brake and abs lights on

[boggerted]

After driving my truck, usually within the first fifteen minutes of driving both my abs and brake lights come on on the dash. I dont have any leaks that I can find, i never add brake fluid, and my brakes seem to work fine. what seems to be happening is the brakes work great until the light comes on, then once the light comes on i get less and less power assist until I basically have manual brakes. however if I shut the truck off and immediately start it back up i have power brakes again, so it seems like the light being on makes my brakes feel crappy. What would cause this to happen?

 

[MR.T]

After driving my truck, usually within the first fifteen minutes of driving both my abs and brake lights come on on the dash. I dont have any leaks that I can find, i never add brake fluid, and my brakes seem to work fine. what seems to be happening is the brakes work great until the light comes on, then once the light comes on i get less and less power assist until I basically have manual brakes. however if I shut the truck off and immediately start it back up i have power brakes again, so it seems like the light being on makes my brakes feel crappy. What would cause this to happen?

Getting "less and less power assist until I basically have manual brakes" sounds like a vacuum pump/leak problem. With the truck sitting still and the engine idling, pump the brakes and see what the light does.

 

[boggerted]

the vac pump was brand new, I thought it was that. I pumped the brakes with a vac gauge on the tree and it would slowly dip to zero and take a long time to return. Would the booster cause such a significant drop in vac?

 

[MR.T]

If it takes a long time to build vacuum, it's probably a big leak or a bad vacuum pump. To see if it's a leak: Shut the engine off and watch the temporary vacuum gauge -- if it's a leak it will drop to zero fast.

 

[7.3_IDI_guy]

Mighty ****** done this to me last week one time all the way home. I cut in off and left it alone for few hours and when I got back in it the light wasnt on anymore

 

[MR.T]

If it takes a long time to build vacuum, it's probably a big leak or a bad vacuum pump. To see if it's a leak: Shut the engine off and watch the temporary vacuum gauge -- if it's a leak it will drop to zero fast.

one more thing: If it's a leak (vacuum drops fast after turning engine off) -- start the engine and build vacuum again, pinch off the large vacuum hose going to the vac pump (with a c-clamp), shut the engine off and see if the vacuum drops off fast. If it holds now -- the leak is internal to the vac pump (check valves).

I'm on my third vac pump, and they can get intermittent problems (probably from check valves seating poorly).

 

[snowman89]

i would also check your proportion valve too

 

[boggerted]

if I shut the truck off it will hold vac for hours, so I dont think I have a leak. how would the proportioning valve cause the light?

 

[Dsl_Dog_Treat]

A little truck info in the sig would help.

If it's taking a long time to build vacuum then disconnect the booster and plug that line and see what the gauge does then.

My thought are from what you describe is a bad booster.

 

[gatorman21218]

And remember, just cuz its new dont mean it works

 

[boggerted]

I will check the booster and I know theres no guarantee on new parts so Ill isolate the pump as well. I also made an attempt to fill out my sig so hopefully it works lol

 

[Dsl_Dog_Treat]

I will check the booster and I know theres no guarantee on new parts so Ill isolate the pump as well. I also made an attempt to fill out my sig so hopefully it works lol

Nice ride too, by the way.

 

[fury9]

maybe there is air in the lines fix it before this happens-

 

[OLDBULL8]

maybe there is air in the lines fix it before this happens-

What?

No vacuum, lots of air in the lines!

Check your vacuum reservior, the tomato can. Might have arusted hole in it.