Strange '93 Gauge Needles

[dockerguy]

As some may know, I just purchased a '93 ES300 with 109K on it. I knew the needles were a problem on this model. However, I've noticed something that I haven't seen mentioned in this forum:

If I start the car at night and then turn the headlights on, the needles are fine — they are bright and don't flicker at all. This has happened three consecutive nights while driving back home on a 45 minute trip. Going down during the day, the speedo and tach needles have dark areas while the temp gauge is fine, but the gas gague looks like a disco light show. Coming back at night they are all like new. However, if I turn the headlights on during the day, as an after thought, the needles still flicker. I need to start the car in the garage during the day, turn the headlights on and then see what the results are then.

Can anyone shed some light on this phenomenom? Could the flickering have something to do with the voltage? Has anyone else noticed this? I can't imagine that the electronics of the needles are bad if they work under a defined set of conditions. Skperformance said that Coode 21 on my HVAC display was a "Solar Sensor" error because I testd it in the garage. Could this sensor have anything to do with the flickering?

This really has me puzzled and I'm sure there's got to be a logical answer. Please don't tell me the car is haunted. javascript:emoticon('')

Thanks in advance for any information you guys might have.

Dockerguy

[norbertk]

I would send the cluster in to LexTech and get em replaced like I did.. I had the same problems.

[dropspace]

in the day, the lights are actually supposed to shine brighter on the display and needles. this puts added stress on the lighting element in the needle. If it is on the border of failing it will be more pronounced when the higher daytime power is applied to it.

there is one spot on my speedo needle that does the same thing. the lights are actually dimmer at night so the problem goes away.

you are going to have to get the whole assembly repaired to stop it as previously mentioned.

[SKperformance]

In my faq it also says that turnign the dimmer down will keep them from flickering as it is a voltage and heat problem causing intermittent to eventual blown spots.

[dockerguy]

Thanks, guys, for your help/advice. Just for the helluvit I turned the headlights on in the garage yesterday and then drove around in the bright sun and the needles were fine — bright and no flickering. I turned the headlights off and they started flickering immediately. I turned the headlights back on and they continuted to flicker, so turning the headlights on in a darkened area definately has something to do with it, but I'm resigned to getting the needles replaced.

I went to Lex Tech's web site, but I couldn't enlarge the photos of their products for some reason and it's difficult to tell anything from the small photos. I'll call them if I get the other problem I have resolved with the seller.

Thanks again!

[LLS]

Thanks, guys, for your help/advice.  Just for the helluvit I turned the headlights on in the garage yesterday and then drove around in the bright sun and the needles were fine — bright and no flickering.  I turned the headlights off and they started flickering immediately.  I turned the headlights back on and they continuted to flicker, so turning the headlights on in a darkened area definately has something to do with it, but I'm resigned to getting the needles replaced.

I went to Lex Tech's web site, but I couldn't enlarge the photos of their products for some reason and it's difficult to tell anything from the small photos.  I'll call them if I get the other problem I have resolved with the seller. 

Thanks again!

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Turn off your pop stopper?

[LLS]

You ask why your needles don't give you as much trouble with the headlights on. Try this experiment here:

go outside and turn your dimmer switch just off of the high position click (full on) down with your headlights off. Didnt make a hill of beans difference did it? NOW keep it in that position and turn the headlights on.

They dimmed! That's because the headlight circut will activate the second stage in the dimmer module when on and cut exactly .5 volt from the cluster. This is JUST ENOUGH to give the led's a slight break from "full voltage". That dimmer module is not just a knob, inside are a few chips and some diodes that regulate two lines to the cluster. one of them is full on (no headlights) one is controlled on (headlights on) which no matter what you do will always keep the cluster at .5 volt lower than the other way.

Why? Lexus didn't actually plan on this to happen (actually nippendenso since they make the unit). It is simple electronic theory, more easily said "it's the way it is" . :) See, whan you add a diode inline it drops the voltage of the line exactly .5 to .6 volt. This is one of the characteristics of the diode in an electronic circut. It just happens that you can see this little quirk of electronic technology since the needles that are sufficiently damaged are leaning on the brink of self destruction if that little tiny amount of energy is applied and helps finish overheating them.

You guy's wanna know the truth? That .5 volt extra is exactly what does the needles in...Nippendenso designed the clusters to run off of the dimmer module and never took into account what would happen if the headlights were off and bypassed the dimmer section #2 where the module kicks the diode in that saves the extra .5 volt. That's why they work fine with the headlights on.

In short......... Design flaw.

Why do the needles flicker?

-- They "dance" and flicker under the concept of the "flasher module" relay. If anyone has ever seen how a flasher module works, a small thin piece of aluminum is layed against a hot post when the post is "hot" it heats the piece of metal up and it bends away from the pole for about 1 second (just enough time to cool down and return). After the cool down, the metal returns to the pole and the process is repeated. It heats back up, pulls away from the pole and cools back down and returns. What you see..... is flashing! the contact touches, pulls away, then cools down and touches again. WHOLA! you have a flasher relay.

You also have a flasher needle too :) As the needle heats up it expands the contacts and they pull away. when they cool down about .4 tenths of a second later they come back, touch again, and bounce back off from expansion by the heat.

You basically have a flasher relay going on not by your choice. What this looks like, is a "dance" in the needle.

This should clear things up and if you need to ask anything else please feel free to email, I will be happy to help. It helps to get answers from an Engineer rather than a Technician. Techs just open units and replace parts, don't know why they failed, don't care, can't prevent it in the future.

Edited October 26, 2004 by SW03ES

[norbertk]

This man is brilliant.. ^^