ABS/VSC Nightmare After E-Brake & Brake Booster Replacement

[mrmister]

I love this truck, but it’s been an absolute headache lately.


2001 LX470 with 230,731 miles.

This all started after my parking brake seized (Seattle hills). I replaced the e-brake components, and shortly after that the Zero Point Calibration (ZPC) light came on.

What I’ve done so far:

• I have Techstream, but from what I understand, ZPC can’t be reset on older models through Techstream
• I tried the pin/jumper method multiple times with zero success
• Before the ZPC issue, I started getting VSC lights, which made me suspect a failing master cylinder/brake booster
• I replaced the entire unit with a brand-new OEM Lexus brake booster/master cylinder
• Installed and bled the system using Techstream

Current problems:

• Brake pedal is rock hard
• ABS light ON
• VSC TRAC light ON
• VSC OFF light ON

At this point:

• Truck stops, but braking feels wrong
• I’m worried the ZPC issue may be causing or compounding everything
• I’m out of money and time and need this thing reliable

Questions:

1. Is there a reliable way to reset Zero Point Calibration on an 01 LX470 that actually works?
2. Could a failed yaw rate/decel sensor, wiring issue, or incorrect ZPC be causing:
   • Hard brake pedal
   • ABS/VSC lights after a new booster install?
3. Is there something commonly missed after booster replacement on these trucks?

Any help, write-ups, or “check this before you lose your mind” advice would be hugely appreciated.

Thanks in advance trying hard to keep this LX on the road.

 

[Bisho]

At least for the "rock hard" brake pedal. Make sure your pedal is adjusted to allow the piston to come all the way back. There should be a bit of free play before it pushes the rod. Otherwise the MC doesn't release all the pressure, and it will feel like the brakes are dragging (because they are).

 

[mrmister]

At least for the "rock hard" brake pedal. Make sure your pedal is adjusted to allow the piston to come all the way back. There should be a bit of free play before it pushes the rod. Otherwise the MC doesn't release all the pressure, and it will feel like the brakes are dragging (because they are).

I’ll give that a shot in the morning! Thank you very much!

 

[2001LC]

Likely you un did ZPC. Perhaps you're not correctly resetting ZPC
Go back in tech stream, ABS,
Reset

After above reset.
Go into test mode. This is where it recalibrates.

Notes:
Whenever working on anything with wires attach. Disconnect battery first.
When done flushing and bleeding. Turn IG key off, pump brake pedal 40 times. IG key on, time how long booster motor runs. If 40 second or more with battery at 12.5 volts. Re bleed all 4 corners. In real world, with new master assy. Time will be 28 to 32 sec. at 12.5 volts

 

[2001LC]

I love this truck, but it’s been an absolute headache lately.


2001 LX470 with 230,731 miles.

This all started after my parking brake seized (Seattle hills). I replaced the e-brake components, and shortly after that the Zero Point Calibration (ZPC) light came on.

What I’ve done so far:

• I have Techstream, but from what I understand, ZPC can’t be reset on older models through Techstream
• I tried the pin/jumper method multiple times with zero success
• Before the ZPC issue, I started getting VSC lights, which made me suspect a failing master cylinder/brake booster
• I replaced the entire unit with a brand-new OEM Lexus brake booster/master cylinder
• Installed and bled the system using Techstream

Current problems:

• Brake pedal is rock hard
• ABS light ON
• VSC TRAC light ON
• VSC OFF light ON

At this point:

• Truck stops, but braking feels wrong
• I’m worried the ZPC issue may be causing or compounding everything
• I’m out of money and time and need this thing reliable

Questions:

1. Is there a reliable way to reset Zero Point Calibration on an 01 LX470 that actually works?
2. Could a failed yaw rate/decel sensor, wiring issue, or incorrect ZPC be causing:
   • Hard brake pedal
   • ABS/VSC lights after a new booster install?
3. Is there something commonly missed after booster replacement on these trucks?

Any help, write-ups, or “check this before you lose your mind” advice would be hugely appreciated.

Thanks in advance trying hard to keep this LX on the road.

View attachment 4064837

I'll add. Just getting VSC lights. Doesn't necessarily mean new brake master needed.
Also keep in mind Toyota sets these up. So most any DTC, it will shut down ABS. VSC shuts down (dash off lights on)

 

[mrmister]

Likely you un did ZPC. Perhaps you're not correctly resetting ZPC
Go back in tech stream, ABS,
Reset
View attachment 4065119
After above reset.
Go into test mode. This is where it recalibrates.
View attachment 4065120

View attachment 4065121

Notes:
Whenever working on anything with wires attach. Disconnect battery first.
When done flushing and bleeding. Turn IG key off, pump brake pedal 40 times. IG key on, time how long booster motor runs. If 40 second or more with battery at 12.5 volts. Re bleed all 4 corners. In real world, with new master assy. Time will be 28 to 32 sec. at 12.5 volts

Good Afternoon,

Thank you thank you thank you! So much I figured out my brake connection to the MC the pin wasn’t fully seated and looked like it was .

The ZPC worked flawlessly and now my car is braking fine. And the lights are gone. I really cant thank you enough. Youve saved me close to a divorce. If you got a cashapp or vemmo. Id love to send you some money for a cold one. I greatly appreciate it!

 

[2001LC]

Good Afternoon,

Thank you thank you thank you! So much I figured out my brake connection to the MC the pin wasn’t fully seated and looked like it was .

The ZPC worked flawlessly and now my car is braking fine. And the lights are gone. I really cant thank you enough. Youve saved me close to a divorce. If you got a cashapp or vemmo. Id love to send you some money for a cold one. I greatly appreciate it!

No worries. Glade you got it sorted out!