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Can’t find fuse for lights

#1

D

Danpoet

Yardman 13AT604G755 I haven’t been able to locate the fuse for the lights. I did find the 20 amp starter fuse behind the dash panel. The manual (770-10448d) says “the other fuse is mounted to the inside of the frame, behind the battery”.
I pulled the battery, and the only thing that I found mounted to the frame, was the starter solenoid. I removed it to double check for a fuse, but found none. I checked for 12v with my meter grounded to the frame, and couldn’t find 12V on the switch assembly harness at all. The mower does start and run, however.
I removed the switch, and ohms checked the L to A2 position on the switch. It read 0 ohms. The B to A1 switch position is 0 ohms in the start (spring loaded) position. The schematic shows a 20 amp fuse for the lighting on the ground side (green wire) of the lights.
I can’t find this fuse anywhere.
The light switch connector is melted and charred, and looks like it had a lot of current going through it.
Turning the key to the lights position at the input light connector with the motor off, is 0 V.
I don’t get 12V on the input light connector going to the lights either with the motor running. I also moved the light switch back to the lights position while it was running , and got 0 Volts.


#2

D

Danpoet

I ohmed the green wire from the G terminal of the starter switch to the green wire grounded through the bolt on the solenoid at the rear of the mower. It read 0 ohms.
I connected my battery charger to the wires for the lights. They both came on when I applied power.
I added a 20 amp inline fuse immediately before the lighting connector at the Geo t of the mower.
I started the mower, and the lights didn’t come on.
I turned the starter switch to the light position, and they didn’t come on then, either.
i checked the fuse, and it was blown.
Any troubleshooting ideas would be greatly appreciated at this point.


#3

D

Danpoet

Autocorrect changed my comment about
the lighting connector. It was supposed to read: at the front of the mower.


#4

D

Danpoet

I also replaced the lighting connector, as the terminals were charred and burnt.


#5

R

Rivets

Check DCV going to the lights from the key switch. Should be 12+ VDC. If zero your key switch may be bad or bad A2 connection. If you have voltage check for voltage on the second wire coming off the other light. According to the wiring diagram it looks like the lights are wired in series. (I haven’t seen series wiring on headlights in 2 years, but anything is possible). You said lights worked, so I would wire a jump lead to ground from the second light. Hope this makes sense.


#6

D

Danpoet

Rivets said:
Check DCV going to the lights from the key switch. Should be 12+ VDC. If zero your key switch may be bad or bad A2 connection. If you have voltage check for voltage on the second wire coming off the other light. According to the wiring diagram it looks like the lights are wired in series. (I haven’t seen series wiring on headlights in 2 years, but anything is possible). You said lights worked, so I would wire a jump lead to ground from the second light. Hope this makes sense.
Click to expand...


#7

D

Danpoet

I wired a 12v bulb to where the fuse holder was added. Started the mower, and no light yet. However, when I change the switch to the light position, the bulb lights up, indicating a short. I wiggled some harnesses around, but the short remains.
Any ideas as to the most likely culprit?


#8

D

Danpoet

The key switch is inaccessible normally, because it’s behind the gas tank.


#9

D

Danpoet

Danpoet said:
The key switch is inaccessible normally, because it’s behind the gas tank.
Click to expand...
The bulbs are wired in parallel. Blue wire to one side of the bulb, green to the other side.


#10

R

Rivets

Normally the green wire would be ground. Are you saying that you have two wires to each bulb, one blue and one green? Are you saying that you wired the fuse into the green wire? Are you saying the lights only come on when you turn the switch to the lights position with the engine running? If so I would say that you solved your problem, as the lights should only come on with the engine running. Sorry for the questions, but I’m not there to see what you have.


#11

ILENGINE

ILENGINE

Something to keep in mind is the light circuit may not show 12 volts DC because the lighting circuit could be AC. I am not sure what a DC meter will show when connected to AC.


#12

StarTech

StarTech

ILENGINE said:
Something to keep in mind is the light circuit may not show 12 volts DC because the lighting circuit could be AC. I am not sure what a DC meter will show when connected to AC.
Click to expand...
It is DC.
1682082854912.png


#13

D

Danpoet

Rivets said:
Normally the green wire would be ground. Are you saying that you have two wires to each bulb, one blue and one green? Are you saying that you wired the fuse into the green wire? Are you saying the lights only come on when you turn the switch to the lights position with the engine running? If so I would say that you solved your problem, as the lights should only come on with the engine running. Sorry for the questions, but I’m not there to see what you have.
Click to expand...
I wired the fuse into the green side. I replaced it with a 14v lamp in series with the green wire. When I go to lamps position after startup, the light comes on indicating a short somewhere.


#14

ILENGINE

ILENGINE

StarTech said:
It is DC.
View attachment 63979
Click to expand...
I would thinking AC because it shows the alternator wire without a regulator or diode straight to A2 and in the run 1 position it connects from A2 to L and then straight to headlights, and then goes to the ground side of the equation. I didn't see any place that it would connect to the rectified side of the alternator unless they are not showing the regulator. But they are also not showing a diode for the alternator to A1 connection.


#15

StarTech

StarTech

ILENGINE said:
I would thinking AC because it shows the alternator wire without a regulator or diode straight to A2 and in the run 1 position it connects from A2 to L and then straight to headlights, and then goes to the ground side of the equation. I didn't see any place that it would connect to the rectified side of the alternator unless they are not showing the regulator. But they are also not showing a diode for the alternator to A1 connection.
Click to expand...
Thanks for point out that connection and yes it would be AC in this case. I didn't have time this morning to go over the circuit in detail as customers were sitting in the driveway when I got here.

Forgive an old fart this morning I have been swapped with work for the last 1-1/2 months. Finally seeing a little daylight at the end of the tunnel.


#16

D

Danpoet

I understand completely! I’m an old fart myself. We are traveling this morning for our daughter’s bday and grandson as well. Can’t believe our daughter is 39!
Still not sure what to look for. Does look like a short of some kind?


#17

D

Danpoet

Do you think it has something to do with the alternator output?
I thought about disconnecting the A2 alternator wire, and running a wire from the B connection to the A2 terminal on the switch. I wouldn’t just run the lights from the battery without having the mower running, as it would run the battery down.
Do you think the added drain on the battery with it running would be made up by the alternator, or would it be an excessive current drain like it is now when I try to run the lights off the alternator output?


#18

D

Danpoet

I put a new connector for the lights, and added a fuse holder as well. Cleaned all the connectors with contact cleaner. The lights work, and the amp draw is only .3 amps.


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