abs light on diagnostic not reading help

[robiwill]

hopefully some one can assist with this one

got a gti anni mk3 taken in part x abs light and handbrake light are both on. annoyingly they werent on when the part x was agreed otherwise wouldnt have allowed so much on it so needs to be fixed
tried 4 different diagnostic machines and all are failing to read the abs to find the fault
checked all 4 sensors and appear fine

any ideas? hope some one can help or give me a few ideas cheers Robin

also the aircon is on all the time but dont think this could be linked

[DazVR6]

Usually when the abs light is on along with the handbrake light it means you have a problem with one of your rear sensers.

How did you check the sensers then, with a multi meter..?

[rubjonny]

im thinking either the abs unit has lost power or the diagnostic wire has come adrift.  Can you check the ECU diagnostics ok?
If so look up near the fusebox you should see the diagnostic port jumper block, will have yellow and white/grey wires going to it.  Make sure there arnt any loose plugs that look liek they should plug in here

Not sure where the ABS controller is, my guess would be under the rear seat, or maybe behind centrew console.  Look here for anything that looks off, and obv check all the fuses under the dash, and  any auxilery ones clipped above the fusebox, plus make sure there arnt any loose brown wires hanging down.

[robiwill]

cheers Jonny the diagnostics are reading everything else just not the ecu, the ecu for the abs is under the pump s this is a late spec the earlier oes where uder the seat, tried another abs euc and still no reading,
re the abs sensors just checked them by eyye as found with experience when they fail ususally due to being broken
had a few pms about not breaking an anni so going to spend some more time on it this weekend see if can cure the thing if not going to have to be broken as not letting a car on the rd with failed abs and handbrake light on as can lead to adverse breaking ie dangerous

[rubjonny]

ok cool, does point to a wiring fault if another ecu still aint cured it!  I'm pretty sure the abs diagnostic wire is grey/white, and airbags are yellow.  I have a wiring diagram for the diagnostics port & the immobilisor if it helps, can get you one specifically for the ABS/engine too if you get me the year

http://vwtech.no-ip.info/downloads/g3immobilisor.pdf
http://vwtech.no-ip.info/downloads/g3vagcom.pdf

[robiwill]

Cheers Jonny the year of the car is 1996 2litre agg going to tackle it sunday.

[rubjonny]

probably a bit liate now but heres the abs diagram:
http://vwtech.no-ip.info/downloads/g3abs95on.pdf

[Mikester]

i had these lights on, i would check the rear sensors, it was a front and rear sensor on mine, checking them with a multi meter would do the same as the fault code reader. Look for a restistance that is steeady between 1 and 1.2.

[robiwill]

sorta cured turned out to be a broken wire going to the abs pump added a new live and now will communicate through the diagnostic port right reat wheel sensor, before only checked em by eye as find usually they break rather than fail.
so an anniversary is saved from going into bean cans,
bought the car so will be prepped new cambelt etc and up for sale on auto trader soon
cheers for your help jonny