Major ABS problem, Need to identify the problem Options

[Panic]

I took my celi in for its MOT last weekend and it failed on the fact the ABS doesn't work. As it turns out the not very nice man (who I'd quite like to punch right now) has disconnected the light from the dash so it doesn't show up.

I need to know what the most likely problems are. It locks all four wheels under heavy braking and all the sensors and relays seem to be working and getting power. My mate is doing the repairs at his garage for me but hasn't worked on a 6th gen before

I really need help with this as I can't drive until I get it sorted

[opie_7afe]

diagnosing abs is a BIIIAAATCH!!!! ive been fighting with mine for a while now, finnaly got it down to all 4 abs sensors are done, the fronts were broke and some idiot just bolted the broken parts back up there, the backs just had no resistance between terminal and ground. first thing is pull codes, second thing is check your relays(better have the BGB open for this), third run secondary code search to diagnose speed sensor issues(if thats what it is), fourth check sensors themselves its the easiest part besides pulling codes, for the rear the sensor plug is inside the car behind rear seats on strut tower, test both sides,disconnect abs sensor from the harness. measure resistance between sensor terminals. resistance should be 800-2100 ohms, then measure resistance between each terminal to body ground, if it does not read more then one megohm it is a bad sensor. for the front the sensor connector is located under the splash shields, test resistance between the terminals it should read 600-1800 ohms. then test resistance from terminal to chassis ground. it should read one megohm or more. if it fails one or the other sensor is bad. this info is found on page 11 of the ABS portion of the BGB(if you have it downloaded and its individual pdf's.), i would not buy the sensors new if thats your problem they run at the cheapest 161$, luckily camry sensors will fit usdm hubs.(im not sure about the gt-four's or superstrut conversions) good luck diagnosing this pain in the rear ABS system,