Need help diagnosing abs codes 2002 4runner

[sile7vt]

2002 Toyota 4runner

Traction control, abs, and break warning light are on, audible brake warning noise, brake pedal is locked up with maybe an inch of play, but wheels still move so brakes aren't completely locked.

VCS light is NOT on and no check engine light.

Abs fuses all look fine, and I can hear an audible clicking coming from the relay housing that holds the abs sol, trc mtr, and abs mtr relays.

Here's the codes I was able to pull from my abs system

C0279 TOYOTA Code - Short to B+ in ABS Solenoid Relay Circuit
C0278 TOYOTA Code - Open or Short Circuit in ABS Solenoid Relay Circuit
C1223 TOYOTA Code - ABS Control System Malfunction

Now as far as i can tell from my research c1223 is just a general abs malfunction code so c0279 and c0278 are the important ones.

I found this article that explains the conditions needed to trip both of those codes

Toyota 4Runner: Open in ABS Solenoid Relay Circuit (C0278,C0279) - Vehicle Stability Control System(for Hydraulic Brake Booster) - Service Manual

I don't know enough about this stuff to really make sense of what exactly that article is telling me. I was able to find a writeup online that said 278 means that the computer did not see power across the abs sol relay, cant really find anything about 279.

Been seeing a lot of stuff about it potentially being a faulty abs control module but that is usually also accompanied by the VSC light which I don't have lit up.

The only other thing I can see online besides it being either the relays or ya know the $1500 dollar one is the ABS TRAC Skid Control Relay, which i for the life of me cannot find any pictures or diagrams online as to where in the hell that thing is located.

So all that being said, any help breaking down what that article is telling me, or any suggestions on where to start/investigate would be really appreciated. Kinda just shooting shots in the dark trying to avoid a $1500 part.

 

[spartacus]

2002 Toyota 4runner

Traction control, abs, and break warning light are on, audible brake warning noise, brake pedal is locked up with maybe an inch of play, but wheels still move so brakes aren't completely locked.

VCS light is NOT on and no check engine light.

Abs fuses all look fine, and I can hear an audible clicking coming from the relay housing that holds the abs sol, trc mtr, and abs mtr relays.

Here's the codes I was able to pull from my abs system

C0279 TOYOTA Code - Short to B+ in ABS Solenoid Relay Circuit
C0278 TOYOTA Code - Open or Short Circuit in ABS Solenoid Relay Circuit
C1223 TOYOTA Code - ABS Control System Malfunction

Now as far as i can tell from my research c1223 is just a general abs malfunction code so c0279 and c0278 are the important ones.

I found this article that explains the conditions needed to trip both of those codes

Toyota 4Runner: Open in ABS Solenoid Relay Circuit (C0278,C0279) - Vehicle Stability Control System(for Hydraulic Brake Booster) - Service Manual

I don't know enough about this stuff to really make sense of what exactly that article is telling me. I was able to find a writeup online that said 278 means that the computer did not see power across the abs sol relay, cant really find anything about 279.

Been seeing a lot of stuff about it potentially being a faulty abs control module but that is usually also accompanied by the VSC light which I don't have lit up.

The only other thing I can see online besides it being either the relays or ya know the $1500 dollar one is the ABS TRAC Skid Control Relay, which i for the life of me cannot find any pictures or diagrams online as to where in the hell that thing is located.

So all that being said, any help breaking down what that article is telling me, or any suggestions on where to start/investigate would be really appreciated. Kinda just shooting shots in the dark trying to avoid a $1500 part.

Those c0278-c0279 are caused by the abs relay or circuit. The abs relay is located on the passenger fender in the engine bay.

 

[sile7vt]

Those c0278-c0279 are caused by the abs relay or circuit. The abs relay is located on the passenger fender in the engine bay.

Yeah so the relays as far as I can tell are working. I can here them clicking on and off again as the computer keeps trying again and again to read power from whatever abs system isnt recieving it. Fuses connected to it are fine as well. I think the key thing here is that the fluid is rising all the way to the top of the system. To the point where the pedal cant be pressed at all because its back pressured, and simultaniously theres no pressure on the brakes because theres no fluid in the calipers, its all moved to the top of the resevoir. Its almost like the booster is working backwards

 

[96RedRunner]

Trac control module is under dash above your left foot when sitting in seat. Codes you have are not pointing to that module. Can be had for $400 used.
What your describing sounds as your MC rubber internals have worn out and are bypassing causing Rez to backfill.
Had similar conditions on my 01 last August.

 

[spartacus]

Trac control module is under dash above your left foot when sitting in seat. Codes you have are not pointing to that module. Can be had for $400 used.
What your describing sounds as your MC rubber internals have worn out and are bypassing causing Rez to backfill.
Had similar conditions on my 01 last August.

Not my issue just trying to help out OP
Did you buy a used, new master or rebuild it?. I have read threads that mention a guy on Edmunds rebuilding these. Do you know if the 2003-4 rebuilt kit will work with 2001-2002? AFAIK there isn't one specific to 01-02.

 

[96RedRunner]

[MENTION=50279]spartacus[/MENTION], Same here responding to OP. Got a new one buy once cry once, I'm good for 200k mi.
I looked at all the pieces that make up the MC a rebuild doesn't cover critical parts PCB and Accumulator.
I dug some into rebuilding not enough to pass any info on, will know more when I tear down the old one.
My case the pump motor brushes wore down too far, hit it with hammer got it to run couple times, reman motor/pump $400 3 yrs. ago.
Started putting money back 4 yrs. to cover a new one.