hi guys been having problems with ABS on the wifes fiesta we got it put on the machine this morning and it was showing the fault code U0121 data bus,anti-lock brake system control module- no communication.
We priced a module and it £400 but i just wanted to make sure it was the module before we bought it.

 

Could be a wiring problem just as well.
Check ABS connector for signs of water ingress.

 

Check you have power and earth to the ecu as if they are not there it will not fire up and there will be no communication. also wheck for broken or shorted wires from the abs ecu to the ecu that cant communicate with it.

 

Update for jackson.55

The problem we had was we lost speedo and abs light came on as well as handbrake light.
Found the problem to be with the ABS module its self.Ford want 500 pounds just to supply one.
I got one one from ebay for £50 delivered, Fitted it myself very easy job.
We had the car plugged into various different diagnostics and they all said no communication with abs module.
Hope this is helpful mate if you have any other question just ask.
Tried to pm you a message mate but your inbox is full

 

speedo not working gives this one away fellas bit of a fiddly job but not a problem to be honest the module is bloody expensive and one of the few that is not coded to the car lucky for u

 

I have exactly the same fault on my daughters Fiesta 2005 1250cc petrol: Speedo not working; ABS light, malfunction light and handbreak light constantly on. Fault code U0121 ABS Comms failure. I purchased a new ABS ECU from Ford (£400+) and wanted my local mechanic to fit it.

However, the instructions in the new ECU said you need to read the ECU code from the faulty unit and then afterwards program it into the new ECU.

My mechanic has now refused to do this job as he said he does not have the tool to read and write the ECU code. As the new ECU box has been opened Ford will not take back.

From this thread, it would seem that the Fiesta does not require writing of the coding to the ECU. I would really appreciate it if this could be confirmed by someone?

 

Hi,
Ive got exactly the same problem and looking to get the ABS replaced.

I've had my car to 3 garages. 2 of them say it is the main ECU and one says it's the ABS. Reading online confirms that it is definitely the ABS ECU. Rather than getting the original part and forking out 30% of my car value sounds ridiculous.

Can someone please help me in determining the exact parts that I need to get? i.e. is it the whole ABS pump and ecu that i need or is there something else as well? Modulator?! I am a newbie in this and appreciate experts help.