Hi:
New to this forum and looking for help. I just bought my first Lexus - 94 LS 400 off of a auction site. In spite of asking about the dash, LCD and needle displays (and being told they worked) the car arrived with the tach needle light out and the entire guage bulb display is out when the car is cold! As I'm sure you know the Lexus dealer wants big bucks ($1800) to fix these things. I have tried for help on several forums but no replies yet.
One ex-mechanic told me to clean the battery cables but another one told me I had to replace the circuit board and the tach needle.

I am willing to try to fix this myself. I called DENSO and they will not sell me a new board or exchange my board without going through the dealer. I have borrowed a used board (with another problem) that I can experiment on.

Questions:
- Can anyone tell me how (or point me to instructions) to change the tach needle after I have removed the guage cluster? The tach needle part number is 83242-50050.
- Has anyone found that a common component or solder joint goes bad on these boards that would cause a temperature-related complete outage of the lights while the temp, gas, seedometer and tach all still work? The circuit board part number is 83247-5A050RP.
-If I just buy a new circuit board and install it myself I understand it will show "0" mileage on the odometer. My car has 75,300 miles and I would like to keep it original - any suggestions on where I can go to set the correct mileage?

Im sure I'll eventually spend the $1800 on this Lexus doing some other upgrades - I just hate spending it on things that are already supposed to work. Thank you for any suggestions and help!

codylabrador

 

One option is to purchase a used dash from a junk yard and install that one. If you need to have the mileage set to reflect what you have on the car there are a couple companies that will do it for a small fee sometimes around 300-400.

 

the curcit board #2 is what you want they allways go out.it will change your milage though.

 

Thanks for the replies. Kevin - is circuit board #2 the small one attached to the larger one with ribbon cables?

I've now purchased an electronics manual for the LS 400. In tracing the ground I believe that the IH1 gound, which is on terminal 14 of the white connector, is common to the things that are going out on me. (See page 15 of the manual diagrams)

I cannot see an obvious break so I am thinking about splicing a wire into the backplane at some other point so the ground comes in from two directions. Anyone ever tried this?

 

Lexus uses a compact row of LED (light emitting diodes) to light the tach, speedo, fuel, and temp needles. Unfortunetly, the LED's don't seem to have the endurance to last in an older model cars (I have the same problem with part of my tach needle in my 95 ES300). I believe the newer models have a different lighting setup for the needles. The back lighting bulbs can be changed out with relative ease.

Your options, as I see it--

Call a salvage yard that has LS's and see if they will sell you a verified working speedo, tach, etc.. assembly. It wil be pricey, but not like a new one from a dealership. If you do happen to get a new needle(s) setup that is fully working, keep the lighting dimmer low to save needle life. (I know it sounds lame, but it has worked for me so far)

or

Someone on a different thread awhile back said that they found a guy that would sell them them the correct needle(s) by themselves. Word of caution!-- Removing a needle can be difficult, the needles have a very fine spring that carries the voltage to light the needle. If you were to try this, I would go very slow and be careful. (don't break the spring, or your screwed)

good luck

 

I OWN A LEXUS REPAIR SHOP IN PLANO TX. I HAVE A COMPANY THAT WILL REBUILD YOUR BOARD AND YOU KEEP THE EXISTING MILEAGE. EMAIL ME AND I WILL GIVE YOU THE INFO. EMAIL ADRESS IS DMOTORCO@AOL.COM.

 

Have your mechanic check into a company out of San Francisco, Mikado Technology (888-962-5236) or mikadotechnology@yahoo.com. They repaired my circuit board for a lot less than a new board. Plus it continues to show the original miles.

They fixed my circuit board and replaced the LCD for the climate control/clock and did a great job.

 

Hey codylabrador, while you were checking for broken connections did you check the capacitors? That's my theory (which I have been told is wrong but who cares you have one to test anyway).