Now THAT'S a good idea! Why didn't I think of that??? Ok, that might just work, but it'll be a while before I can try - I think. Have lots on the burner with Dad's house, getting ready to go on a mini-vacation/best friend's funeral (where I "get" to speak), and then on to Thanksgiving. Probably 3000 miles of driving, half of which may be in the truck.

 

Guys - Kyle (first today) sent me a link to a Jeep forum where they've discussed the use of LED lighting for the gauges. Here's a link to the last page of the thread where things are summarized: Jeep.

And, here's an interesting picture from that thread where a guy used a "cool white" LED on the left and a stock 194 bulb on the right. Doesn't the one on the right remind you of our gauges?



I think I'm going to order some of the LED's just to play with them since they are so inexpensive. I'm thinking I'll go with the 120˚ Cool Whites.

Thanks again, Kyle.

 

Glad it gives you something else to think about. This is what the gauges look like out of the circle housing.

1992 95 Jeep Wrangler YJ Replacement Water Temperature Gauge USA Fahrenheit | eBay

http://www.ebay.com/itm/JEEP-WRANGLE...4c1c9d&vxp=mtr

http://www.ebay.com/itm/92-95-OEM-JE...4db494&vxp=mtr

 

The LED-lit gauges don't look any brighter, just whiter.

 

I agree with that observation.

Think of one large mirror reflecting light, then think of 1000's of smaller mirrors reflecting the same light in different directions due to them not being flat. An uneven painted surface can diffuse the light the same way. The result is the light will look dimmer than if it was high gloss polished surface.

I would also investigate the white painted markings on the gauges themselves. The paint could be extremely weathered and chalky. This would cause the light not to reflect like it should off the gauge markings itself; in the same way that the plastic has. Ideally you should not see any or very little light reflect back off the black surface of the gauges, only bright markings with bright needles etc... Repainting the gauge markings themselves with white, (or reflective white paint used for road markings), and flourecent orange or flourecent red for the needles, along with what you are doing with the back surface might be warranted.

You can buy paint markers for detailed work at hobby shops, craft stores etc...

 

I posted this in Dad's Truck Build just now, but thought it should go here as well.

I worked on the dash light issue a bit today. What I did was to wait until it was dark and photographed the instruments with the original bezel with the browned backside, and with the bezel I painted white on the backside. The pictures are in that order, with the browned bezel on first and the painted bezel second. I don't know about you, but to me it makes a noticeable difference.

But, I should say a few words about how I took the pictures. First, if you leave the camera in automagic mode you won't see any difference whatsoever in the pictures, no matter how bright (within reason) the instruments are. That's because cameras have complex metering systems that are programmed to give a balanced exposure regardless of the amount of light. So, if your "after" instrument lighting is twice as bright as the "before" lighting the camera will adjust the exposure to make the picture look like the "before" picture. (Depending on the mode you have it in it will either cut the shutter time in half or stop the lens down to adjust.)

So, what I did was to take a picture on automatic, actually Program mode, to see what the camera thought it should have in the way of shutter speed and lens opening, called aperture. But, knowing how dark it was, and therefore that the shutter time was going to be long, I put the camera on a tripod and used self-timer mode so I didn't shake anything by pushing the button. Anyway, the shot in Program was 1 second long with an aperture of f2.8. So, I turned the mode to Manual and dialed in those settings so they couldn't change. And then I took the before and after pictures. (But, when comparing them I happened to look at the initial shot in Program and discovered that it was significantly brighter, so the camera actually used a shutter speed longer than 1 second but less than 2 seconds. And, since there isn't a manual setting between those two times I guess it didn't bother to tell me.)

Anyway, the bottom line on the lighting is that the browned back of the bezel is cutting the light significantly. So, I think the first step is to paint the back of the bezel. But, don't do as I did and use spray paint since I ruined a bezel when the overspray messed up the front of the bezel. I think I'll do as first today suggested and tape the edges w/o folding the tape over. And then I'll brush some white paint on and call it good.

But, in the interim I've installed the painted bezel and will try it to see if the gauges look as bright in operation as they seem at first blush. We are taking the truck up to see Dad tomorrow and will probably be driving after dark, so may get a good reading then.

 

Another thought: A way to find out how much brighter the instruments are is to put the camera into Aperture mode so the f-stop can be fixed, but the camera can select the shutter speed to control the exposure. Take a picture and see how long the shutter was open in comparison to the original shutter speed and you'll know how bright the instruments are after your change. However, I suspect that the metering systems on most cameras aren't linear with respect to the wavelength of the light, so installing LED's would probably throw a spanner in the works.

 

What kind of filters are you using to get the red color on the lights?

The reason why I say this is because light has three primary colors. Red - Blue - Green, or RGB (the same on your tv set).

The original factory color is Blue/Green. This filters the red light out of the white light and you are left with blue/green etc... Or it's 1/3 dimmer than white itself.

With the red, you are filtering out both blue and green to get red, so 2/3 dimmer than white...

Changing the color back to a blue/green, or doing plain white would make it brighter, etc...

 

Actually, I'm not using any filters. Took the blue filters out and am running clean incandescent bulbs with the rheostat all the way up. However, when those pics were taken the engine wasn't running and the headlights were on full. So, the voltage to the dash lights was lower than it would have been when in normal use. And low voltage gives yellow light.

Had the pics been taken with a film camera I would have thought we had reciprocity failure where the long shutter times favored the red end of the spectrum. But, this is the digital age so that's not the problem. I'm guessing it is a combo of the white balance, which was in auto mode, not working perfectly and the screens/monitors each of us are using. For instance, on my shop computer the shots aren't very dark nor red and there is a significant difference between them. On this computer they are red, although not too dark, and there is a difference between them. However, on my iPhone they are dark and red and there is very little difference between them.

So, what you see on your computer may not be what I see on mine. And, what I see on mine varies by computer. But, what I see in real life isn't quite what I see on any of my computers. I drove for a couple of hours in the dark tonight and I can say with certainty that the gauges are noticeable brighter. Not quite where I want them, but better than with the browned bezel. And, they are somewhat yellow but certainly not red.

 

Ah...

The pictures I see look very "Red". Looks like you have red filters on the lights to me. If not orange...

Incandecent bulbs glow toward the red and green end of the electromagnetic spectrum because of resistance in the filaments or wiring. The more resistance the more it shifts toward the red. IE: when you dim the lights with the rheostat, it gets "yellower".

Hence the yellowish color you are seeing.

 

Yep. Which is why I'll probably go with the cool-white LED's at some point.

And, by the way, I just had a thought about the voltage drop at the instrument lights if the headlights are run off the switch vs having the relays installed and the headlights running off the solenoid. As best I can measure it there's at least .25 volt drop with the headlights pulling power through the switch and with them just off. But, there are at least two problems with reading the voltage as I did. First, I'm not sure what the source of power is for the instrument lights. In my 81 Truck Wiring Diagram book the source of power into that part of the headlight switch is Circuit #195, but unless there's a junction missing in the diagram just above the switch where 195 crosses Circuit 38 there is no source of power. But, if it does actually get powered by #38 then there will be a voltage drop across the fusible link as well as all the wiring 'tween the battery and wherever #195 gets its power. Does anyone know the source of power for #195?

Second, by just turning the headlights off the voltage of the whole system goes up a bit due to the loss of load. But, it looks like maybe a quarter volt improvement at the gauge lights w/o the headlights pulling power through the switch. And, that's gotta help some as every little bit on the top end makes an improvement.

 

My book shows Circuit 195 - tan/white-stripe - is fed by F8¹ in the fuse panel (15-A fuse, services Parking Lamps, Tail Lamps).

But I doubt this is what you're looking for...

As I understand it...

Power comes into the headlight switch through a black/orange-stripe wire serviced by a fusible link at the starter solenoid.

The headlight switch has a circuit breaker for the headlights.

Power then runs from the headlight switch to the fuse panel; from there, Circuit 19 (light-blue/red) is distributed via Fuse F1¹, a 5-amp fuse servicing the instrument lamps.

Might try this test with the blower motor, too, just for kicks.

¹ As shown in the Wiring Diagrams manual not the EVTM.

 

Ok, I think the mystery is solved: In the first picture you can see that 195 connects to the bus in the fuse block, and that bus is fed from circuit 38 off the fusible link. Then 195 puts power to the rheostat when the switch is pulled either one or two notches, and the wiper picks it up and sends it to the gauge lights via Fuse 1. So, the instrument lights DO get power from the same place the headlights do - Circuit 38. And, changing that so the headlight power comes from the solenoid should help as the huge current draw of the headlights across the fusible link, the small gauge wire, and the many connections will be gone.





Why?

 

Correct. The headlamp switch is a multi switch with various switches inside.

Circut 38 is not connected to Circut 195 where you have it circled though. That is just where the lines cross in the diagram. Where the circuts connect is at the fuse buss bar inside the fuse panel.


Circut 38 powers: F-4, F-5, F,7 and F-8 at the fuse panel. Basicly all the fuse functions not controlled by the ignition switch.


F-4: Yellow Light Blue: Cigar Lighter and Horn
F-5: Power door locks, Electric mirrors...
F-7: Light Green and Yellow: Protection and convenience
F-8: Tan White: Headlamp switch to Brown Parking lamp circut, and Light Blue/Red instrument cluster illumination.


Circut 38 also powers the headlamp switch directly for the headlamps.



The main draw from the headlamps would be gone yes. That would leave more for the other circuts in the fuse panel powered by Circut 38.

 

So, what you see in the picture of the schematic has the circle??? The one I see doesn't, so I didn't mention it. Odd. Is the one you see properly oriented?

Anyway, I put the circle on when I thought the schematic was wrong, but then it dawned on me that 195 is fed off the fuse panel and that the schematic is correct. However, since I didn't see the circle I assumed you wouldn't and didn't mention nor worry about it.

Also, by moving the headlight load to the solenoid we are bypassing the shunt, so the ammeter won't register the draw of the headlights if the alternator fails. That's another reason to have a volt meter as well.

And last, I'm just finishing dinner and then heading back out to put the last details on the home-made relay harness. It is on and works, but I have some things to finish and pictures to take - just to prove to Shaun I did it. I'll post those in Dad's Truck Build.