B7500 HST - Removing the Dash, Accessing Switches

[Fiddlinmike]

I’m new to the forum and have spent an hour searching the comments before I bothered anyone with this question.

My tractor starts and runs fine, but the fuel gauge and temperature gauge just went dead. Apparently there’s a switch not working to power them somewhere behind the dash. Before I just start unbolting randomly, does anyone have advice and tips for pulling the dash on a B7500 and troubleshooting the switches? I think step one will be to buy a service manual. There are a couple options for that - any suggestions on a good one?

Thanks!

 

[PoTreeBoy]

I’m new to the forum and have spent an hour searching the comments before I bothered anyone with this question.

My tractor starts and runs fine, but the fuel gauge and temperature gauge just went dead. Apparently there’s a switch not working to power them somewhere behind the dash. Before I just start unbolting randomly, does anyone have advice and tips for pulling the dash on a B7500 and troubleshooting the switches? I think step one will be to buy a service manual. There are a couple options for that - any suggestions on a good one?

Thanks!

Welcome. I think there is a 10A fuse that supplies both gages. Check your fuses and fuse holders.

 

[jaxs]

Hopefully the fuse Poboy mentioned fixes it but if not I doubt wsm will be any help with removing dash. I say that because no Kubota manual I've seen gives details on r&r of parts. If wiring diagrams are included in manual you chose they can be very helpful.

 

[Fiddlinmike]

Welcome. I think there is a 10A fuse that supplies both gages. Check your fuses and fuse holders.

Thanks for responding! When I saw your note I was hopeful I had a blown fuse, but no such luck. All fuses are good.

I did discover how to access the area behind the gauges, so I’ll share some photos here for others…

There are two pry slots on top of the B7500 where you can insert a screwdriver and pop off the instrument panel (photo 1). Once open you can see the cable connected to the tachometer and a grouped cable going to a rubber-covered shield behind the fuel and temperature gage. (photo 2). If you remove the rubber shield you can see the cable splitting into multiple wires going into a circuit board driving the gauges.(photo 3.)

That’s where I stopped.

The grouped cable snakes back toward the engine on the “driver’s side” where the fuse box sits, containing 2-10 amp and 1-15 amp fuse.

Once I determined the fuses were good and all the connections were tight I arrived at the frustrating point of having to assume there’s something going wrong in the circuit board. Argggh… if that‘s the case I’m in trouble.

Supporting my theory that there’s something going on in the circuit board, I noticed that if I turn the lights or signal lights on, the temperature gauge moves. Energizing lights triggers the temperature gauge.

 

[PoTreeBoy]

Thanks for responding! When I saw your note I was hopeful I had a blown fuse, but no such luck. All fuses are good.

I did discover how to access the area behind the gauges, so I’ll share some photos here for others…

There are two pry slots on top of the B7500 where you can insert a screwdriver and pop off the instrument panel (photo 1). Once open you can see the cable connected to the tachometer and a grouped cable going to a rubber-covered shield behind the fuel and temperature gage. (photo 2). If you remove the rubber shield you can see the cable splitting into multiple wires going into a circuit board driving the gauges.(photo 3.)

That’s where I stopped.

The grouped cable snakes back toward the engine on the “driver’s side” where the fuse box sits, containing 2-10 amp and 1-15 amp fuse.

Once I determined the fuses were good and all the connections were tight I arrived at the frustrating point of having to assume there’s something going wrong in the circuit board. Argggh… if that‘s the case I’m in trouble.

Supporting my theory that there’s something going on in the circuit board, I noticed that if I turn the lights or signal lights on, the temperature gauge moves. Energizing lights triggers the temperature gauge.

I don't have a schematic for your tractor, but my L35 shows a mechanical voltage regulator on the circuit board that supplies the two gages. It has a contact that could corrode.

Other than that, I'd look for a dirty connection. You could try grounding the wire at each sensor and see if the gage goes full scale (or moves at all).

 

[Russell King]

You can try to send the dash to someone who knows how to repair it like this place

Instrument Cluster Repair - Domestic, Foreign Cars, Trucks

Circuit Board Medics professionally repair foreign and domestic instrument clusters for car owners and business alike. Click here to learn more.

circuitboardmedics.com

I would try to clean the contacts first though

 

[Fiddlinmike]

@PoTreeBoy @Russell King @jaxs

Success!

Thanks to all of you who gave me advice. I’m going to finish the story for anyone out there who has a B7500 and simultaneously loses their gas and temperature gages.

I pulled the panel as described above and then disconnected the tachometer cable and multi-wire connection. That allowed me to fully remove the instrument panel and get a good look. The attached photo is what I saw. The bottom 6 leads had oxidized to the point they were not making good contact. Once I cleaned them up and reattached the panel my gauges started working again.

You guys were right about that being a possibility.

By the way, there didn’t appear to be any other components in this panel board apart from the metal leads to gauges and warning lights.

I hope this experience helps someone else. Thanks again!

-Mike

 

[PoTreeBoy]

@PoTreeBoy @Russell King @jaxs

View attachment 115250 Success!

Thanks to all of you who gave me advice. I’m going to finish the story for anyone out there who has a B7500 and simultaneously loses their gas and temperature gages.

I pulled the panel as described above and then disconnected the tachometer cable and multi-wire connection. That allowed me to fully remove the instrument panel and get a good look. The attached photo is what I saw. The bottom 6 leads had oxidized to the point they were not making good contact. Once I cleaned them up and reattached the panel my gauges started working again.

You guys were right about that being a possibility.

By the way, there didn’t appear to be any other components in this panel board apart from the metal leads to gauges and warning lights.

I hope this experience helps someone else. Thanks again!

-Mike

Glad you got it fixed and thanks for coming back. Someone else probably has the same problem. I like to use a little dielectric grease on areas like that to keep moisture away.

 

[GreensvilleJay]

You can also 'tin' those 'fingers', BTDT many,many times ( once per problem cluster..)

 

[jaxs]

It is very considerate of you Mike for posting the conclusion and picture,many people fail to realize how valuable that is to people with similar symptoms.