Hello all, need some help with my '93 ext cab 150. Have been getting an ABS light and brake light. Seems to be random, truck will run one day without lights then next time out lights will come on after several stops. There appears to be no difference in the brakes. Pulled the codes and got code 4, went through all the wiring and found no defect. The Chilton and Haynes say bad RABS HCU valve but I'm too cheap to buy a new one for $200. Is there any way to rebuild it? Also I looked on another forum and a guy said he removed large nut on HCU valve and took the spring to fix his similar problem, is this a good idea?

 

Some good RABS Code 4 info here: RABS code 4 - what next? - FSB Forums

 

Did all the electrical checks and found nothing, but pulled drums to see if anything was suspicious there and found that driver's side wheel cyl was leaking only slightly. Flushed brake system and leak got way worse so replaced that wheel cyl. then noticed that e-brake cable on pass side was not releasing, had to replace cable. Now no ABS light and only code 16 (all ok) I guess code 4 does not just mean electrical problem.

 

Glad you found it