Fiesta zetec s fault code U0121 ABS

stevos · 16-01-2010, 10:37 AM

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.

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oldford · 17-01-2010, 07:39 AM

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

andy milligan · 17-01-2010, 04:53 PM

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.

stevos · 10-09-2010, 06:25 PM

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

cabriolet · 11-09-2010, 09:53 PM

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

gbrosica · 27-09-2010, 11:14 AM

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?

10-09-2010, 06:25 PM	#4
stevos Too many posts.. I need a life!! Garage is empty, add now Trader Score: (0) Join Date: Nov 2007 Location: BONNY SCOTLAND Posts: 760 Rep Power: 5	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 __________________

27-09-2010, 11:14 AM	#6
gbrosica Virgin Garage is empty, add now Trader Score: (0) Join Date: Sep 2010 Location: Tadley Posts: 1 Rep Power: 0	Fiesta ABS ECU coding requirement 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? Last edited by gbrosica; 27-09-2010 at 11:19 AM.

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17-01-2010, 07:39 AM	#2
oldford Too many posts.. I need a life!! Garage is empty, add now Trader Score: (0) Join Date: Jan 2008 Location: Netherlands Posts: 616 Rep Power: 5	Could be a wiring problem just as well. Check ABS connector for signs of water ingress.

17-01-2010, 04:53 PM	#3
andy milligan newbe Garage is empty, add now Trader Score: (0) Join Date: Nov 2009 Location: surrey Posts: 58 Rep Power: 3	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.

11-09-2010, 09:53 PM	#5
cabriolet Too many posts.. I need a life!! Garage is empty, add now Trader Score: (0) Join Date: Oct 2006 Location: selsey Posts: 730 Rep Power: 6	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

27-09-2010, 11:14 AM
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