1993 Ranger ABS Light

[RangerLover49]

Greetings fellow ranger enthusiasts,
I have a 1993 Ford ranger which has the ABS light illuminated in the dash. I read a code of 4(Yellow REAR ANTILOCK Light Flashes 4 Times Red Brake Warning Light Iluminated RABS Valve Switch Closed or Open Dump Valve) except the red light isn't illuminated.
The hydraulic unit was leaking and has been replaced with a remanufactured one from O'Reilly's. This code implies something is wrong with that and it persists whether or not the unit is actually plugged In or not.
I have replaced the rear speed sensor and one of the rear wheel cylinders. What could be wrong with the ABS system?

 

[RobbieD]

The hydraulic unit was leaking and has been replaced with a remanufactured one from O'Reilly's. This code implies something is wrong with that and it persists whether or not the unit is actually plugged In or not.

Welcome to TRS.

Does your red Brake light come on and off as you engage and disengage the parking brake?

I had a case where the yellow Antilock light would not turn off after repairs, because my parking brake switch was dirty, and not operating the red light. After I made the red parking brake light operable, the yellow Antilock light reset. Based on that experience, I believe that the RABS system has to "see" the parking brake as part of the fault light reset.

 

[RangerLover49]

Does your red Brake light come on and off as you engage and disengage the parking brake?

The red light does work when the parking brake is engaged. It's funny you mention it though, because the red brake light has been acting... Strange. For the longest time, both lights were constantly illuminated despite the reservoir being full on the master cylinder. However, I bled the brakes again a couple days ago (the abs module was replaced over a year ago w/o working abs since) and the red light curiously went out the next day. It then turned back on, however so I played with the connector going to the reservoir and broke the clip and one of the pins on the connector. After stuffing it all back in the light hasn't come back on since unless the parking brake was engaged. The connector was extremely corroded. I might try some electrical cleaner on it and making sure it has contact.
Don't know if any of that information helps but from what I understand the red light should only be on when the reservoir is actually low and so it might be faulty? Not sure exactly.