1997 Isuzu Trooper ABS Light On, Flashes Code 53

[richamos1]

Hello everyone
I have a 97 Isuzu Trooper with 189k on it and the ABS light is on. I have shorted pins 4 and 12 which flashes the abs codes. It is flashing only code 53 which I believe is for the left rear sensor. I have checked the connections in the harnesses going to the back sensors and they all look ok. Do these sensors go bad in the rear? They are probably very expensive to replace. I also had a code PO401 which ended up being the EGR valve passages completely plugged. I cleaned out the passageways and cleared the code and it hasn't come back. I also have a CHECK TRANS light flashing and the check engine light on with a code P1870 Transmission Slip Code. I believe that I have one of them oil soaked alternators that a few of you have mentioned, should I take out the alternator and have it tested? Thanks for reading my book I will await an answer!
Rich