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RABS CODE 4 Both brake lights on 90 Bii


A4LD_Nghtme

Well-Known Member
Joined
Nov 7, 2021
Messages
90
City
Twin Bridges, CA
Vehicle Year
1990
Transmission
Automatic
Hey there,
I have a 1990 Bronco II XLT 4x4 that has been edging ever closer to finish.
I've recently replaced the brakes almost in their entirety for the rear and still after bleeding the entire system have both the yellow and red brake lights illuminated and I now have a flashout CODE 4. Regardless of this the brakes feel good but something is amiss.

The changes/replacements I've done are:
Master cylinder
RABS Valve
Rear ABS Wheel sensor
Rear Brake hose
Drums
Shoes
Springs
Wheel cylinders
Passenger and driver parking brake cables

No leaks that I can see. Every other thread I've ever seen on this replaced something I've already replaced according to those threads so I'm throwing my line in the water.

Any info is appreciated that can help me tackle this brake issue before I just take her in to the shop.
 
Bad brake switch on brake pedal?
 
The red light indicates E-brake is on or switch malfunction / the brake fluid is low in the master cylinder reservoir or that switch is bad / low fluid pressure in the brake lines being either air in the lines or a leak in the system.

Code 4 for the RABS light indicates that a valve is stuck open/closed or so the book says. This could be the rabs module / wiring / or the valves itself which you mentioned you replaced.

Hope this info helps narrow the possibility's down for you.
 
Here are the pages for troubleshooting a rabs code 4 from the 89 shop manual.

IMG_5564.jpeg

IMG_5565.jpeg
IMG_5566.jpeg
 

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