Having issues with my brake pedal going to the floor when stopped. It stops just fine as long as I don't turn the steering wheel when stopping but as soon as I turn the wheel the pedal travel to the floor seems directly related to the turning of the steering wheel. I know it's most likely the master cylinder as I've done some searching but I didn't find anything relating to turning the wheel causing excessive pedal travel and decreases braking. Truck is an 89 Xtracab, 4x4 v6 w/ 140000 on the odo. Any help or suggestions would be greatly appreciated

 

It also seems like the steering is pretty hard to turn while the truck is stationary, indicating a possible power steering issue....

 

Those two systems are not closely related. But I would worry that you have a sketchy flexible brake line to the front caliper; it holds when straight but opens a tiny hole when you stretch the line by turning the wheel. This should be very easy to see (brake fluid all over the place),even if the hole is small (the rubber line "damp" with brake fluid).

This doesn't seem likely, but I would check it very quickly. Once you run out of brake fluid you're not stopping, no matter where the wheel is.

 

No issues with any leaking lines, reservoir stays full.... Could this be a vacuum/booster issue since the truck idles down a bit while turning the wheels when stationary?

 

Does your truck have rear wheel ABS??
This ABS system uses the power steering hydraulic system.
Might be an issue with the ABS.

 

Possible front brake flex hose(s) failure

Air in the system.

Leak in hydraulic system.

Master cylinder faulty.

Power steering and brake fluid levels correct..?

 

I don't believe the truck has ABS. I think I am going to take it to a shop and have them do a complete brake system flush and replace all the old fluid in the lines and see if that does the trick. If not I will replace the master cylinder and go from there. It's the original equipment MC so it could probably use replacing anyways. Does my order of troubleshooting sound correct?

 

The flex hoses are good, and plenty of fluid in there....

 

This Toyota truck chronology says rear ABS became standard on trucks as of 1989.

http://www.4x4wire.com/toyota/faq/

 

Only operational in 2wd(2 High) I believe.

 

if it was related to flushing the lines, old fluid etc.. it would be bad all the time. And you sound pretty sure that the fluid level isn't dropping..... Only thing I can think of is what scope mentioned earlier.

 

So if related to power steering pump/rear abs what is the solution?

 

The FSM likely has a troubleshooting/diagnosis order for this system.
I'd look there.

I don't have any ideas other than determining PS pump pressures and output, (you said steering is hard at idle), and ABS parts substitution.

Good luck, and please update as you find your problem.

I don't know anybody who knows very much about this hydraulic ABS system.

 

Does your "rear antilock" light come on when you turn the key on before starting? Does it come on during braking or other operation?

Since you have poor power steering performance, and the rear ABS is operated by the PS pump, I would suspect the two issues are related. I would check for diagnostic codes. These are not the same as the engine control diagnostic codes. The ABS uses a separate ECU and blinks the diag codes out on the rear antilock warning light. The FSM will tell you how to read the codes.

 

Yeah, no rear antilock light...I really don't want to just go start replacing random parts if they don't need it though

 

Do you mean the rear antilock light doesn't exist (meaning you probably don't have rear ABS), or it's there but doesn't light up, meaning the bulb is likely out?

Since you have a 1989, and according to millball's reference the 89's had ABS, you may be just on the cusp of that change. An early '89 might not have it, whereas a late '89 would. It's just that pretty much the most likely thing that would relate brake issues to steering would be that ABS system.

 

The ABS system came only w/SR5 V6 trucks, if I recall. It was not standard in 89 or 90.

I am having a similar problem although not related to turning the wheel but I do believe it has to do w/ABS.

 

an easy way to tell if you have ABS is to look on top of the rear pumpkin, if it has wires going in on top it has a speed sensor and thus, ABS.

 

Just checked the rear end, no wires coming out of the third or housing....back to square one I guess....

 

Just a little more info, when I pull into a parking space while braking, pedal goes to floor....when I stop after pulling in, and i can stop but have very minimal brake pressure, when I come back off the pedal and press it again brake pressure suddenly reappears ....master cylinder seal maybe?