The speedo in my 98 S Reg impreza turbo (UK Car) seems to stick at zero and then suddenly shoots to 30mph.

It is very inaccurate below 30mph as it just moves up and down when driving below this speed.

Any idea what might be causing this and what i have to do to fix it?

 

Might be worth having a feel up behind the dash to feel for the speedo cable. Mine had come loose a while back, just pushed it back on properly. Although mines an MY94, so yours may be different.

Worth a try and it costs nowt to check.

 

I think on 97 onwards uk facelift cars the speedo is electronically controlled rather than by cable, can anyone clarify this?

I also found that the speedo works fine when the car is cold but once it warms up then the speedo starts playing up.

Anyone else had this problem and what can i do to fix it?

 

Just been searching through old posts and found others have had the same problem.

Can anyone tell me where the speed sensor switch on the gearbox is?

A picture would be very useful if possible?

Thanks.

 

Im having a similar problem on my 99 WRX - the speedo has become very inaccurate, moving stiffly, reacting very slowly and just dropping when it hasnt reacted quick enough...

I got intouch with Protech who were very helpful and said it might be a faulty head... mines an import but were almost certain the speedo convertor unit isnt the problem, heres the reply I received from Dave at Protech....

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"It sounds to me like a speedo fault with the head itself, the easiest way to tell would be to remove the instruments and check for free movement of the needle. The speedo conversion won't make the needle slow as you describe."

"The needle should have a very smooth sprung action through the range and need very little pressure on the needle to move. From what you describe, I would expect a tightish needle on your speedo which would act the way you describe."

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Has any one else had any similar problems?

 

Ive managed to sort it.

I found that when the speedo wasnt working if i hit the dashboard it started working again.

So i removed the dash clocks, cleaned the connections and put it back together again.

Must have been a loose connection.

Seems to be working fine now so lets hope it stats that way.

 

Tried thumping dash but no joy!

Could it be the kmh / mph converter. Later car with electronic speedo.

Where is converter located and is it easy to bypass to check if OK before buying a new one?

 

The convertor is usually spliced/wired into the back of the speedo. Mine is the size of a ciggy box.(Intec speed convertor). I suppose you could bypass it by re-wiring it all but I doubt that is the cause. But no harm it checking the quality of the spliced/wires etc to see if they are soldered & sheilded correctly.
The speed sensor is located on the gearbox, you should be able to see it inbetween the turbo & tmic. If you need to remove it then its best to get the car up onto ramps or jack it up.
It could be a number of things, loose or bad connection on the wiring side.
Faulty speed sensor (gearbox)
Or faulty speed sensor (built in the speedo clock)

Ticky