88 f350 idi rear anti-lock

[troy]

Ok I've replaced the master cylinder, the abs hydraulic unit under the cab on the frame rail, and I'm sure it was the abs differential sensor not a Vehicle Speed Sensor that I replaced, and the front calipers are new and the rear wheel cylinders were just replaced a couple days ago. I bled the whole system no bubbles... But the rear anti lock light is still on

. The light used to come on and once I started moving forward the light went off, lately the light has been on so I replaced the sensor... My question is was this a VSS sensor or an abs differential sensor?. And also could the trouble code still be causing the light to come on, and how do I clear it?

 

[troy]

I forgot to say that my brakes work great nice and stiff so I know nothing should be wrong but the light is bothering me

 

[DaveBen]

Did you bleed the anti-lock valve under the master cylinder? This will cause the light to come on.

Dave

 

[troy]

Did you bleed the anti-lock valve under the master cylinder? This will cause the light to come on.

Dave

Yes I did. I can always bleed it again just to be sure . but I went through almost a gallon of fluid bleeding the whole truck.
The sensor however I'm sure it had to be a abs sensor because my speedometer is cable driven. And I don't have cruise control . and my trans is a 5 spd. I don't see the need for it to be a speed sensor

 

[crash-harris]

If it's the truck in the avatar pic, the VSS is at the tailshaft of the transmission (t-case if 4x4) and the ABS sensor is on top of the rear differential.

Do a google search on how to pull the codes from the ABS unit and make sure the connectors for it under the truck are clean. You can flash the ABS codes out via the ABS light like you can with the gassers CEL light for the EEC-IV. I think the connector to ground out for code flashing is a black/orange stripe wire with a little harness on it hanging in the large wiring bundle under the left side of the dash. Been a long time since I did this so search the procedure first.

 

[troy]

If it's the truck in the avatar pic, the VSS is at the tailshaft of the transmission (t-case if 4x4) and the ABS sensor is on top of the rear differential.

Do a google search on how to pull the codes from the ABS unit and make sure the connectors for it under the truck are clean. You can flash the ABS codes out via the ABS light like you can with the gassers CEL light for the EEC-IV.

If the vss sensor is bad would that also cause the antilock light to come on?

 

[crash-harris]

I couldn't tell you for sure. I can't correctly reveal if the electronic pulses from the VSS are used for ABS or just for cruise control and engine management on gassers/electronic transmission control.

 

[snicklas]

Yes, the VSS sensor on the rear diff is for the ABS. If, its not working, the RABS will not work, and the light will be on.

Need to pull the codes, and verify online that you blead the RABS valve correctly. There is a correct way to bleed it......

 

[troy]

Yes, the VSS sensor on the rear diff is for the ABS. If, its not working, the RABS will not work, and the light will be on.

Need to pull the codes, and verify online that you blead the RABS valve correctly. There is a correct way to bleed it......

What is the correct way to bleed it?

 

[DaveBen]

Here is FTE's write-up on how to bleed the brake system; http://www.ford-trucks.com/forums/1162297-brake-bleeding.html

Dave

 

[jim x 3]

Troy,

Check the brake fluid level switch in the master cylinder. If fluid level is low or switch or connector is bad, this will (also) lite ABS.

Regards,
Jim