gaz4x4cos

Good evening ,

just in the process of getting my cossie back on the road

its failed its mot on the abs light being on all the time 'indicating a fault with abs'
its been like this a while and drives fine.so far from threads on here i have checked the following.

-checked the cap that is ok and level is correct ( also bridged connector no difference)

-checked continuity of sensors all around 1100 give or take ,

-all relays appear to click when ignition turned (in fuse box and under the dash)

-fuses good and pump primes ,

-had sensors out and cleaned including pic up ring ,front two were cv greased up .

-rears were filthy, so were cleaned up when i fitted new pads & cleaned calipers up etc.

i want it mot'd so i can use it so can anyone help with the abs ecu plug pin out diagram so i can perform a few more checks with everything in situ to try and locate the fault ,

anything obvious I've missed , i know its been covered lots and apologise for asking AGAIN but could do with some more suggestions from those who know how annoying this problem is .

thanks in advance

Gary

Paul_RS

iTrader: (4)

Does the light come on after the car has driven, or does it stay on from the moment you turn the ignition on?

cossie891

iTrader: (1)

Mine is the same it stays on from the moment I turn the ignition on

gaz4x4cos

Hi, sorry for delay, it is on as soon as I turm on the ignition, its been on for at least 3 of the 6 years i've had it but it passed the last mot, its been laid up for 18 months, during the time I striped rear brakes down and cleaned drive shaft pick ups hoping that would have helped but it hasn't.
I would like to fix and have it working properly to see if it makes any difference to braking,as well as needing it for mot,but Most of all I want to use the thing again I think the bug has bitten again, since driving it the 8 miles I've managed so far!

Thanks

jon@work

iTrader: (5)

Try the following, and if no joy, I'll put up some more tests:

MAIN ELECTRO-VALVE TESTS

Located in the main brake unit.

All tests performed with ABS ECU unplugged and ignition switched OFF unless stated otherwise.

Resistance Test
-- Connect ohmmeter between ECU connector terminals 11 and 18. Resistance should be between 2 and 5 ohms.

• If resistance is not correct, remove 2-way connector from main electro-valve and check that the resistance across the two terminals is between 2 and 5 ohms.

o If electro-valve resistance is not correct, replace electro-valve.
o If the electro-valve resistance is OK, check for continuity between electro-valve connector (blue/white wire) and ECU connector terminal 18, and between electro-valve connector (brown wire) and earth.

Operation Test
-- Switch Ignition to position I
-- Wait for ABS pump to stop
-- Switch ignition OFF
-- With ABS ECU unplugged, connect short jumper wire between ECU connector terminals 2 & 18
-- Moderately depress brake pedal
-- Switch ignition to position II
-- Brake pedal should be felt to force its way up under the foot and become hard. If not, replace electro-valve.

CONTROL ELECTRO-VALVE TESTS

Located on the passenger side under the battery.

All tests performed with ABS ECU unplugged and ignition switched OFF unless stated otherwise.

Resistance Test 1
-- Connect ohmmeter between ECU connector terminals 1 and 11
-- Resistance should be lower than 1 ohm
-- If value is not correct, check for continuity between ECU connector terminal 11 and electro-valve connector terminal 7 (brown wire), and check that terminal 7 on the electro-valve (corresponding with the brown wire) is earthed.

Resistance Test 2
-- Connect ohmmeter between ECU connector terminals :

• 11 and 15
• 11 and 17
• 11 and 35
• 11 and 33
• 11 and 16
• 11 and 34

-- Resistance for each electro-valve should be between 3 and 7 ohms.
-- If not, remove connector from electro-valve, and check resistance between the following electro-valve terminals (the brown wire is terminal 7):

• 1 & 7
• 2 & 7
• 3 & 7
• 4 & 7
• 5 & 7
• 6 & 7

-- If one of the values is not correct (3 to 7 ohms), replace electro-valve/master cylinder assembly.
-- If the values are correct, check for continuity between control electro-valve connector and ECU connector.

• ABS ECU connector terminal 15 & electro-valve terminal 1
• ABS ECU connector terminal 34 & electro-valve terminal 2
• ABS ECU connector terminal 17 & electro-valve terminal 3
• ABS ECU connector terminal 33 & electro-valve terminal 4
• ABS ECU connector terminal 16 & electro-valve terminal 5
• ABS ECU connector terminal 35 & electro-valve terminal 6

gaz4x4cos

Thanks Jon,
I found this on another thread last night once i had checked the other bits, didn't think of just unplugging ecu and doing sensors from there to save faffng with back seat and under bonnet etc . Is the numbering of pins easy to identify once its unplugged in front of me, I'll report back once I have done.
Thanks for reply.
Gary.

dissmalrs

mine done the same thing it was the front sensor there is a rubber coating and it had worn away as shorted the sensor

Cosworth Lad

mines got same problem driving me nutts good luck mate will be keeping an good eye on this thread lol

gaz4x4cos

On mine one of the rubbers was gone complete on the front , but it tested out fine think it was 1086 ohm which is ok, would this rubber not being on cause the problem then?

I have a spare REAR one if I just plugged that in and tested with out locating in the hub cos there different , would the light go off if this is the problem or does the sensor need to be the correct one andlocated in the hub ?

Thanks

Gary.

Glenn_

iTrader: (1)

I would try it matey.i dont know if it will work on the front cause of the different resistences but its worth a try.


Im sure the wires on the abs ecu plug are numbered.Ive had a few problems with my abs system over the years and its always been sensors.

dissmalrs

when i tested mine it came up ok aswell iv also got a spair abs ecu if u want it

gaz4x4cos

i may take you up on that if i need it ends up being the problem . been out testing the system tonight but meter ran out of battery.

thanks

Gary.

gaz4x4cos

the numbering of the pins is on the ecu its self when i looked for anyones future reference.

i've been testing the valves tonight and found a few issues which don't match, i've pm'd jon with my fidings so far will await his expertese on these i'm going to test the sensors from the ecu plug once i can find the pin outs for them (i've seen em on one of your threads just need to find again,

thanks

Gary.

gaz4x4cos

i'll look at finding one replacement sensor too then.

Thanks

gary.

dissmalrs

was just thinking if u want to do a fast test

unplug the sensor (white clip under bonnet and under rear seats) do them 1 by 1 and turn the ignition on

the light should go out untill u move

if it dose then what ever sensor u have out is ur fault

the fault ur having is exactly same as mine and it was front right on mine

gaz4x4cos

Morning all, thanks for replies and just like to say jon@work has helped me diagnose the problem

gaz4x4cos

It was in the end my front drivers side sensor, after checking the entire system,plugged spare rear one in to see if it would go off and it did, so just waiting for a 2nd hand replacement from Gary @ rs classics then back in for mot and I can get some miles on her!!!