Will Is This All I Need To Replace The Speedometer For My 1996 Ls400?

[J-teck]

I don't know much about car and I'm only 15 and my dad don't know much about cars. So he tells me to order the parts and fix it for him. So I ran the car through a diagnostics and found out the rpm is about 500 lower than it should be and the mpg is about 10 lower. Is there any way to fix this without pay $$$ for repair it. also i found found a speedometer but i dont know if its the right one - Speedometer - can you please check this for me and see if its the correct one i need?

[cduluk]

Why are you under the impression that a new gauge cluster will fix your problem? Also be aware that when installing a new cluster the mileage will read to whichever car it came from...

[J-teck]

im only 15, and i dont know much about cars so im sorry if im making dumb questions/remarks

[turboomni]

You are not asking a dumb question at all J-teck. Although I don't have an answer for you or any experience with Lexus speedometers I would do a search here and see what comes up. There are people [i think in Texas even ] that repair speedometers for Lexus cars and if you send your unit in thay could tell you if the speedometer is the real problem or not.

What do you mean the rpm is 500 lower ,,at idle it reads 0 rpm's?/ And mpg is 10 mpg lower than what? Let us know more details .

Do a search and see,,, if the answer you need does not come up ask here again till someone with real info can help you and not answer your question with another question. That is of NO HELP when a member that acts like he knows something on the subject just asks you another question to stump you even more. That is BS .

That to me is a crappy way of helping someone,,especially a new member,,never mind he is 15 years old.

Good Grief

Do a search first and if you have more questions ask here again and hopefully someone with knowledge on the subject will actually give you some info. I know they are out there .

Good Luck Buddy

[J-teck]

i borrowed a friend's of mine odb2 and connect it to the computer, so yes it shows 0 when it is really at 500-600 rpm and when I go about 25mph it shows 13-15 mph on the dashboard

[killerFatty]

Hello I joined here when I was 14. I am now 17 and let me tell you I have learned more from here then I ever thought possible. The people are super nice...usually, and there is always someone who cares enough to find an answer to your question. You will probably need to have your gauge cluster rebuilt. The two faulty needles will likely need to be replaced. You can research places that rebuild lexus gauge clusters. I rebuilt mine myself and would offer to help you out but my car is first generation and yours is second generation so I doubt there will be many similarities. The good news is it sounds like a gauge cluster problem not a mechanical problem. Sorry I couldn't help more.

[J-teck]

oh, well ill just buy a new one and replace it, i also have another problem! I have the Nakamichi Sound System with a OEM Pioneer amp under the seat, the weird thing about the speakers is that it doesn't have much bass when I turn the fader to all 4 speakers but when i switch it to the front or to the back it gives out ALOT of kick, im just thinking that it gives out more power when i switch speakers and yes, the bass knob is maxed

[k_tieu]

might not be ur speedo could be a ur tach sensor and the wheel speed sensor never noe

[cduluk]

Speedometer and tach needles don't just "go out of calibration" in Lexus clusters... They don't work like that.

The issue must be with some types of sending units to those motors...

[killerFatty]

Speedometer and tach needles don't just "go out of calibration" in Lexus clusters... They don't work like that.

The issue must be with some types of sending units to those motors...

Mine did. My tach started reading a little low, then a little lower and now nothing. The needle is the culpret. I can wiggle the needle a little and get it to work temporarily, but that involves taking the whole cluster out just to pull on a needle, and it doesn't stay fixed long. I would also think that a speed sensor or other sending unit would throw a code.

[VBdenny]

Oh please, just put a GPS in there and check it.

[cduluk]

J-teck, can you provide more info on what the symptoms are? The soln all depends on what the issue is.

When you enter the car and turn the ignition to ACC (so engine off, dash lights ON) are the speedo and tach needles at 0? Or are they set at another position?

If they both read 0:

If the tach needle reads 0 RPM when the engine is off, and 0 RPM when the car's really working at 500 RPM, then it's not a minor calibration issue. If it were, the needle would read -500 RPM when the engine was OFF. There is no pin limiting the needle from physically moving below 0.

This is an indication that there is NO change in input to the needle motor whether OFF or when ON at 500RPM. IE: the needle motor is receiving the correct input at 0, but not at 500.

Same goes with the speedometer needle. If it reads 0 MPH when at rest, but is suddenly reading only 15 MPH when it's really going 25MPH, it's most likely not a problem with the motor. This too is an indication that the motors aren't receiving the correct inputs once the car is moving.

The needles are driven by stepper motors, which are VERY sensitive to input change. When the car is OFF (or at rest with the engine OFF) both needles are given a certain input to make them read 0. Even when the ignition is removed, there's a constant current being sent to the needles to keep them at the right positions. If you remove just the cluster cover while the car is OFF, you will feel resistance when trying to move the needles yourself. But, remove the cluster entirely from the car, and you'll be able to move the needles much more freely. And once you let go, they will remain in the very spots you left them in. The reason they stop wherever you leave them, is because of the friction in the clocksprings on the motor shafts themslves (sending voltage into the needles to make them light up).

Let's say you've removed the cluster from the car and manually move the needles to random positions (other than 0). Plug the cluster into the car, and the needles will immediately move back to their 0 positions. The only reason they always know where the 0 position is located, is because of the input current given to the 4 leads of the motors. Only 1 combination of current to each lead will yield a 0 reading.

So, if the needles are reading 0 when the car is OFF, then the motors are working. Otherwise, they'd be reading something different. There is NO way they can be reading accurately at 0, but not at another rate. If any single component in the motors were broken, they'd be reading inaccurately all of the time IE: off by a certain factor at all times.

BUT... if the needles DON'T read 0 when the car is OFF:

If the needles read below 0 (when ignition set to ACC with engine OFF) then the needles are most likely incorrectly calibrated. If the needles are ALWAYS +/- the SAME factor, then you might just need to realign the needles. In this case, the needle would read 0 RPM when it's really running at 500 RPM, and it would read -500 RPM when the car is OFF. For the speedometer, it would read 15 MPH when it's really traveling at 25 MPH, and would read -10 MPH when the car is OFF.

If your situation is the first, then there's an issue with the input being sent to the motors. I'm not sure if the issue is within the cluster or within the sending units from the cars computers... But if this is your case, i'm very doubtful that the cluster is to blame, as the only parts in the car that could read correctly at 0 yet be inaccurate at any other degree are the sensors themselves... It's easy for a sensor to understand that a car's NOT moving or that an engine is OFF, but more difficult to be accurate when they're running. If the cluster were to blame, it wouldn't be accurate at 0 and inaccurate at any other rate. The needles don't care what position they need to be at, as they do the same amount of work keeping a 0 position as they do keeping any other position.

However, i'm not totally sure how much of the computer systems that provide input to the needles are located in the cluster itself. I know the Rx300 and Rx400h both have these systems in the cars main ecu, but i'm not sure how they did it on the LS400...