Chasing a hard brake pedal issue

[jman11788]

I’m having issues with having to use a lot of effort to stop the truck.
I’ve been chasing it for awhile now as I’ve replaced some parts

New master cylinder
New brake booster
New calipers
Bled the system very liberally

I’ll also mention the ABS light is on. I have a about 7 codes for the ABS and I guess my next thing will be to replace the speed sensors. Also I have checked to see if the engine is pulling enough vacuum. My tool was reading 18-20” lbs of vacuum, so seemed good there.

After replacing all the parts and bleeding the system there was ZERO change. I’m thinking there maybe air in the ABS module but have no clue how to diagnose. Also if there is air in the module would I have to replace the unit and how easy it would be to replace. Thanks

 

[19963.4lsr5]

The vacuum check valve in the brake booster is know to do that when it fails.

Air in the system is usually associated with soft pedal feel and long travel.


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[Captsolo]

Take it to a professional brake shop and pay to have them fix. Throwing parts when you are not an expert is not the way to go with brakes, calipers, fluid, MC, air in line,

2005 4runner 150,000 miles SR5 1 brake job at professional shop where they do hundreds of brakes on all vehicles = $200 + parts / new calipers / new pads / rotors / test driveolice:.

 

[spartacus]

I’m having issues with having to use a lot of effort to stop the truck.
I’ve been chasing it for awhile now as I’ve replaced some parts

New master cylinder
New brake booster
New calipers
Bled the system very liberally

I’ll also mention the ABS light is on. I have a about 7 codes for the ABS and I guess my next thing will be to replace the speed sensors. Also I have checked to see if the engine is pulling enough vacuum. My tool was reading 18-20” lbs of vacuum, so seemed good there.

After replacing all the parts and bleeding the system there was ZERO change. I’m thinking there maybe air in the ABS module but have no clue how to diagnose. Also if there is air in the module would I have to replace the unit and how easy it would be to replace. Thanks

What are the codes. you can also clean the abs sensors at the wheels also check for vacuum leaks.

 

[jman11788]

What are the codes. you can also clean the abs sensors at the wheels also check for vacuum leaks.

Don't remember the codes. However, i cleaned all the sensors and the ABS light went off!! Still don't have much power assist to the brake pedal though. I'm almost certain its because there is air inside the ABS module..
If i replace this part do i have to bleed anything in the system? Or can i just bleed the one I have now ?

 

[spartacus]

Don't remember the codes. However, i cleaned all the sensors and the ABS light went off!! Still don't have much power assist to the brake pedal though. I'm almost certain its because there is air inside the ABS module..
If i replace this part do i have to bleed anything in the system? Or can i just bleed the one I have now ?

Assuming you bench bled the master cylinder before the install. Drive the truck on a gravel or dirt road if possible use the brakes so that the abs system kicks in a few times then take it back to where you can work on it and bleed the brakes with motor running and see if it helps. I still think there is a vacuum issue. My limited experience, hard brake pedal is always almost due to vacuum issues and brake booster. Air in the system normally leads to spongy brakes.

 

[19963.4lsr5]

I did front hoses and had a great pedal until the abs activated in the rain. Then pedal went to mush.

Bleed the brakes and firm pedal until abs activated but not as mushy as first time.

Third time was a charm. Pedal felt the same after abs activation.


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