Help! Stuck mid hub assembly removal on an 06 prius

If you post your location then maybe there are fellow PriusChatters in your area that can help with reading DTCs. (I recently had some luck talking to the skid control ECU but we are probably not in the same region.)

 

This is in the manual. If you can measure the voltage on the correct ECU pin you can do this without the Intelligent tester.

Skid control ECU
OK:
Accumulator pressure sensor voltage does not
drop.
NG
DTC C1391/69 Accumulator Leak Malfunction
DTC No. INF Code DTC Detection Condition Trouble Area
C1391/69 591 Accumulation performance is
deteriorated (improper sealing
inside the actuator, gas pressure
drop inside the accumulator, leak
in each pressure boosting valve).
• Fluid leakage
• Brake actuator assembly
1 CHECK BRAKE FLUID LEAKAGE
REPAIR OR REPLACE APPLICABLE PART
2 READ VALUE OF INTELLIGENT TESTER (ACCUMULATOR PRESSURE SENSOR)
Item Measurement Item / Range
(Display)
Normal Condition Diagnostic Note
ACC PRESS SENS 1 Accumulator pressure sensor 1 /
Min.: 0 V, Max.: 5 V
Specified value: 3.2 to 4.0 V -
REPLACE BRAKE ACTUATOR ASSEMBLY

Also did you pull the relays and forget to replace them?
C1242/42 87 Voltage is applied to IG2 terminal,
but not applied to IG1 terminal for
at least 4 sec.
• ABS NO. 1 relay
• Harness and connector
• Skid control power supply
circuit
• Brake control power supply
assembly
• Hybrid control system
BC–88 BRAKE CONTROL – ELECTRONICALLY CONTROLLED BRAKE SYSTEM
BC
C1242/42 88 Voltage is applied to IG1 terminal,
but not applied to IG2 terminal for
at least 4 sec.
• ABS NO. 2 relay
• Harness and connector
• Skid control power supply
circuit
• Brake control power supply
assembly
• Hybrid control system

 

I'll throw my 2 cents in, even though this post is old. I have been advised to NEVER press the brake piston back in without opening the bleed valve on a car with ABS. There are sensitive valves in the system that can get damaged by forcing the fluid backwards by pressing in the piston. On the Axle nut - I removed mine, tried to get the bad hub out, couldn't, torqued the nut back on, re-pined it, then a couple of weeks later took it all apart again and had a shop remove the old hub from the knuckle. Here's the rub - when I torqued down the nut 159 ft-lb, it apparently 'stretched' the axle threads. When I removed it the second time, even though I drove out the pined section, it trashed the axle threads. I knew I was in for trouble when it took a 24" breaker bar to remove the nut all the way off the axle. And, for what it's worth, a re-manufactured axle at NAPA was 61 with a 50 core charge. Somehow, my speed sensor is malfunctioning. When I exceed 60 mph, I get VSC/ABS warning lights and the regen brakes are not working correctly, and mileage dropped about 5 mpg. A new sensor from the dealership is about 250.00, from Rock Auto about 98. I still wonder if the tone ring on the new axle is not up to snuff and actually the problem. We'll see once I replace the sensor. I tried the paper clip reset method but the error keeps coming back.

 

In any car with or without ABS there must be a reasonable free flow of fluid back to the brake reservoir from the cylinders. If this were not the case the brakes once applied would stay on. Further the Prius hydraulic system is not like that of other cars. Opening a bleed valve to do as you suggest will produce a DTC code, and the brakes will not work correctly if at all.

John (Britprius)

 

Johnny-
I agree with you but routinely see posts here where people pushed the caliper piston back in on this car with a c clamp. Without opening anything. The fluid must be pushed back through the actuator valve. I would think the valve would not like it.

I think where you went wrong is you did not disconnect the 12 volt battery. And then push the brake pedal a few times to dissipate the back up 12 volt cap assy before you even touched the brakes. If the 12 volt is still connected sometimes just opening the door will cause the actuator to fire and it will push a piston out a little and set that dtc. Those dtc's are safety related and must be cleared by Techstream or VCI software. Disconnecting the battery will not erase them.

And axle nuts should routinely be replaced once used. Given the very high torque value they are tightened too there already distorted once tightened and then removed. This distortion cannot be seen with the naked eye. But trust me its stretched. Re-using that nut is putting back a distorted nut at again very high torque. Hilarity usually ensues.
Always replace the axle nut.

 

There is something about the valves in certain ABS systems that makes them sensitive. I don't know if Toyotas are like this, but I take a short piece of a 2x4, put it in the caliper, and use a couple of short bungees to hold it in place and hang it from the strut spring. Absolutely replace the axle nut! I just bought one from the dealer this week in preparation for replacing my right front hub. It only cost me $8. And, as advised by trained mechanics (not dealership ones) always drive the pined section out before removing the nut or it could ruin the axle threads. The dealer showed me the special punch that they use for this (very expensive). I just bought a narrow chisel and took it to a grinder to make it narrow enough to slide into the channel. I know the nut is softer than the shaft, but I made the mistake of reusing a nut, which stretched when I torqued it down, and when I removed it the second time, it ruined the axle threads. The mechanic that pressed the hub out of the knuckle for me yesterday told me that many of the newer axles are not as hard or high quality as they used to be. They have had threads ruined on new cars that had never been touched before, and they do know what they are doing. They just don't make them like they used to - as in Timkin bearings, some are now made in China!