So I did more test driving and was greeted with a C1029 code. This code come on when one of the brake circuits is lower than the other. I checked on the pressures and LF/RR hit 6k PSI while the RF/LR usually stop at 4k PSI.

If you slowly apply brakes you can sometimes get even pressure and clear the code. The first time I saw it the pedal went to the floor and it felt like I had barely any braking. The vac pump is pumping though so it's not that.

Ford service manual says if the pressures are within 10% then it's the HCU and if they aren't it's the master cylinder. But sometimes I do see equal pressure especially if I use the brakes bake and forth a bunch. The equality is short lived though. I tried to manually bleed the offending circuit to no avail and I even ran the ABS bleed without opening the system. Could it still be air or is either HCU or MS toast?

Can I get away with changing it just using manual bleeding or would it have to be pressure bled?

 

Ok, I got it to go away by bleeding the afflicting side and running the ABS bleed procedure a few times. Now all pressures are in range. Guess it is possible to manual bleed... it will just take you a WHILE.

 

I have a 2011 Mercury Mariner hybrid with the same problem you described in your initial post.... brakes work fine most of the time, but once in a while I get C1029 code.

....so you "manually bleed" the brakes first, (I'm new to hybrids) did you do the "pedal pump method"? Then after that you did ABS bleed ?


Thanks

Bob

 

Yes, pedal pump and then the abs bleed afterwards a few times.

BTW, you can see all 4 pressures and find the offending caliper with forscan.

 

Checked pressures with Forscan and
LF 6K psi. RR 6K psi
RF 5K psi LR 4K psi

so quick question…. When using Forscan to do ABS bleed the program never instructs you to open bleeder screw…. Don’t you need to open the bleeders during this routine?

also ShadyEscape how many times did it take and did you only bleed the RF/LF circuit or did you do all?

thanks for your help

 

I only bled one side where the pressures told me to.

I would manually bleed the affected brakes. Run the ABS bleed 2 or 3 times and then see if I had good pressures. If not I would repeat. It took 5-10 tries. System was closed while doing the service procedure. The goal was to push the air into the brake lines and then push that out manually.