I've been searching the forums for over two days and can't find the answer. Maybe someone can help.
I purchased a used cluster for my '92 SC400. I was told that it was out of a '94 SC400. I put it in a few days ago and was thrilled! The needles all worked and the back lighting was there, too! Wow! I hadn't seen that in years!
The next day I drove it. I noticed that everything seemed to be working right.
I was scootin' along and WOW the new cluster made me feel like I was going FASTER! Awesome! WRONG!
My speedo says one thing and I'm actually going about 20 percent faster! Look out! I have to keep an eye on the thing (and one out for the cops!) while I try to figure out what happened.
Again, I was told it was out of a 94 SC400. So, no problems with the tach. Just the speedo. Are the 92's and 94's geared differently? I found a post that listed final gear ratios and it looks like they're the same. I thought perhaps I got one out of a SC300 but the tachometer looks okay, I mean it doesn't look like my revs are different from before.
I'm lost....
Help???

 

Maybe it's possible that this cluster was removed from an Auto Trans SC300. I ran the car up to highway speeds and the tach does look like it's not "revving" as high. But, is there a difference in the transmissions that would cause the speedo to err so high?

 

Well, just for fun, I took it apart and re-installed it. It didn't change anything. The speedo still says I'm going slower than I really am. The cluster doesn't have the digital outside temperature gauge, so I'm assuming it's not a later model. It does have the regular PRND21 in the center, so I know it's out of an AT earlier model. I'm stumped!
Anyone?

 

the needles do physically come out of socket, when i had my needles re-done, there was some removing and putting back in the gas needle to get it right. in the process i knocked the speedo needle out and re-placed it, and it measures about 5-7 mph faster than i am really going. i am giving my 92 400sc to my 16 year-old, so am not going to change it.
see if the needle is dead on zero at rest. you can pull it off and re-set it, if needed.
good luck

 

Make sure needle is set at '0' with everthing off.

 

Thanks, Louie and KA. The needle is at zero at stop. I haven't pulled the needles. I just replaced the cluster with another one. Everything else works fine.

 

I agree. Check the needles and reinstall with them on dead 0.

 

My needles haven't been pulled. They ARE at the zero position when stopped, too. It's not that, guys. I appreciate your input. Has this happened to anyone else?

 

Could it be a worn motor for the speedo? It seems to me that the odometer is tracking true. I took it on the interstate yesterday and reset the trip odo and checked the mileage. Hard to do at 70 (or was it 80?) but it showed that one mile was just a tick over one mile... All I know was that I had someone follow me and when my speedo said 45 I was going about 55.
Weird problem.

 

A lot of people have looked at this thread! Wow. Still no answers, though. Anyone have an idea for me?

 

i have a friend with a 93 5speed sc300 that is having similar issues but his tach is not reading correctly either. only gas and temp gauges work correctly.

 

It could b from an sc3

 

My original thread....
No answers that have helped me pinpoint this problem.
https://www.clublexus.com/forums/sc-...-question.html

I took it out on the interstate today. Using the mileage markers as known distances I checked the odometer. The odometer reads correctly.
The speedo doesn't!

I used a GPS that tells land speed. The GPS is correct. I checked the time it took me to go five miles at 60 mph. Five minutes. The speedo read 42 mph the whole time! It kills me!

Is it possible that the signals to the cluster gauge use two different inputs for the speedo and odometer?

Is it possible that I may have a bad electric motor running the speedo?

Has anyone had this issue before?

Does anyone know the internal workings of the cluster unit?

Thanks for the input.

 

Has the speedo ever been opened up before? Sometimes people put the needle back on wrong.

 

Might be from an sc300 as mentioned on the previous thread. Is there a part number printed behind the cluster?