2003 Ford Focus: intermittent speedometer connection?

Jodes · Mar 25, 2015

I've taken my Ford Focus 2003 to a number of garages, but none came to any conclusions about this. Few of them actually even managed to replicate the problem.

While driving, about a quarter of the time, the speedo shows zero even while moving. This also stops the distance counter from clocking any miles. (I am trying to get this fixed, honestly!!)

I'm having to resort to diagnose / fix this problem myself.

It usually only starts happening once it's been driven for 10 minutes or more. Then it flips from working to not working anywhere between every 2 minutes, to crazily a few times a second. So it surely is a loose connection somewhere. I haven't had a dig around at all, or looked at any circuit diagrams yet.

But my gut tells me it's going to be an electrical connection where there are vibrations. So I doubt it's the dash display unit, as surely other connections would be troubled, but particularly because it's not a harsh environment - it's in the cabin, relatively jolt-free and weather-free. I don't know where the computer that deals with the data is, but I suspect the problem is somewhere between the wheels and that computer,rather than between the computer and the display. Perhaps the dash is purely fed multiplexed digital signals, in which case the problem would definitely have to be between the wheels and the computer. But that's all just guesswork.

Opinions? What might the problem be? How could I diagnose it? Cost and effort of fixing?

Thanks!!

telectrix · Mar 25, 2015

i'd guess at a mechanical problem rather than electrical. the speedo drive from the gearbox being worn is a likely culprit.

Jodes · Mar 25, 2015

Thanks - Surprising though - wouldn't that make the speed vary, rather than just being zero or what it should be? E.g. when I go 30mph, it would only show zero or 30, not say 15?

Marvo · Mar 25, 2015

There's a powertrain control module that transmits speed info over the CAN network to the instrument cluster on the dashboard. The mileometer/odometer or whatever it's called also gets info from the PCM. You probably need someone with a plug-in diagnostic unit but you could try running through the self diagnostics to see if there's any interesting DTC codes.

[NOPARSE]http://www.fordownersclub.com/forums/topic/1486-focus-dashboard-secret-trick/?p=9406[/NOPARSE]

UNG · Mar 27, 2015

Does the vehicle have ABS? as a lot of speedo's use the offside front sensor for the speed information, a common problem in older cars are the reluctor rings on the CV joints they swell and / or crack this coupled with worn wheel bearings can cause this problem. As it only happens after 10 mins heat appears to be a factor which suggests a wheel bearing or sticking brake issue

Jodes · Mar 27, 2015

Yes it has ABS. Great information, thank you! Will be helpful while investigating.

PEG · Mar 30, 2015

Hi Jodes,that model has its' pickup on the gearbox,speedo issues quite a common problem.

A quick check on the ford forums will give you an idea.

Best case,sender/wiring at diff,worst case,dashboard replacement. Me dads was the sender,£20 odd,bit fiddly but cured it.

Try BBA web page,they sell the units,and have model specific common problem data.

Happy hunting.:icon12: