ABS and Parking Brake light come on and stay (together) on until I restart truck and sometimes that does not help. I have replaced the master cylinder and flushed the brake lines. I have also changed the vacuum pump.

If I remember right, when I grounded out the brake wire in the cab, the abs light flashed 17 times (which if I have the right code sheet means nothing).

So my thinking is leading me to a faulty RABS valve or rear speed sensor. Anyone have a better sense of direction?

Thanks,
Paul

 

Both lights mean a fluid problem. Did your new master come with the reservoir? Corroded contacts on its connector used to cause this a lot.

 

It did come with new reservoir. That it what is throwing me for a loop. I thought the new M.C. would have taken care of it.

 

Look at the connector real good for corrosion and to make sure the 2 female ends are not loose or anything. I'd try to clean them out. There isn't much that will set off both lights like that. I had to replace the bottle on my last truck twice and replaced a lot of the whole things at the dealer.

 

I made sure of that when I took the old M.C. and put the new one in. The connector in the middle at the bottom of the reservoir and at the end of the M.C. look clean.

 

Well you got a weird one then I guess.
I think the rabs valve will only turn on the abs light if it fails. Unplug it and see if it's just the abs or both.

Have you spilled anything on the dashboard lately? The abs module is behind the glovebox. I think since it sounds like your lights come and go that maybe something is loose. I hope anyway. All I can think of now is to check all the connectors on it. If I remember right a fault that sets both lights on is supposed to keep them on till you cycle the key off and on again so that's probably normal.

Hows the pedal feel? When you bled it did you also bleed the rabs valve? It's got a bleeder on it.

 

I did not bleed the RABS. The pedal feels fine (A lot better than it did prior to the MC)

 

My lights came on a week or two ago and last night I lost brake pressure so I topped it off with brake fluid and today no more abs or parking brake light! It must have been the sensor on the master cylinder brake fluid reservoir.