hi there, i'm new to this, my sierra is not a real cosworth but a 2 litre dohc so as far as i know has the same abs system. the abs light on the dash goes out almost immediatly when the engine is started, but it comes on when you go over 10mph. ive checked the sensors and they all read between 1050-1100 ohms. i have also noticed there is no abs relay in the fusebox where the manual says there should be one. any suggestions?

any help would be greatly appreciated,
peter



heres a pic of it, my recently finished replica. i'm only 17 so a real one was never an option.

 

i,ll have a look at wireing the wire diagrams, your abs is practically the same as a cozzy,
where is the relay thats missing and we,ll see if we can sort it out.

 

nice tidy rep mate

 

in the fusebox beside the wiper motor, vii is written beside it and the handbook says that there should be an abs relay there

 

the relay VII in the fuse box is for the 4x4 sapphire cosworth only, the standard sierra pre 89 used it but had a different arangement.
the standard sapphire 1990 on has all its abs relays on the (M) relay module which is located under the dash at the r/h side of the passenger footwell around the lower corner of the glove box. it can be lowered down by undoing a screw/bolt for easier access.
relay m12 is the main abs relay, m13 in the abs pump relay 1
and m14 is abs pump relay2,
fuses 30,31,34 supply the 3 relays with main power, the relays are activated via the earthing through the abs computer.
with your problem the fact that the light is going out and then comming back on when you drive would indicate a speed sencing failure to me and that means sensors or sensor.
the do fail completly or can be intermittant.
fuse or relay failure will generally have the light on permanent and or the break pedal very hard.
you could check for continuity between pins 22,23,24,25 at the abs computer and their respective sensors, if thats ok then i would replace the front two sensors regardless of ohms readings, if that fails then replace the back two,it is expensive but it may be the only way to sort it as the system is generally reliable except for the sensors.
let me know how you get on

 

hi velocity, i have checked the AC voltage of each sensor at the connect while rotating the wheel at 1 revolution per second. the voltmeter we have has a 2 vac setting. the rear sensors read 0.1 vac each. the front left sensor was 0.03 vac. the front right sensor had no output. we changed the front right sensor and the output of this sensor was 0.02 vac. the light now stays out. when you are comin to a stop there is a small rattlin noise from the abs. we will buy 2 second hand sensors to replace the ones with low readings, and hopefully this will fix it fully.
thanks to everyone for their comments and suggestions on fixing the abs, peter

 

glad to see your 99% there.good work