L48 dead combination switch circuit

[littlepony]

None of the accessories controlled by the combination switch (head light, horn, tail light, turn signals) on my older L48 will come on. There is 12V power to two wires on the (new) switch when the switch is OFF, but when I turn it ON, the power disappears! Any suggestions for further evaluation? thanks

 

[PoTreeBoy]

How many wires are on the switch? Are you testing with a multimeter or a test light? I think your meter may be giving you false results. Does the tractor start?

 

[littlepony]

8 wires to and from the switch. I am testing with a multimeter and testing at connector just below the switch. You can see rotary switch and connector in pic below. Power clearly goes from ~12V to 0V when the rotary light switch is turned from OFF to ON.

 

[Bee-Positive]

Could be a bad ground or broken wire (mice?) resulting in an open circuit when the switch is turn on. I didn't find a WSM on Kubota Books or anywhere else that was free so I didn't have an electrical diagram to look at. It would be in your best interest to get a WSM with diagram to trace the wiring.

EDIT: Assumed you checked all the fuses.

 

[PoTreeBoy]

8 wires to and from the switch. I am testing with a multimeter and testing at connector just below the switch. You can see rotary switch and connector in pic below. Power clearly goes from ~12V to 0V when the rotary light switch is turned from OFF to ON.
View attachment 178087

Sorry, I had a momentary brain outage - was thinking keyswitch. Like B+ said, a schematic would be helpful. My L35 is probably very similar, but this is the one area where my WSM doesn't match my reality - apparently the older L35's didn't have turn signals so the switch in the schematic only has 6 wires but mine has 8, if I recall.

Unless Kubota has changed things since 2004ish, the lights turn off with the keyswitch, unlike a car. The keyswitch feeds the comb switch. The only lights that operate with the key off are the hazard flashers, which are separate, I think. So I'm surprised you have 12v at the comb switch unless the ignition switch is on. This is one time that a test light would be better. The sensitivity of the multimeter will show power even when it may be just leakage through a poor connection.

So, as B+ has already said, check for dirty connections, using a test light (with a bulb, not an LED). Could be a loose fuse.

 

[North Idaho Wolfman]

None of the accessories controlled by the combination switch (head light, horn, tail light, turn signals) on my older L48 will come on. There is 12V power to two wires on the (new) switch when the switch is OFF, but when I turn it ON, the power disappears! Any suggestions for further evaluation? thanks

Where did you get the new switch?

 

[littlepony]

Sorry, I had a momentary brain outage - was thinking keyswitch. Like B+ said, a schematic would be helpful. My L35 is probably very similar, but this is the one area where my WSM doesn't match my reality - apparently the older L35's didn't have turn signals so the switch in the schematic only has 6 wires but mine has 8, if I recall.

Unless Kubota has changed things since 2004ish, the lights turn off with the keyswitch, unlike a car. The keyswitch feeds the comb switch. The only lights that operate with the key off are the hazard flashers, which are separate, I think. So I'm surprised you have 12v at the comb switch unless the ignition switch is on. This is one time that a test light would be better. The sensitivity of the multimeter will show power even when it may be just leakage through a poor connection.

So, as B+ has already said, check for dirty connections, using a test light (with a bulb, not an LED). Could be a loose fuse.

 

[littlepony]

Thank you both. I will get a WSM and get down and dirty.