Tims Toys
Member
Just bought a 790D, runs great, so far everything seems to operate correctly. Except the gauges. Nothing in the cluster lights up or moves. Any idea where to start? Already checked the fuse
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John Deere 790D gauges not working
- Thread starter Tims Toys
- Start date
mg2361
Senior Member
Welcome to HEF Tim
!
Fuse may be good but does the voltage reach the monitor panel? Is the ground for the monitor panel good?
!Fuse may be good but does the voltage reach the monitor panel? Is the ground for the monitor panel good?
Tims Toys
Member
Thanks. I’m definitely not an electrical genius when it is more than simple circuitry, but I have 12v at the gauges and sounded the alarm on multimeter when ohm the ground from chassis to different contacts on the board. Maybe I’m not testing properly, or need to perform other tests?
mg2361
Senior Member
With the instrument cluster plugged in gently backprobe the red/black wire (pin 1) and record the voltage (with the key on) and then do the same with the black wire (pin 23). Post the results.
Tims Toys
Member
Tims Toys
Member
I have these two plugs. Both start with number 1 and go up. The red wire on the small plug has 24.25v. Same plug has two black wires on other end. One has .22v, other nothing
mg2361
Senior Member
Post a picture of your monitor please. It is a "D" and not a straight 790 correct? The "D" is supposed to have 3 connectors. The straight 790 has 2 connectors.
Tims Toys
Member
Sorry, there is another small plug going to the bottom board. About 4 wires in a flat little plug. Maybe I’m missing another plug? Some of the wiring is suspect of somebody playing around not knowing what they’re doing. Found 2 wires with bullet connectors on them not hooked to anything and two black wires that dead end below the monitor
mg2361
Senior Member
Does your bulb check button light anything up?
The information I have shows only one power wire and one ground wire. I have limited information on the pin-outs of that monitor, so if you have a red wire with no trace color and it has 24V then power to the monitor is good. If you have a black wire with no trace color that has .22V (which is OK, but I would like to see .1V or less), try running a jumper from that black wire to a good ground to see if your monitor lights up. To lose power to both the gauges and the lights would have to be break in the power circuit just inside the monitor. You can take the monitor apart and look to see where the power comes in and follow the circuit board to see if there are any burned circuit paths. There are 2 circuit boards in there and they are both available from Deere. One of them is expensive at $2200, the other one is around $600. The monitor assembly is not available.
The information I have shows only one power wire and one ground wire. I have limited information on the pin-outs of that monitor, so if you have a red wire with no trace color and it has 24V then power to the monitor is good. If you have a black wire with no trace color that has .22V (which is OK, but I would like to see .1V or less), try running a jumper from that black wire to a good ground to see if your monitor lights up. To lose power to both the gauges and the lights would have to be break in the power circuit just inside the monitor. You can take the monitor apart and look to see where the power comes in and follow the circuit board to see if there are any burned circuit paths. There are 2 circuit boards in there and they are both available from Deere. One of them is expensive at $2200, the other one is around $600. The monitor assembly is not available.