Speedometer not workin correctly, My speedometer measures like 20 mph faster than I'm driving Options

[celicabob]

Hey everyone. Im basically a newb when it comes to cars and I am hoping someone can help me out. I've got a 94 Gt auto and I think that the trannie may have been replaced,but I'm not sure. Anyways my speedometer is way off. I will be doing like 45 and it says I'm going 90 also some days it seems to be off by only about 10 or so mph. It seems to be more inaccurate on rainy days, but even on dry days it is slightly off. Can ayone tell me what is wrong and how it can be fixed. Any help will be appreciated.

[garin]

i've never heard of a speedometer being off by different variables on different days. i do know that tire size affects speedometers. bigger rims and tires make the speedometer read slower. your speedometer may have been tinkered with. someone could have taken the needle off and it may not be set right. dod you have glo gauges on? the needle can get caught on glo gauges if they are not firm against the oem gauge face. you could try to find an new cluster in a junk yard.

[celicabob]

Yeah, it is really weird how it is off different on different days, but it deffinately is. Actually I have a stock gauge face and cluster, but the car is used so maybe it was messed with. Is it difficult to swap a new gauge cluster in?

This post has been edited by celicabob: Nov 30, 2008 - 12:24 AM

[garin]

first time yes. but like any thing it become easier the more you do it. my car is apart like every other week. are your other gauges working fine?... tach, gas, temp. if they are you most likely have a cluster issue, not an electrical issue. i think it is the cluster though. figure out how to get it out and look at it. snap the black piece off that goes around the ignition. after that there are four screws holding that cover on. the cluster it self is held in with four screws, there are three plugs in the back. gl.

[celicabob]

Thanks for the replies. Yes, I think that the rest of the gauges work properly. I guess I need to go jukyard shopping and replace it. Is there very much wiring required to replace gauges?

[BonzaiCelica]

hmm ya my speedometer is off by 2 mph slower when im going 45. So your saying that bigger tires and rims make the speedometer go slower??

[garin]

no it all plugs in easily

hmm ya my speedometer is off by 2 mph slower when im going 45. So your saying that bigger tires and rims make the speedometer go slower??

yeah, the bigger rims take a longer time to make a full rotation. when the speedometer reads the speed it will be off slightly.

[celicabob]

If I switched speedometers from a junyard one that would only show the mileage on the junyard speedometer and not the original mileage on my car, right? I would like to avoid this. Is there any other way to fix this problem?

[garin]

yeah, i'm not sure how you can roll back the odometer. if you are up to it take the needle off and play around with it till it is calibrated properly. be careful not to break it though. i had to take my needles off when i put in glo gauges (i ended up taking my glo gauges out because they kept on burning out. never buy glo gauges, just do LED's). i took off the needle and turn on the car. placed the needle at 0 mph when it was at idle. i'm not sure if this will work, but try it if you feel confident. good luck. hope this helps.

[trdproven]

If you are sure its not the speedometer gear, it is likely it is the gauge cluster - happened to my 5sfe camry. off by like 20 miles or so.

[celicabob]

What is a speedometer gear? I will try to remove the needle, hopefully that will fix the problem.

[celicabob]

Well I replaced the gauge cluster with a new one and it is still off. I used a GPS and it is off sometimes by 20mph sometimes ony 5mph. Weird I guess I need to learn how to fix a speedometer gear. Does anyone have experience with the speedometer gear or is that a job for a professional mechanic.

[Batman722]

I just read this post, I wish I would of saw it a few days ago. It wouldn't be your cluster, all that does is display the signal it's recieving from the sensor.
It's probably your speed sensor. It's located on the top back of your tranny. It's a black connector with 3 wires coming out of it. Unplug it, remove the sensor (not simple but not too bad with the engine in the car) and replace it. Any 94-99ish toyota/lexus *should* have the same one, see if you can get one from a junkyard first then replace it in your car.

[celicabob]

Thanks for the reply Batman. It helped a lot.