Question about 1999 Chevrolet Silverado 1500

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Abs hydraulic unit chevy truck

I replaced all the lines on the hcu i cant get sys to bleed i don't know if i got one of the lines crossed. i put master cyl front in top left of hcu master cyl right then rear on the bottom i put right front then left front and i can't get it to bleed.do i have a line crossed?

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  • Chevrolet Master
  • 1,129 Answers

The ABS unit should have the connection IDs embossed into the casting at every line connection.You are going to HAVE TO determine every connection line going to every component to make this work.

Posted on Mar 21, 2018

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6ya staff

  • 2 Answers

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Posted on Jan 02, 2017

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airjoc

Rob Sinbad

  • 709 Answers

SOURCE: 1994 Cavalier -replaced master cylinder-no pressure to rear brake

The most common bleeding procedure is to bleed the ABS brake furthest from the master cylinder first, then bleed the other brake that shares the same hydraulic circuit (which may be the other rear brake on a rear-wheel drive car, or the opposite front brake on a front-wheel drive car or minivan). After these have been bled, you then bleed the other brake circuit starting with the furthest brake from the master cylinder.
Air can be very difficult to remove from an ABS modulator assembly because of all the nooks and crannies inside the unit. The modulator may have eight to 10, or more, ABS/traction control solenoid valves, plus various check valves and dead-end ports. Some ABS modulators have special bleed screws to help you vent the trapped air when bleeding the system. Others do not and require the use of a scan tool to cycle the ABS solenoids while you bleed the system. 1. To bleed the isolation valves in the modulator, there are two bleeder screws. Start with the one toward the engine. Turn the ignition on and apply light pressure on the brake pedal. Open the bleeder screw and allow the fluid to flow until clear. Close the screw and do the same at the second bleeder screw. 2. Depressurize the accumulator by pumping the pedal 40 times with the key off. Wait about two minutes for the brake fluid to de-aerate, then refill the fluid reservoir with DOT 3 brake fluid. 3. Now you can bleed the boost section. This is done by applying moderate pressure on the brake pedal and turning the ignition on for three seconds, then off. Repeat this a total of 10 times. Make sure the pedal feels firm when you have finished, and give the car a road test to make sure the brakes are working properly.

Posted on Jul 25, 2009

Auto Master

Roy Funkhouser

  • 140 Answers

SOURCE: 00 Chevy Silverado... ABS EBCM diagram help??? Brake line hookups

Hello,
I hope this helps.






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Thank You,
Roy

Posted on Aug 28, 2009

Anonymous

  • 158 Answers

SOURCE: 00 Chevy EHCU HELP

bleed each separately

Posted on Aug 29, 2009

inspectmycar

Chris Biddle

  • 233 Answers

SOURCE: how do you bleed the abs unit on a 1997 chevrolet truck

start by bleeding the master cylinder bleed the line closest to the fire wall, then proceed to the right rear wheel, left rear wheel, right front wheel, and then the left front wheel.

Posted on Sep 16, 2009

Mike

  • 4367 Answers

SOURCE: bleeding brakes 2000 suburban wsith ab

Why were the brake lines replaced?

Sounds like the mastercylinder may have run dry. You have to bench bleed the master and then DO NOT allow fluid to run low, while bleeding brakes...

if master cylinder runs low on fluid and air gets in, almost impossible to bleed with out releasing the lines and bleed master it self.

Posted on Sep 20, 2009

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1 Answer

Abs hydraulic unit chevy truck


some vehicle made by GM require special sequence bleeding and a scan tool to open the abs brake module to bleed all the air

Jan 08, 2018 | Cars & Trucks

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1994 buick lesabre new master cylinder abs light on


Look for a bleeder on ABS HCU unit- the one with brake tubing

Drive it & then Bleed again

Have to hear the abs pump come on,check fuse for it

If that doesn't work may have to open the
hcu with an obd1 scan tool & bleed

Feb 01, 2013 | 1994 Buick LeSabre

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Back brake won't brake or bleed


Check for loss of fluid pressure to the brake caliper due to a damaged brake hydraulic line or a defective ABS hydraulic control unit. This really requires a professional to diagnose.

Oct 11, 2012 | Cars & Trucks

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Where is the abs pump in a 2000 galant


Galant and Mirage


0900c152800383f6.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig. HCU mounting-Mirage


0900c152800383f7.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig. HCU mounting-Galant

  1. Use a syringe or similar device to remove as much fluid as possible from the reservoir. Some fluid will be spilled from lines during removal of the hydraulic unit; protect adjacent painted surfaces.


CAUTION Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with the eyes and wash your hands thoroughly after handling brake fluid. If you do get brake fluid in your eyes, flush your eyes with clean, running water for 15 minutes. If eye irritation persists, or if you have taken brake fluid internally, IMMEDIATELY seek medical assistance.
  1. Remove the splash shield from the left front wheel house or fender area.
  2. Remove the coolant reserve tank.
  3. Remove the coolant reservoir bracket.
  4. Remove the dust shield from below the hydraulic unit.
  5. Disconnect the brake hoses and lines from the hydraulic unit. Correct reassembly is critical. Label or identify the lines before removal. Plug each line and each port immediately after removal.
  6. Remove the cover from the relay box. Disconnect the electrical harness to the hydraulic unit.
  7. Remove the bolts holding the 3 mounting brackets to the vehicle; remove the unit downward and out of the vehicle.


NOTE The hydraulic unit is heavy; use care when removing it. The unit must remain in the upright position at all times and be protected from impact and shock.
  1. Set the unit upright, supported by blocks on the workbench. The hydraulic unit must not be tilted or turned upside down. No component of the hydraulic unit should be loosened or disassembled.
  2. The brackets and relays may be removed if desired.

To install:
  1. Install the brackets and relays if they were removed. Tighten the bracket bolts to 16 ft. lbs. (22 Nm).
  2. Install the hydraulic unit into the vehicle, keeping it upright at all times.
  3. Install the retaining bolts holding the brackets to the vehicle. Tighten the bolts to 16 ft. lbs. (22 Nm).
  4. Connect the hydraulic unit wiring harness.
  5. Install the cover on the relay box.
  6. Connect each brake line loosely to the correct port and double check the placement. Tighten each line to 10 ft. lbs. (13 Nm).
  7. Fill the reservoir to the MAX line with brake fluid.
  8. Bleed the brake system.
  9. Install the dust shield and the coolant reserve tank with its bracket.
  10. Install the fender splash shield.
  11. Check ABS system function by turning the ignition ON and observing the dashboard warning lamp. Test drive the vehicle and confirm system operation

Jun 09, 2012 | 2000 Mitsubishi Galant

1 Answer

Still cant get a brake pedal.. been bleeding the lines but not getting much out of them. replaced master cylinder, still no pedal. has all new lines also


you may have to run the motor as you bleed the brakes so the abs hydraulic unit can purge any air that might be caught within the unit itself.did you bench bleed the master cylinder before installing it on the car.this can save time and reduce the possible chance of air entering the system.make sure you don`t allow the master cylinder to run low on brake fluid.i also assume that you are bleeding the brakes properly.Left front brake works with Right rear brake and Right front brake works with Left rear brake.this is how the brakes should be bleed.

Mar 15, 2011 | 1997 Buick LeSabre

1 Answer

How do to replace the abs control module?


If you are talking about just replacing the electronic ABS module (EBCM), it simply unplugs and unscrews from the hydraulic control unit. If you are talking about replacing the hydraulic control unit (HCU) then you must disconnect the EBCM. Disconnect all of the brake lines from the HCU. Remove the mounting bolts from the HCU and remove HCU from vehicle. Then you reverse th order to reinstall. Once it is installed you must use a scan tool to perform automated bleeding to get all the air out of the hydraulic unit and the rest of the brake system.

Feb 21, 2011 | 2006 Chevrolet Trailblazer

1 Answer

How to bleed the brakes


Bleeding the ABS System

Print


NOTE
This procedure requires the use of a scan tool.


NOTE
Performing the SYSTEM BLEED FUNCTION on the diagnostic tool drives trapped air from the hydraulic control unit (HCU). Subsequent bleeding removes the air from the brake hydraulic system to the bleeder screws.


NOTE
The engine must be running to provide adequate voltage to the HCU module during the anti-lock control portion of the system bleed.

1. Connect the diagnostic tool.

2. Start the engine and depress the brake pedal to half of the full travel position.

3. Access FUNCTION TEST mode and press the trigger to run the SYSTEM BLEED FUNCTION.

4. Manually bleed the brake hydraulic system.

5. Repeat the procedure performing a total of two diagnostic tool cycles and two manual bleed cycles. The bleed procedure is complete.


Hope helps.

Nov 01, 2010 | Ford Laser Cars & Trucks

2 Answers

I replaced the brake master cylinder on my 91 Lincoln Mark 7 with a non high pressure master cylinder and the rear brakes do not hold. Do I need to change the cal. on the rear also?


ANTI-LOCK BRAKE SYSTEM (and HCU-Hydraulic Control Unit)
General Information The 4-Wheel Anti-lock Brake System (ABS) is an electronically operated, all wheel brake control system. Major components include the power brake booster, master cylinder, the wheel speed sensors, and the Hydraulic Control Unit (HCU) which contains the control module, a relay, and the pressure control valves. The system is designed to ****** wheel lockup during periods of high wheel slip when braking. Retarding wheel lockup is accomplished by modulating fluid pressure to the wheel brake units. When the control module detects a variation in voltage across the wheel speed sensors, the ABS is activated. The control module opens and closes various valves located inside the HCU. These valves, called dump and isolation valves, modulate the hydraulic pressure to the wheels by applying and venting the pressure to the brake fluid circuits. Some models are equipped with a Traction Assist (TA) system. The TA system senses wheel spin upon acceleration, turns on the Hydraulic Control Unit (HCU) pump and applies fluid pressure to the appropriate rear wheel. Two additional isolation valves in the HCU will also close to permit fluid to flow only to the rear wheels. The TA system monitors TA usage to avoid overheating the rear brakes. If the system does sense brake overheating, the ABS module will inhibit TA operation until the rear brakes are permitted to cool down.
---
SYSTEM COMPONENTS The anti-lock brake system consists of the following components:
  • Vacuum booster and master cylinder assembly
  • Hydraulic Control Unit (HCU)
  • ABS module
  • Wheel sensors
  • Pedal travel switch
---
On 1992-1994 and 1995-00 a scanner is used to perform the brake bleed. But on yours, I think it's different according to the manual.
---
What do you mean change the cal. on the rear also? Do you mean Caliper?

Jul 26, 2010 | 1991 Lincoln Mark VII

1 Answer

I have a 2001 gmc sonoma 4.3 replace brake lines on back i am not getting any fluid to rear wheels i tryed bleeding sys with help diconected abs sys to reset to defalt no abs light is on stumped


a special tool is required to hold the ABS hydraulic control unit popit valves open during bleeding of the brakes, without this special tool you will not be able to get the air out of the system, most good brake shops have this tool or of course the local Chevy dealer or GMC dealer. I am a dealer tech and know this information is correct..

May 12, 2010 | 2001 GMC Sonoma Extended Cab

1 Answer

Brakes won't bleed!


the brake system on these units cant be bled at home if air gets into themaster cylinder and or the (hcu) hydraulic control unit,a special anti-lock brake test adapter has to be pluged into the control module, any atempt to bleed the system with out this tool wiil result in a spongy pedal

Jul 02, 2009 | 1998 Ford Expedition

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