Engine/Transmission (1994 - 1998) Forced to drive a Toyota.....

[jsjaastad]

Posted several weeks ago about my brake problem. 1995,4x4, 3/4 ton, 88,000 miles. After reading posts and archives I have done the following. I have a service manual and have followed the brake trouble shooting guide.

1. replaced the master cylinder

2. replaced the RWAL valve

3. replaced the vacuum check valve



I DO NOT HAVE any fault lights showing. Here is what it does. Drive down the road and do a 'panic stop', pedal goes clear to the floor,

but will slow to a stop.

Vac pump and booster check out okay, per the manual.

With the motor off and you pump up the brakes you can hear air escaping under the dash as you push down on the pedal. I am assuming it's coming from the aft diaphragm in the booster. My friend's 96 does not do this.

The brakes pump up good and you have good pedal. Push down on the pedal with minimal pressure, start the motor and the pedal (with minimal pressure) goes to the floor.

On my friend's 96, if you pump up the brakes (motor off), hold down on the pedal and start the motor, the pedal will dip down a bit and come right back up. What is wrong with mine?

I am forced to drive my Toyota (266,000 miles). If you can help, I would be thankful. Tom/Idaho

 

[hsmith]

Did you use new or reman MC? Did any of your repairs make any changes to the original problem?

 

[DSahd]

Not to be a smart A>>>>>>, but have you adjusted your rear brakes? (Wheel in the air ,turn adjuster with screwdriver until wheel is tight then back off till wheel just turns freely. Your symptoms sound as though you are out of piston travel, adjusting the brakes reduce the piston travel. I guess you have also checked the front disc pads???

Cheers Derek

 

[JoshPeters]

Sounds like it could be a Booster problem.

 

[KevinH]

i had the exact same thing wrong with my 95 i changed and bled all the brakes and replaced the dump valve. took it to the dealer and the said it was the brake controller module so they changed that then they called me back and told me that a brake line was corroded and busted. if i was you i would go through and check all the brakelines for leaks if there are no leaks i would say it is the brake controller module

 

[jsjaastad]

I used remanufactured master cylinder and RWAL valve and do realize that 'reman' is not as good as factory.

Rear has brand new shoes and are adjusted per the manual. Front disc have about 1000 miles on them and show very little wear.

The problems I have NOW are the exact ones I had before I started.

I can not find the 'brake controler module' in my service book? Is it called something else?

On page 5-7 of my service manual it makes reference to rebuilding the booster vac reserve. I cannot find that in the index, or are they talking about the booster itself, which the book also says is not rebuildable?

Once again thank you for your assistance. Tom/Idaho

 

[Grizzly]

Are you loosing brake fluid at the MC or any of the wheels?

 

[hsmith]

The module is under the dash to the right of steering column. Remove the knee bolster to access. Don't think that is your problem though, with no ABS light on.

If you are not losing fluid, I would suspect defective MC.

 

[cojhl2]

I wouild change the Booster!!

 

[RKerner]

i had the exact same thing wrong with my 95 i changed and bled all the brakes and replaced the dump valve. took it to the dealer and the said it was the brake controller module so they changed that then they called me back and told me that a brake line was corroded and busted. if i was you i would go through and check all the brakelines for leaks if there are no leaks i would say it is the brake controller module

I second this action, except for the brake controller thing. Sounds like they threw the controller on, it didn't fix the problem, and then correctly diagnosed the issue.



The pedal going to the floor is the result of a leak or air in the system. I used to just slowly press on the brake pedal with the engine off to diagnose pesky rear wheel cylinders and/or master cylinders. I assume you bench bled the master cylinder and then bled it at the line connections after installation. If not, loosening the line to the fronts should gravity bleed them and then bleed the rear brake fitting by opening it prior to pressing the brake pedal and closing it before the pedal hits the floor. This prevents air from being sucked back in due to "oops's" or mixing up the "down-up" routine.



A question a guy would have is "what do you mean by "the brakes pump up ok"?" Brakes really shouldn't have to be pumped up. This is another indicator of air or a really small leak as you shouldn't have enough slack in the rear brakes to require a second pump to get a firm pedal.



Maybe have someone listen to each rear brake to hear if the shoes are returning. If one brake is sluggish, the "return" squeak would not be heard. Or, find a dirt road and try increasing the brake pedal pressure until the wheels lock. Check the drag marks in the dirt and see which brake isn't working. Let us know how it works out.