I have an old, 2004 petrol Mondeo and for several weeks the ABS warning lamp comes on intermittently. Sometimes it doesn't happen for several days and I think it's gone away, but then there it is again! As it's intermittent I don't think it's a problem with any of the wheel sensors.
Thinking it might be the engine management computer I tried the trick of disconnecting the battery, headlamps on for 5 minutes, then reconnect. That cures the engine management lamp coming on due to the EGR valve, but it made no difference to the ABS lamp.

Any comments or suggestions gratefully received

 

You need to buy yourself a decent code reader which will tell you which wheel sensor is faulty. Or you could get a multimeter and disconnect each sensor in turn and measure their resistance. (800-2000 Ohms is good) However, a code reader is an investment if you've a mk3.  Can I recommend one of the best for Fords is from Tunnelrat electronics,   check 'em out on the interweb. Some generic code readers DON'T pick up all Ford car fault codes, but Tunnelrat ones running Forscan software (which is always being updated) is excellent.       It's no good guessing, so that's why you need a code reader which will find out why the ecu is putting the light on.. 

Thanks for that, I'll go for a Tunnelrat, looks good.

Do you happen to know whether the USB version will work with an iPad? I do not have a laptop, I have a desktop, but I don't suppose it's practical to use that with wifi, as as I can't be at the computer and the car at the same time .

Erm, no but if you email 'em (Steve Elmer) he'll advise.     I do know there's an Android version, and you have to pay a modest amount for the Forscan on that. In the meantime why not test the sensors with a multimeter? 

Thanks Nick

I asked Tunnelrat the question and surprised how quick they came back. If you're interested, their reply below (question same as I asked you). Didn't give a name so I don't know if it was Steve Elmer. I'll do what you suggest with a multimeter. I'll go for the USB version and borrow or buy a laptop.

Whereabouts in Leicestershire are you? I come from near Desford, now live near Stoke-on-Trent.

"Hi Roger,

It really depends on what you need to use it for.

The USB type can do everything but MUST be used with a Windows (XP to 10) laptop (very cheap to pick up secondhand).

The WiFi ELM is only for Android or iOS mobile devices. The USB Elm cannot work with your iPad.

As mentioned on our website already, the WiFi version cannot do module programming as WiFi or Bluetooth connections are not stable.

It can however be used to read and reset fault codes and perform some service features.

Unfortunately the Forscan app for mobile devices is not free. You would need to purchase it from the app store for around £6."