ZXR400 electrician needed!

[Lateshift]

Before this does my nut in completely :D

Mechanical stuff no problem however for me electrical stuff takes a bit of thinking about, however Jetski on Sunday had a bit of a problem on her bike in so much as the fan fails to activate and the bike will run all the way to the top of the temp guage.

So having torn the bike apart to get to all the wiring i have tried various things to fault find where the problem lies, in truth the circuit for the fan is particularly easy to work with however normal electrical principles seem to have gone out the window here because everything on the circuit checks out, apart from the only thing i cant check and that is the actually fan switch (because its positioned in the radiator).

Now cutting to the chase, i have tested the wiring (see the diagram)

1. From the battery to the junction/fuse box - ok
2. The wiring from the junction/fuse box to the fan switch - ok
3. The wiring from the fan switch to the 2 pin connector on the fan itself - ok
4. Sent 12 volts from a spare battery down the 2 wires going into the fan and it is working
5. Tested the wiring from the 2 pin connector back to the earth at the battery - ok
6. Checked the fuse and the traces in the junction/fuse box - ok
7. Cross connected the wiring to the fan switch and tested the wiring at the 2 pin connector (making a circuit) - ok
8. Crossed the wiring at the fan switch to make a circuit and turned the ignition on to send 12 volts down it - NOTHING! :D

The repair manual suggest to first bridge the wiring to the fan switch and check to see if the fan works, which it didnt, from there it then suggests checking everything i have checked (which all check out)

Totally stumped, so if anyone can see something i have missed and would like to highlight it, it would be appreciated because failing that i am just going to rig up a simple switch on the circuit to bypass the fan switch at the radiator with a permanent live so that the fan can be activated manually :)

http://www.mick753.pwp.blueyonder.co.uk/zxr400fancircuit.jpg

[DoodleBug]

Apart from cleaning the fuses mate???!!!!

Bazaar! If the wire from the battery earth to the fan checks out, then i am stumped. there appear to be a diode on the wiring diagram, have you run a wire from the batt earth to the fan and then tested the circuit?

[Lateshift]

I suppose i could bypass the exisiting earth from the fan back to the battery but that i checked that wiring by sticking one end of the multimeter in the 2 pin connector BK/Y and the other end of the multimeter onto the battery earth where the other end of the cable is and there is continuity there?

[DoodleBug]

If you did that whilst the rest of the wiring was connected, all you did was test the rest of the circuit, I think!?

edit: if the thermostat switch was bridged at the time.

[Lateshift]

if i take the fan switch out of the equation (because the circuit should work with 12 volts down it as normal anyway) and attach a switch between the 2 wires where they would normally connect to the fan switch, i can turn the circuit on and off when i am testing it (which seems to work) however if i turn the switch on and then try to turn the ignition on (knowing that all the wiring has checked out) i would expect the fan to rotate because it now has a permanent feed from the battery as it is bypassing the fan switch (which when cold wouldnt open anyway).

However this does not happen, so something in there somewhere is stopping the 12v feed actually making it to the fan, however all the wiring has continuity???

very strange :D

[SDM]

Mick.........do I take it the 'Fan Switch' is the thermostat?

[Lateshift]

Mick.........do I take it the 'Fan Switch' is the thermostat?

yes it is a thermostatic switch (basically heat sensor) :)

having done a continuity test along the wiring which checks out fine, i am unable to get a voltage reading which i find strange,

oh well off with the loom :D

[SDM]

Can the wires be taken off the fan switch and joined together?

[Lateshift]

first thing i tried that Kev, it seems to be narrowing down to a lack of 12volts to the end of the fan switch wire, i may just bypass the fuse box and wire that side of it direct from the battery, if the switch is working at least then it will operate when the engine gets hot.

if i bypass the W/BL wire by running another wire direct from the battery to the BL/W that supplies the voltage then from the other side of the switch, the fan works (which is what should happen when you join the wires).

So it would appear there is a problem in the feed from the fuse box to the switch, not a problem, just means i dont run the fan with a fuse on, hardly a drama :)

[richy rich]

might be silly but one of the wires hasn't got trapped against anything has it and shorted out? that has happened many times to me lol... just a thought

[Lateshift]

All done now, i ran a wire parallel to the exisiting 12volt feed from the fusebox, stuck a 10amp fuse inline and connected it to the fan switch.

Ran the bike up, bike now gets to half way up the temp guage and the fan cuts in :)

Happy days, and for my next trick :D :D

cheers for the input though guys, just proved to myself that sitting in the sun didnt quite make me loopy :D (but very nearly!)

[SDM]

Glad you sorted it Mick................I was racking my brain for an answer
:clap :clap :clap :clap

[richy rich]

good job you knew what to do:confused: lol

[DoodleBug]

I knew you could do it. ;)