No lights on my TC45DA

[fishpick]

My light knob does not produce lights at any settings but the switch for the lower loader headlamps works. Forgot about it until just now. Figure I'll start with a fuse but if anyone has any thoughts before I get back at it tomorrow am feel free to add your thoughts.

 

[LarryD]

After checking the fuse, look for power at the switch. At least that will tell you which direction to go, might even be the switch. I've got a cheap little automotive tester that just grounds with a clip and then just start checking connections until the light goes out.

 

[jinman]

If you have instrument panel lights, check fuse #7. At least that's the one for the headlights on my older TC45D with the rocker-style headlight switch.

 

[wrenchguy]

If you don't find a blown fuse,pull the switch out of the upper console. The power wire for the rotary switch is the orange wire. If its disconnected from the switch,connect the wire to the "30" terminal on the switch.

 

[raeuber]

I had the same problem on my TC55DA. I disconnected the wiring connector from the switch to do some testing. I couldn't find anything wrong so I plugged the switch back in and go figure, the lights work. My best guess is that the connections must have gotten dirty or corroded and the unplugging and re-plugging cleaned them up. So look for that also.

 

[fishpick]

Well, I just got to this and left the barn scratching my head.
#7 fuse was fine... #4 was blown. Replace that.
The rocker switch still produces the lower lights. The AUX rear has juice for a work light but the rotary switch for the main lights still produces nothing.
I pulled the side panel off and took out the switch. I tested the orange wire to the blue wires and it's putting 12V across them... When I put a jumper from orange to a blue wire I get no lights... I tested all 3 contact settings on the switch and they are all good (which is irrelevant when I jump the switch and still get no lights).
I looked at the dual filament bulbs and they look fine.
What else could it be?

For the record there's too many wires on this thing! It's a tractor not a space ship... At any rate, I need Scotty I guess cause I'm mostly out of ideas... Is there some other relay AFTER the switch I now need to look at?

 

[wrenchguy]

Is there some other relay AFTER the switch I now need to look at?

I can't remember for certain but I do believe the headlights power goes from the rotary switch through a relay. Sorry,don't remember which relay it is if it does.

 

[jinman]

Fishpick, I think you may have the clue you need. Fuse #4 supplies coil power to the headlight relay through the light switch. When the relay energizes, its contacts route power from fuse #7 to the headlamps. My guess is that the headlight relay (K8 on my old TC diagram) is the culprit. I'm including a diagram of the relays. There were some changes with the NASO flasher module, but your relays are probably the same or similar. It should be the one beside or near to your glowplug timer relay. It's item 8 in this diagram, but yours will look slightly different.

 

[fishpick]

Wouldn't it be nice if that was it jinman...

I was out in the barn with the snow blowing in on me working this so I can report where I'm stuck.
In the back of my manual there's a bunch of wiring schematics I had forgotten about. According to the manual relay #9 is the front lamp relay... Now, let me say the manual is already suspect because it also says really #3 is the glow plug lamp but there's nothing there and I know from a past repair the lamp is tied to the timer relay... But I digress... It also said the hazards are relay #4... So with the hazards on I yanked what I thought number 4 would be and out went the blinkers...
Took that relay and used it as known good and with the work lights (rocker switch) lights on and the main lights on moved the known good relay around the panel.
Nothing. Work lights died when I pulled relay 5 and came back on when I added the known good relay from #4... Then the drumroll on #9 - front lamp relay. No lights, replaced with the known good relay and still no lights. Turned the knob switch to make sure it was live. Grrrrr, darkness...

I also confirmed the issue is not the connection under the hood as testing on the plug side is 0V so I penetrated a wire on the dead side upstream from the switch and there's no voltage there too...

So, I am kinda not sure what to do next. Wiring harness mess is in great shape, no rubbing wear, no critter nesting. Everything else is cool on the tractor. Maybe I give up on ever having lights again...

One thing that's also depressing about the manual schematics... The wire numbers only match up about half the time to what's really wired up and working.

Nutshell summary:
Rotary switch tested out.
Rotary harness tested. When jumped lights still do not come on.
Relay 1-9 tested and checked out.
All fuses are good.

Power to switch - no power under hood. Work lights, flashers, aux light in rear all are shining bright. (I am suddenly missing my old 8N)

HELP!

(was just rebooking at the diagram jinman... Yes thats different, I have a block with 9 (minus the one in slot 3) and then the 3 below, like your where it labels the headlight one... Those 2 down below are a different type. I also had switched those two to test for a bad one there since the manual schematic isn't a diagram telling me what #9 relay looks like)

 

[RobertN]

Maybe a broken wire, or, I hate to bring up, mice getting in to the wiring?

My MIL drives her car at least every other day, often more frequently. It is parked in a pretty tidy garage. Sure enough, mice/rats got in the engine compartment and did a job on the wiring. Had to be towed to the Buick dealer... They had to replace multiple wire harnesses, and car was gone for over a week.

Oh... just saw you checked for rodent damage...

Only way is to start from where there is 0V and keep working your way back to the switch... Hard to do debug with snow blowing in; move to garage maybe?