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InteriorZR2
11-11-2006, 08:58 PM
Hey, got the s10 running again today, and no brakes. Tried bleeding them the usuall way, but no help, also tried bleeding the master cylinder but still no help. It a '98 S10 with full size axles. So the abs isnt reallly doing anything, but the abs valve body is still there. Anyone know how to bleed these properly?

crimsen
11-11-2006, 09:07 PM
can't take the abs outta the thing if its not being used ?

sj-x 500
11-11-2006, 10:29 PM
i seem to remember you will have to either vacc bleed it... or disconnect power to the abs ecm?

InteriorZR2
11-12-2006, 03:18 AM
can't take the abs outta the thing if its not being used ?

Yeah, I thought about that, but it looks like every line going into and out of that thing each has a differant size fitting on it. Might come down to that tho. I will try unplugging the ABS ecm today. I pulled the fuse for it, but that didnt seem to help.

Thanks guys.

In The Zone
11-12-2006, 07:56 AM
alot of em u may have to pull the pin on the poprtioning valve to bleed front then rears...

NickB
11-12-2006, 10:46 AM
you have to activate it with a scanner. it toggles all the actuators and let the fluid flow through. Is the only way.

exo_toy
11-12-2006, 10:49 AM
my boss took an ABS course, they said that ABS systems SHOULD BE GRAVITY BLED ONLY! Once you get air in the ABS unit, it can be impossible to get out.

I did bleed my 97 sonoma the usual way (pumping the brakes and so on) before I knew this information, and it worked. Just got lucky I guess.

Sometimes the ABS unit will have a bleeder on it. Maybe call the GM dealership and talk to one of the techs and see what they do.

InteriorZR2
11-12-2006, 11:27 AM
Looks like I am going to be figuring out some way to get rid of the whole abs unit. Does anyone know which port on the MC is for the rear, and which is for the front? My first guess would be front is front, and closest to firewall would be rear, but I could be wrong?

Jroc
11-12-2006, 09:54 PM
fixed!!! just remember next time L means left!

Spooner
11-14-2006, 06:51 PM
I go to this from a Blazer forum. Most of the guys on there know there shit for the most part. This might help





ABS BLEEDING PROCEDURE
NOTE: Bleeding ABS system requires the use of Tech 2 scan tool. An
assistant is required when performing bleeding procedures.
1) Raise and support vehicle. Begin bleeding at right rear
wheel. Install a clear plastic hose to bleed screw. Immerse other end
of hose in container that is partially filled with clean brake fluid.
2) Open bleed screw 1/2 to 1 full turn. Have assistant slowly
depress brake pedal until it reaches full travel. Hold pedal until
bleed screw is closed. Release brake pedal and wait 10-15 seconds.
Repeat until clean bubble-free brake fluid is present at wheel bleed
screw.
3) Check master cylinder fluid level every 4-6 strokes of
brake pedal to avoid running system dry. Repeat steps 2) and 3) on
left rear, then right front, then left front. After bleeding all 4
wheels, go to next step.
4) Using scan tool in FUNCTION TEST, run FUNCTION TEST 4
times consecutively while applying the brake pedal firmly. Release
brake pedal between each test.
5) Rebleed all 4 wheels to remove remaining air from brake
system. Ensure brake pedal feel is appropriate before attempting to
drive vehicle. Rebleed as many times as necessary to obtain
appropriate pedal feel.
DIAGNOSIS & TESTING
NOTE: When testing and diagnosing 4WAL system, use of Tech 2 scan
tool is required.
The Electronic Brake Control Module (EBCM) performs a selfdiagnosis
of the ABS system. The EBCM detects and isolated system
failures, then sets the corresponding diagnostic trouble code (DTC).
Before diagnosing 4WAL system, perform a comprehensive visual
inspection of system by checking wiring harness connectors, harness
routing (pay particular attention to wheel speed sensor wiring harness
routing), applicable fuses in fuse block, and ground connections.
Ensure brake fluid level in master cylinder reservoir is full.
Start 4WAL system diagnosis using DIAGNOSTIC SYSTEM CHECK. If
failures are found when performing diagnostic system check, you will
be directed to enter diagnostics to retrieve DTCs or perform SYMPTOM
TESTS. Diagnostic system check may indicate that system is functioning
properly.
RETRIEVING DTCS
Connect Tech 2 scan tool to DLC located under steering
column. Access 4WAL brake DTCs. Repair DTCs in the order they appear.
See 4WAL DIAGNOSTIC TROUBLE CODE (DTC) table for diagnosis. Before
diagnosing DTC(s), perform DIAGNOSTIC SYSTEM CHECK.
4WAL DIAGNOSTIC TROUBLE CODE

InteriorZR2
11-14-2006, 07:15 PM
Holly crap, that is a lot of sheit to do just to bleed the brakes. We ended up just ripping out the ABS ecm and teeing the lines into the MC. After a lot of f'n around, and enough brake fluid to stop dehydration in the sahara, we got er going...... who knew that something could have been so simple.... next time I will make sure I put the proper caliper on the right side of the truck.... Couldnt figure out why brakes felt good after we bled the rear, and as soon as we touched the fronts, everything whent for a crap again... Anyways, now I know. Thanks Jroc.