A 99 E-250 Van 5.4 with RABS. I have brake light and abs light staying on, I have replaced rear wheel speed sensor and did a complete fluid transfusion. Is there a special bleeding procedure for the modulator? I have seen another post recommending turning vehicle on during bleed to activate modulator. Anybody have anything on this?

 

So you have RABS not full 4 wheel ABS? If RABS bleed the brakes as normal and then bleed the RABS valve body after you have bled the rear brakes. Bleed with key off or on, makes no difference. Your lights on are probably caused by loose/dirty electrical connections at the master cylinder.

 

Is the RABS valve body the sane as the modulator mounted right underneath the master cylinder? If so how do you bleed it? i see no place to do that. THX

 

Are you sure it is RABS you have. The valve body for this is usually on the left side frame rail. Does the unit under the master cylinder have two pipes going to and four off it? However to bleed it whatever it is slacken the outlet pipes one at a time and bleed it thru the nut. It may be that you will need to get or make a pressure bleeder. But see how you get on.

 

It is RABS alright,It's got one goin in and one goin out to the rear wheels, I see nothin on the frame rail at all. I think I'll prob end up putting a new one on, but maybe i can try to bleed it at the outgoin nut correct?

 

Sounds similar to the Chevy one. Back off the nut on the outlet pipe and bleed it and re-tighten. However is your brake pedal good? If so then bleeding the brakes is not your problem. On the older Ford RABS system it is easy to pull the error codes, you may need to get this done to avoid throwing parts at it. Also the red light on only indicates low fluid, parking brake on and possibly low pressure in one circuit, it does not point to RABS faults. However low fluid level will turn on both lights. You may have a faulty level indicator in the resevoir or faulty connections to it. Sorry I can`t be more specific but I am only used to the older systems.

 

The pedal feels good, and both the red brake light and ABS light are always on. I will try the bleeding today, fluid level is good, where is the level indicator located is it a float inside or something? THX

 

OK, maybe you don`t have a fluid level sensor. It would be right there when you remove the resevoir top. Are your rear stop lights working? A failure there would turn your ABS light on (but not the red brake light). If you apply the parking brake does the red light get very, very slightly brighter? If not you may have a faulty/sticking parking brake warning light switch keeping the red light on all the time. However that would not put the ABS light on. The sensor in the rear axle that you replaced also works the speedometer, I take it that it is OK?

 

No change in lights when parking brake on. Speedometer is fine stop lights fine, Also just replaced rusted brake line to the rear and bled the systen real well so I think it's that modulator, vehicle has 207K prob needs it.
THX

 

OK no change in brightness of the red brake light means that the switch on your parking brake pedal is faulty/stuck/out of adjustment. Fix that first just in case the RABS does see it as a fault. At least it will put one light out.

 

sounds as if the valve you see is the proportioning valve
crawl under the truck and check the left frame rail
near the trans and the fuel filter
there should be the RABS controller mounted to the frame rail

 

Looked all around down there when i ran new brake line, I didn't see anything, so I'm thinkin it the thing up front. THX

 

I did adjust the parking brake switch so it is working, brake light changes when applied, but both the brake light and ABS are still on all the time. THX

 

Good. A pity it did not put the red light out. I have to come back to saying that both lights on together should be down to faulty wiring at the master cylinder. Has your master cylinder got a fluid level float? On the module under the master cylinder is there a seperate unit with a single wire going to it? Have you unplugged the wiring connectors at the module to see if the lights are still on? Have you tried cleaning the plug-in connections?

 

There is a plug with several wires that plugs into the unit under the master, also a switch for the cruise control with wires to it. I think all connections are good but will confirm. No, there is no master cyl. float. THX