Tail light fuse blowing on ignition and burned ignition switch plug

Hey guys,

New forum user here, and new KZ440 rider.  My bike is almost road-ready, but it keeps blowing the tail light fuse every time I turn the ignition to "on".  There is also discoloration in the ignition switch plug, as pictured, that looks like heat to me.  

I've already gone through every plug I could find from front to back with Deoxit.  Some more than once.  When I resistant-test the ignition switch plug, per the manual, it reads fine.  The plug wires and pins also visually look fine to me (also, I broke that corner with pliers trying to get it loose).

I am thinking about cutting the ignition switch plug completely out (bypassing) and just hard-wiring it temporarily to see if it blows another fuse.  Anybody have any reasons why that might be a bad idea, or any better suggestions?  If I pull the ignition switch out, can I break it apart to check the wiring on the inside and look there for a potentially shorted wire?  I haven't been able to locate any sketchy wires yet between the ignition plug and the tail light.

Much appreciated.

 

Welcome from the UK, I would suggest you read and work through the section on "short circuit" faults in the guide on the below link

www.kzrider.com/forum/forum-index/faq-wi...-fault-finding-guide

unplug the items in the green circles.

Put your meter on continuity.

place one probe on the blue/red wire in the fuse holder.

other probe on the battery's ground terminal

Is your meter beeping?
What is the resistance?

That is amazing, guys.  Thanks so much.  It will be a little while before I can do the full resistance testing.  When I unplug the tail light, and do the voltage test on the output side of the blown fuse, I am reading full voltage.  The power feed on that fuse comes from the ignition switch and goes out to the handlebar start/stop switch.  So, is my short-to-ground going to be somewhere in that wire between the fuse output and the start/stop switch on the handlebar, or could it still be in the main ignition switch somewhere?  Just FYI, my main fuse was also blown this morning.

Ok F64, I unplugged the connectors that you suggested and did the resistance test.  I get a reading fluctuating between .3 and .4.  Does that mean anything significant?

 

I forgot to mention--you don't want a fuse in the fuse holder for that tail light circuit.
I may have also grabbed the wrong schematic.
I was looking at a 1981 kz440d2
Your schematic is actually simpler.

If there was no fuse in the holder and you had your probe on the red/blue wire,
Then the short should be in the red/blue wire in the section from the fuse holder to the ignition switch connector(4 wires-white,red,brown,red/blue).
It's the highlighted green path in the 3rd image below.

You can leave the probes on the negative terminal and the red/blue wire at the fuse holder and move the wiring harness to see if the meter resistance reading changes from 0.3 to OL or open(which is what you want).



Also, look for tight bends, pinch points or burn holes in the wiring harness from the fuse box to the ignition switch connector.
Check where the wire bundles go into the headlight bucket.

So, here's a point of high strangeness.  I couldn't get any change in continuity readings by wiggling the length of the wiring harness.  Ends of wires and plugs also looked good.  So I decided to unwrap the harness, and found this splice in the middle of the red/blue wire under the tank.  This is not in my schematic at all.  Here's what I know:

1) One brown/white wire feeds into the left front turn signal and splits to the speedo.
2) Other brown/white wire feeds into the tachometer plug.
3) Tach plug has heat discoloration at the brown/white wire.
4) Blue wire at the splice feeds into the right front turn signal.
5) Someone installed aftermarket front turn signals at some point.
6) When I unplug the bullet connectors just south of the turn signals, I get open lead reading in the red/blue wire.

So...it seems to me that whoever installed the front turn signals also did the splice, and when the ignition switch is turned on, that circuit is getting power from both ends and causing excess voltage/heat, thus blowing the turn signal fuse at the end of the red/blue wire.Unless someone foresees a major explosion or catastrophic meltdown, I'm planning to cut out that splice in the red/blue wire, return the turn signal circuit to factory schematic, and see what happens.  I may have some gremlins in my instrument clusters to track down, but at least I'll hopefully be starting with more knowns than unknowns.Any insights or confirmations appreciated. 

Believe it not, the schematic may be wrong.
I had to look at prior years to see where the brown/white wire connects to.
On your schematic that wire doesn't attach to anything.
On prior years the brown/white attaches to the red/blue.

That may be a factory splice that you took a picture of.

Which bullet connector did you disconnect that gave you an open reading?
That may be pointing to your issue.

If you look at the schematics below, you will see where the brown/white wire connected in the past( green square)---to the red/blue wire.
Now look at the last schematic.. That is yours..The brown/white(brown looks like dark red---the thick grey line is next to the wire) wire does not to connect to power at all.
It just connects the lights together without any connection to power.



 

It had the look of a factory splice, wrapped neatly in blue tape, but I couldn't find that exact splice on any of the schematics.  My bike definitely follows the schematic of the D4, except for that anomaly.  I got open lead when I unplugged the bullet connectors just before the front turn signals in the headlight pod. If I just unplug one or the other, reading goes to about .6.

Yeah, Kawasaki messed up that part of the schematic.


Your turn signals may be wired up wrong.

How are they wired up?
Are your aftermarket turn signals 3 wire?
My guess is that blue wire going to the turn signals is connected to ground. Which is bad.
You can check the continuity between all the turn signal wires and battery ground with the bullet connectors disconnected.

more specifically,
meter on continuity

disconnect both bullet connectors to turn signals
one probe on battery negative.
other probe on the bullet connector going to the right turn signal
what is the reading

measure the left turn signal bullet connector
what is the reading

If the readings are not Open or OL, trace that wire to that turn signal to see how it is connected.
 

Problem Solved!!

So, I studied and studied the schematic, and metered and metered and metered.  Almost everything on my bike follows the schematic of the 1982 440-D4 USA model, except that goofy splice where the front turn signals, tach and speedo lamps are hard wired into the red/blue tail light circuit.  So, it seems to me like they are getting voltage from the tail light circuit when the ignition switch is engaged, and they are getting voltage from the other side from the turn signal relay when the turn signals are engaged at the left handlebar switch.

In any case, I decided to go with my gut and break that splice apart in the tail light circuit to see what happens (I can always solder it back if something blows up).  I spliced the two brown/white wires and the blue wire back together, left the red/blue tail light wire running solid, and presto....problem solved.  I now have tail light, and functional turn signals.  And my bike matches the schematic I was following now.

Thanks again, guys, for all of your input.  I still have no idea how this issue happened.  I'm thinking maybe I have the European model, and whoever wired the front turn signals followed the US schematic and created a double circuit or something.  Either way, I'm glad to have it fixed.

P.S.  My bike also has the yellow/red wire on the starter solenoid connecting to the ground circuit, like the A2/D2 schematic, but the everything else seems to follow the A3/D4 pattern, other than the turn signals being spliced into red/blue tail light wire.  And my front turn signals are two wire, just like in the A3/D4 schematic.

Many Thanks again for helping me crack this case.

 

Good job!
One thing you may want to check..See if your gauge lights for the speedometer and the tachometer are working.