General ABS help please

[cptcuddles]

Hi

I have a couple of weeks until the MOT is due so I'm doing the jobs that I know need doing.

The ABS and brake warning lights usually both light after about a miles journey and have always done so in the six months I've had the car.

I've used fiatecuscan and have obtained code C1121 ABS/ESP relay which I cleared but it came back immediately. Now the abs unit is Kelsey-hayes and I've read the posts about the common fault.But are there any simple things that I should check first before changing the abs ecu unit.

Thanks for any advice

 

[maggers]

Assuming you have a wiring diagram all you can do is check all the feeds & earths are OK. If they are fine then it points to an internal fault. Do the lights come on if you just start the car and leave it running for a similar period of time that it takes to do a mile or so? If not then it may be a sensor fault, have a look at the ABS reluctor rings for cracks and continuity test the sensor wiring. The figure is'nt critical and may differ front to rear but each should be similar to the one on the other side.

 

[cptcuddles]

Maggers thanks for quick reply. Lights come on if engine just running on the driveway. Cleared the fault code and left laptop connected and fault re-appeared within a minute of starting the engine. Managed to find a wiring diagram online and will check all the feeds and earths before i do anything else.

 

[Neverth]

For the lucas unit there is guide to change the relay on FiatBOO
http://www.fiatboo.co.uk/photogal/guidepics/RepairingMareaABSunit.pdf

 

[cptcuddles]

Thanks for the link unfortunately thats not the ABS that I have. If it stops raining think get out with the multimeter at the weekend and check the external wiring to the ECU for supply. Can't see from the wiring diagram any external relays so will assume that if supply and earths are ok then the problem must be internal.

 

[Renegade_8]

The ECUs do suffer from dry joints. One poster on here removewd the ECU cut a hole in the case remade all the joints on the PCB and then sealed the unit again. Very brave, and it worked.

 

[portland_bill]

If the code relates to a relay, I would expect to find one somewhere. If not attached to the ABS unit, then in the main fuse/relay box under the bonnet. See if the handbook identifies where. Might need a new relay, or just cleaning of connections.

 

[cptcuddles]

Thanks for all the help guys as far as I can see the only relay is internal. I suppose I have nothing to lose in trying to take the case off and re-doing the joints worse thing I could do is not mend it and have to replace the ecu. I'll check all the feeds and earths first though. Out of interest does anyone know what the relays in the box in front of the battery are as on the lid there is an ABS symbol. I have a small black one a small red one and one larger black one not very descriptive I know.

 

[cptcuddles]

Just a quick update as its been sunny so I've been out with the multimeter. As far as I can see from the wiring diagram there are two direct 12v feeds from the battery via a 60A fuse and another feed via the ignition switch. With engine running all are getting approx 13.5V the two earths are ok to. Looks like a new ecu unit.

 

[portland_bill]

Out of interest does anyone know what the relays in the box in front of the battery are as on the lid there is an ABS symbol. I have a small black one a small red one and one larger black one not very descriptive I know.

This looks like a real possibility! Have you looked in the handbook? This should identify all the fuses and relays. If the fault code relates to a relay, it will be there somewhere.

 

[gigi1966]

hello guys, I'm gigi and i write from italy, i had the same problem of cptcuddles and i solved it by myself. I would like to share with you my experiece. I prepared a PDF in italian language but i don't know how i can load it

 

[portland_bill]

hello guys, I'm gigi and i write from italy, i had the same problem of cptcuddles and i solved it by myself. I would like to share with you my experiece. I prepared a PDF in italian language but i don't know how i can load it

To load the pdf file, click "reply", then click "Go Advanced". Below the reply box will be a few options that include "Manage Attachments". This should allow you to load the pdf file.

 

[cptcuddles]

Finally sorted. Obtained used pump via ebay unscrewed the ecu from the top and swapped with the one on the car all working fine now 5 mins to do.

 

[gigi1966]

ok, thank you portland bill.
Attached you can find my experience about ABS problem on my car.
I solved 3 years ago and after i didn't have problem.
If i have time, i'll translate the tutorial PDF
(sorry for my bed english)