X485 problem -- is it the voltage regulator?

tpetty · May 17, 2011

Lately both the gas and temperature gauges have gone crazy on my X485. I ignored it at first, but now that I ran out of gas due to the faulty fuel gauge, I figure I should solve this.

Both gauges fluctuate, although the fuel gauge tends to stay "full" and the temp gauge tends to be "ice cold". I can affect the gauges even by turning the light switch. From internet search, with results NOT specific to the Deere, it seems like a bad voltage regulator could do this.

Does this make sense? I'm not a great mechanic, but I can certainly plug and unplug an electrical component if that seems the likely problem. Where is the voltage regulator?

beenthere · May 17, 2011

:welcome:
That is perplexing. Maybe a loose connection at the control board. I'd poke around there and see if something tickles the problem.

sunnyside360 · May 17, 2011

Deere had some defective fuel tank sending units some years ago. I bought my X485 new in the 2003 to 2004 time frame (don't remember exactly) and JD did a recall to change the sending units. They changed mine even though it was working at the time. Never had trouble with the temperature gauge or anything else for that matter to when I traded it for a larger tractor.

tpetty · May 17, 2011

The fuel sender seems like it should affect only the fuel gauge, I think this is a broader electrical issue.

Dutch445 · May 18, 2011

could be the dash unit, not much to repair,
usually just get replaced..

Mickey_Fx · May 18, 2011

I'm not familiar with this model or engine but here is my thoughts. Very common for engines used in LT's & GT's to have the A.C. rectified by the VR and voltage is controlled by shunting some power to ground .

So while the VR may be the component, I'm thinking you might want to check the voltage from the VR for A.C. component riding on a D.C. baseline. With some A.C. in the voltage, it could play **** with some components. Just need to hook up multimeter to line from VR and set on A.C. and see if there is any A.C. voltage on the line.

girardmustang · Sep 8, 2014

tpetty said:
Lately both the gas and temperature gauges have gone crazy on my X485. I ignored it at first, but now that I ran out of gas due to the faulty fuel gauge, I figure I should solve this.

Both gauges fluctuate, although the fuel gauge tends to stay "full" and the temp gauge tends to be "ice cold". I can affect the gauges even by turning the light switch. From internet search, with results NOT specific to the Deere, it seems like a bad voltage regulator could do this.

Does this make sense? I'm not a great mechanic, but I can certainly plug and unplug an electrical component if that seems the likely problem. Where is the voltage regulator?