cdsl810 181 #1 Posted August 1, 2015 Guys, I'm only asking this because I am just too lazy today to take it apart and look. What bulbs are installed for the dashboard indicator lights on the 5xi series? The parts diagram that I looked at does not specify. Actually, it doesn't even list "bulb" anywhere in the parts list--just a "6 lamp harness". I also need the type of bulb found inside the 2 gauges, if they are different than the dashboard lights. I am planning an upgrade to LEDs for all these lights. I just finished upgrading the headlights and taillights today. Thanks! Share this post Link to post Share on other sites
Rick_in_CT 156 #2 Posted August 2, 2015 The dash bulbs are standard automotive bulb, #194. Can't say for sure, but I would guess that the gauges use the 194 as well.Good luck with the conversion. Let us know what you use to replace the 194.Rick Share this post Link to post Share on other sites
cdsl810 181 #3 Posted August 3, 2015 Well, I'm using the Sylvania Zevo LED 1156 bulbs for the headlights, their 194 counterparts for the taillights, and the Pilot indicator LEDs for the dashboard and gauges. I will post some pics when I get around to the retrofit.The Zevo LEDs are pricey, but very bright. The Pilots are reasonably priced and brighter/whiter than the standard 194. Share this post Link to post Share on other sites
bmsgaffer 2,052 #4 Posted August 3, 2015 yes, please post pics and let us know how evenly they light.I have been considering conversion to LEDs but wasn't sure if I would re-engineer an LED backplate for the gauge or just replace with ones commercially available. Share this post Link to post Share on other sites
cdsl810 181 #5 Posted August 7, 2015 (edited) Started working on the LED retrofit. It turns out that the Pilot LEDs are complete junk. Do not even bother trying them out. I purchased 8 of them (four 2-packs), and out of the 8, only 1 actually worked. I ended going with the Sylvania Zevo 194 instead. They are twice the price, but work flawlessly.The LED headlights and taillights are awesome. The LEDs in the dash were actually too bright and too white out of the box for my liking. My solution was to go to the local craft store and buy some colored glass/plastic stain (only $1.49). I painted the 194 lenses in the color that matches the indicator decal. Refer to the pictures below...I will post some final pictures when everything is back together. 20150804_192327.jpg 20150804_212214.jpg 20150804_212223.jpg 20150805_164804.jpg Edited August 7, 2015 by cdsl810 2 Share this post Link to post Share on other sites
cdsl810 181 #6 Posted August 19, 2015 The LED headlights and taillights work great--no modifications necessary. The dash lights (194 & 168) require a 50-Ohm, 5-Watt resistor to be wired in parallel to the bulb in order to work properly. They light up no problem without modification, but the electronics module freaks out without the resistors. The higher resistance of the LEDs fools the module into thinking that the oil pressure sensor, reverse PTO warning and battery lights associated sensors are "on". Put in the resistors and all is well. I took some photos, but they are not focused and don't really represent how the LEDs look. I will try it again with a real camera when I get a chance. Share this post Link to post Share on other sites
Save Old Iron 1,571 #7 Posted August 19, 2015 (edited) so the electronic module must monitor the filament in the indicator bulbs? interesting. Edited August 19, 2015 by Save Old Iron Share this post Link to post Share on other sites
WNYPCRepair 1,923 #8 Posted August 19, 2015 Don't you mean the lower resistance of the LEDs? If you are adding a resistor to make them work.... Share this post Link to post Share on other sites
cdsl810 181 #9 Posted August 19, 2015 (edited) Nope. The resistance of the LEDs is much higher than an incandescent bulb. If you put the resistor in series with the bulb, then it will add to the total resistance. Wiring a resistor in parallel with the bulb will actually lower the total resistance of the circuit. So, to simulate the resistance of the incandescent 194 or 168 bulb, the resistor is necessary to actually lower the high LED resistance to the lower range of the regular bulb. The formula for this is basically (R1*R2)/(R1+R2). Parallel resistance is always lower than the highest resistance found in the circuit. As a matter of fact, you can simply halve the resistance value of any resistance by putting the same value resistor in parallel. I can't remember the exact values I measured, but the regular 194 bulb had a low resistance of maybe 30 Ohms at 14V. The LED was 5 or 6 times higher than that. It just so happened that a 50 Ohm resistor got the circuit down to the necessary 30 Ohms or whatever I needed to match the 194 bulb from the 180-ish of the LED. so the electronic module must monitor the filament in the indicator bulbs? interesting. I don't think it monitors the filament. I think it simply senses changes in the resistance of the total circuit. So, with the LED in place without a parallel resistor, the module was getting a really high resistance and "thought" that the sensor associated with that indicator bulb was tripping. Specifically, the oil pressure warning light was flashing--like there was a problem... it was actually the resistance of the LED that caused this condition. Edited August 19, 2015 by cdsl810 needed to blather on some more 2 Share this post Link to post Share on other sites
Save Old Iron 1,571 #10 Posted August 19, 2015 (edited) Nope. The resistance of the LEDs is much higher than an incandescent bulb. As an assembly, yes, but once the actual LED element becomes forward biased, it becomes a literal dead short. The series resistor (maybe 680R to 1KR within the assembly) becomes the overall "resistance" of the bulb. This setup results in about 0.020 amps of current thru the bulb. The controller probably has enough leakage current thru its bulb driver circuit to still power the low demands of the LED. I initially thought a "bulb out" warning function is being used but on second though, why try to warn the operator by lighting a bulb that it believes is blown. So I fall back on my current leakage theory. See my next post #11.Other than a "cool factor", you are not saving any power by using the LED if you must use a 50 ohm parallel resistor to get the circuit to work.You are still blowing off 4 watts of heat (per bulb?) to allow LED operation. This just relocates the heat produced by the bulb to heating a resistor (which is hopefully mounted in a safe place). Edited August 19, 2015 by Save Old Iron Share this post Link to post Share on other sites
Save Old Iron 1,571 #11 Posted August 19, 2015 (edited) the LEDs fools the module into thinking that the oil pressure sensor ....are "on". Unless the 522 is vastly different than the 520lxi and 523dxi, the oil pressure light doesn't go thru a "controller", just a simple switch.Your hour meter is providing a continuous 20 ma path to ground thru the hour meter circuitry, still enough current to light the LED when the pressure switch opens under presence of oil pressure.I would also suggest making sure your hour meter keeps accurate time after using the LED substitute. The resistance of a filament in the #194 is very low when it is cold and that low resistance is what the hour meter counts on to gulp its power in surges every few seconds. It is now trying to draw power thru the 50 ohm resistor. It's worth checking.Nosing around with electrics can lead to surprising discoveries! Edited August 19, 2015 by Save Old Iron nothing better to do at 4:30 am 1 Share this post Link to post Share on other sites
cdsl810 181 #12 Posted August 19, 2015 My hour meter doesn't work, so I can't check the accuracy. I was only trying to use the LEDs for longevity and "the cool factor." I realized that when the LEDs required a resistor that the power consumption/current draw would end up being the same as the incandescent. That's actually a good point: the LEDs are only a power saving option IF they will work without any help. I am not recommending that anyone run out and spend a ton of money on LEDs that will require fussing around to get working properly. For the dash indicators it really doesn't make sense. This was more of an experiment than anything else. I had some time off work due to an injury--I was bored.I must point out that the LEDs did function well without the resistors, but the circuitry of the tractor was affected by their presence. There is a way to correct the problem without resistors, but it would mean rewiring the entire harness to isolate the dash indicators from everything else. I'm not going to waste my time... like I said, this was just an experiment because I had some extra time. At the end of it all, I would just avoid the LEDs in the dash.For the headlights and taillights however, I totally recommend the upgrade. There is nothing special required; they are a direct replacement. They are much brighter than the incandescent originals. I was able to mow last night in the dark without any issues. 1 Share this post Link to post Share on other sites
bmsgaffer 2,052 #13 Posted August 19, 2015 Thanks for reporting your findings! I would still be interested in the pictures!I plan on LED'ing the gauges in my 520H and will probably have to try a few things to make sure the light distributes properly. Share this post Link to post Share on other sites
cdsl810 181 #14 Posted August 19, 2015 The LEDs may work fine in the 520-H. There are no electronic modules that i am aware--don't quote me on that. Diffusion isn't a problem with the Sylvania LEDs. They are very even and bright. I wish my 520-H wasn't on vacation (at another property), or I would give it a try myself. Share this post Link to post Share on other sites
