964 Speedo

[Dean Peach]

Hello guys, I've noticed my speedo stopped working today on my run around 964, can anyone give me some ideas what it could be and if it is a cable driven speedo where is it located and how do I get to it? Thanks in advance

 

[Dave Wilkinson]

Firstly, I'm afraid it's not a cable driven speedo, it's electronic. Depending on the year of the car, the early cars used a drive from the gearbox whereas the later ones use a signal from the ABS.

I presume your rear spoiler doesn't lift either?? (It's driven from the speed signal)

I had a similar intermittent problem with mine some years ago and the problem disappeared completely when I fixed the bad solder connections in the clock. Don't ask me to explain it but there are a lot of connections in the clock that affect the electronics in a lot of places.

Hope that helps.

Regards

Dave

 

[Dean Peach]

Thanks for that Dave, It's a 'H' plate C4, could it be a fuse then if it's electronic? I don't want to take it all the way over the a garage if I can sort it myself.

 

[Dean Peach]

Is there a fuse which could have blown for the speedo?

 

[Mark Elder]

I suspect only fuse covers all the instrument, but I had this problem a couple of years back and it turned out one of the connections on the back of the speedo had got pulled by a guy fitting a new radio. Was easy to fix once the speedo was out.

 

[Dean Peach]

Ok i've tried the fuse and it's still no good, what's the best way to get the speedo out?

 

[Mark Elder]

They come out with some manual twisting and pulling, but, generally, if they have not been out before, the bigger instruments are tougher to get out. So remove the clock first, then push the speedo from behind.

 

[Dean Peach]

Thanks Mark, I'll have a look now.

 

[chfs911]

Don't jump in with both feet yet!

1990 cars run from sensor on the side of the g50/3 gearbox. Signal goes to spoiler control under the LHS seat.

If the sensor fails the car picks up the speed from the RHR abs sensor and opens the spoiler at 115kph.

Check you are getting a signal from the G50 box speed sensor. Does the spoiler go up at 75mph?

If yes to both then it is posibly the speedo. or possibly the spoiler control box?

1991 cars used ABS signal only and the spoiler control was moved to the under dash area.