Chasing ABS/TC issues

AGENTKB

hi guys, I had an issue with my ABS on front left side (broken wires) then sometime later I replaced said hub. now a second issue has appeared with the right hand side so ran a substitute wire straight to the speed sensor and hey presto it bloody worked no more lights on dash. oh yeah this is 2 days before mot so well happy. now 40 mins before mot and I go out for drive to warm out the engine for emissions and there it is the ABS/TC lights come back on!. so quickly got back home plugged it up and it says front left and rear right problems now. checked the wiring all good and needless to say I missed my mot ffs. Any ideas??????Nothing was touched after it was fixed and ABS lights were off.

gsi2000

Hi, when you say it appeared on the right hand side, is that front right?

AGENTKB

started on front left then front right now rear right.

gsi2000

Id be tempted to remove the substitute wire, plug connections back in as they should be, clear everything with opcom and take it for a drive.
see what codes (if any) re-appear.

AGENTKB

Wasnt getting any continuity with the wiring to the wheel

gsi2000

Not sure you will if abs light is on because it disables abs system. (i could be wrong on that tho)
When you check readings from each sensor (as well as spinning the wheel while measuring readings) jot the figures down to check they all are giving very similar figures, will pin point if any of the sensors are faulty, next stage will be checking all abs related fuses and cleaning abs ecu connector plug with contact cleaner, if that fails then your looking for a broken wire or bad earth.
What codes are coming up with op-com?

AGENTKB

All sensors were giving same mph reading, i checked fuses and cleaned the connection block. Im thinking bad earth cause thats the only thing left well or a bad ecu.cant remember specific code just right rear low voltage or something. Can check tomorrow

gsi2000

from experience i wouldnt say ecu would be bad, more than likely wiring from connection block in wheel arches back to ecu somewhere, is it a vectra?

AGENTKB

Just weird that after I fixed it another one stops after it just sitting there. Its a z22yh vectra C. But i guess its an old car now 54 plate

gsi2000

sometimes fixing problems (especially electrical) un-earths more problems further on, year of the car the wires can become brittle and break up inside, i will check on my vectra tomorrow for sure, but there may be a connector for the speed sensors somewhere near the fuel tank.