into near death by funneling a jolt of AC from the alternator into the DC system.

I turn the key now and get no lights or action from the starter; it seems clear I fried something.
I checked the kill switch for continuity and it works as it should - none when it's on "kill" and continuity when it's on "on"
I opened the ignition switch and found no sign of fire damage.
I checked voltage at fuse box with key turned on and got 12 volts between all the fuse wires and the engine block.
And then my brain turns to oatmeal as the circuits branch and send wires into various modules

Any suggestions for how to approach my problem? Any suggested links that will explain reading and using a schematic? I've read some simple "how-to" articles and they seem straightforward, but I get muddled in all the forking around I see in the XS11 schematic.

Thanks for any tips,

Jeff

[jetmechmarty]

Start by finding the blown fuse. Check them first.

[natemoen]

I agree that it is probably a fuse. I did something similar and freaked out thinking I blew my tci....then I checked the fuses.

[CRXSi90]

Just a note:

I believe there are five fuses:
-four under the right cover (smaller current ratings)
-one under the left cover (main fuse, higher current rating)

Needless to say, you should check all five. I believe the main fuse is encapsulated in some rubber housing. Forgive me if my memory fails me; it has been 4-5 years since I started my XS project, then life happened.

[Jefe]

time for topcats new box

Thanks for the suggestions. I did check continuity on all fuses and they came up good, but maybe pressing them with the probes changed things. Is there some other fuse that isn't on that phenolic plate looking at you?

I've held off installing a topcat fusebox on hand, since I didn't want to throw more worms into the can. Maybe I'll do that anyway, though, just to eliminate flaky fuses as an issue.

Jeff

[crazy steve]

Jeff, the '78-79 diagrams are the worst of the lot... with more than a few mistakes.

First, the AC that comes to the relay is low potential; about 7 volts, so I seriously doubt if that did any harm. More likely you cross-connected and blew a fuse, so check those first...

And don't assume the fuse is good if you're seeing power on one side or the other; pull it and check for continuity.

[crazy steve]

Ok, while I was typing, I see you've checked the fuses...

Next, check for power at:

Red wire at the headlight relay.

Red/white wire at the starter solenoid.

Red/white wire at the TCI.

If you have power at all these places, try jumpering the solenoid; touch the blue/white wire to ground. If the motor turns, your start button circuit is the problem. If it still doesn't turn, you may have a bad solenoid.

You should also check/clean your main ground connections; battery to frame, motor to frame.

[Jefe]

ah, those assumptions ...

I just learned something new about fuses - there's a kind that lights a little light when it blows, which means testing continuity is NOT the way to check that bad boy.

So, yes, it was a fuse and the zapped bike will ride again soon.

I'll check my KZ305 hulk and hope it has the same problem.

Thanks!
Jeff

[b.walker5]

ah, those assumptions ...

I just learned something new about fuses - there's a kind that lights a little light when it blows, which means testing continuity is NOT the way to check that bad boy.

Thats correct Jeff, but unless you have them fitted into a TC fuse block them you're not going to have that problem on your bike, and, as the light only glows when the fuse is blown theres very little need to be testing the continuity, the visual clue is right there in front of you.