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ABS

50K views 25 replies 9 participants last post by  jl8088 
#1 ·
Is there a write up anywhere on how to bleed the brakes? I cant seam to find a reason my ABS light is on and I have checked the sensors are intact at each wheel. Nothing looks broken. Maybe some air is trapped somewhere>?
 
#3 ·
Service and Repair

Bleeding Brake Hydraulic System
A bleeding operation is necessary to remove air from the hydraulic brake system whenever air is introduced into the hydraulic system. It may be necessary to bleed the hydraulic system at all four brakes if air has been introduced through a low fluid level or by disconnecting brake pipes at the master cylinder. If a brake pipe is disconnected at one wheel, only that wheel cylinder/caliper needs to be bled. If the pipes are disconnected at any fitting located between the master cylinder and brakes, then the brake system served by the disconnected pipe must be bled.

For 4-Wheel Antilock Brake System (ABS) equipped vehicle, be sure to remove the ABS main fuse 60A located at the relay and fuse box before bleeding air. If you attempt to bleed air without removing the main fuse, air cannot be let out thoroughly, and this may cause damage to the hydraulic unit. After bleeding air, be sure to replace the ABS main fuse back to its original position.
Set the parking brake completely, then start the engine. Note: The vacuum booster will be damaged if the bleeding operation is performed with the engine off.
Remove the master cylinder reservoir cap.
Fill the master cylinder reservoir with brake fluid. Keep the reservoir at least half full during the air bleeding operation
Always use new brake fluid for replenishment.
In replenishing brake fluid reservoir, carefully pour the brake fluid to prevent air bubbles from entering the brake system When the master cylinder is replaced or overhauled, first bleed the air from the master cylinder, then from each wheel cylinder and caliper following the procedures described below. Bleeding the Master Cylinder
Disconnect the rear wheel brake pipe (1) from the master cylinder. Check the fluid level and replenish as necessary. If replenished, leave the system for at least one minute.
Depress the brake pedal slowly once and hold it depressed.
Completely seal the delivery port of the master cylinder with your finger, where the pipe was disconnected then release the brake pedal slowly.
Release your finger from the delivery port when the brake pedal returns completely.
Repeat steps 8 through 10 until the brake fluid comes out of the delivery port during step 8. Note: Do not allow the fluid level in the reservoir to go below the half-way mark.
Reconnect the brake pipe (1) to the master cylinder and tighten the pipe.
Depress the brake pedal slowly once and hold it depressed.
Loosen the rear wheel brake pipe (1) at the master cylinder.
Retighten the brake pipe, then release the brake pedal slowly.

Repeat steps 13 through 15 until no air comes out of the port when the brake pipe is loosened Note: Be very careful not to allow the brake fluid to come in contact with painted surfaces.
Bleed the air from the front wheel brake pipe connection (2) by repeating steps 7 through 16. Bleeding the Caliper
Bleed the air from each wheel in the order listed below:
Right rear caliper or wheel cylinder
Left rear caliper or wheel cylinder
Right front caliper
Left front caliper Conduct air bleeding from the wheels in the above order. If no brake fluid comes out, it suggests that air is mixed in the master cylinder. In this case, bleed air from the master cylinder. In this case, bleed air from the master cylinder in accordance with steps 7 through 17, and then bleed air from the caliper or wheel cylinder.
Place the proper size box end wrench over the bleeder screw.
Cover the bleeder screw with a transparent tube, and submerge the free end of the transparent tube in a transparent container containing brake fluid.
Pump the brake pedal slowly three (3) times (once/sec), then hold it depressed.
Loosen the bleeder screw until fluid flows through the tube.
Retighten the bleeder screw.
Release the brake pedal slowly.
Repeat steps 21 through 24 until the air is completely removed. It may be necessary to repeat the bleeding procedure 10 or more times for front wheels and 15 or more times for rear wheels.
Go to the next wheel in the sequence after each wheel is bled. Be sure to monitor reservoir fluid level.
Depress the brake pedal to check if you feel "sponginess" after the air has been removed from all wheel cylinders and calipers. If the pedal feels "spongy", the entire bleeding procedure must be repeated.
After the bleeding operation is completed on the each individual wheel, check the level of the brake fluid in the reservoir and replenish up to the "MAX" level as necessary.
Attach the reservoir cap. If the diaphragm inside the cap is deformed, reform it and install.
Stop the engine.
 
#5 ·
Also I just read this.. Is there a way to TEST the EBCM? This description sounds like what my problem is. When the light turns off occaisonally it will apply the ABS feature everytime I hit the breaks. Then the light comes on and it disables the ABS..

An occasional problem on this vehicle is failure the Electronic Brake Control Module (EBCM) for the Antilock Brake System (ABS). Failure of the EBCM can cause the ABS hydraulic pump to run continuously, or cause the ABS light to illuminate. The cost to replace the EBCM is $278.92 for parts and $65.00 for labor. All prices are estimates based on $65.00 per flat rate hour and do not include diagnostic time or any applicable sales tax.
 
#8 ·
Not sure if the unit is the same on the 98 as on the 2001. Information from alldata seems pretty scant other than the component location. It says basically test as you would other electronic components.

let me know what specifics you need and I will post them for you if I can.
 
#9 ·
Well, My current task is trying to find out how to jump the diagnostics center to read the codes. I dont have a dealership closeby that I know of. I need to pull the ABS codes withought a scanner. Noone around here has a scanner either for sale/or use. I really would rather not buy one tho.

Anyways - I know there is a way to jump it with a paperclip and get the ABS light to give you the reading by a series of flashes but I dont know what that procedure is. (Its different on every Make/Model)
 
#15 ·
pktrusty said:
Does the ABS have its own OBD II port?
Nope - Its the same OBDII port that you hook a regular Scan tool to - instead of hooking up a scan tool you just jump the two ports.

There is also a way to pull OBDII codes but I cant remember which two to jump. I seam to think it was 10/Gnd but cant remember. In any case for OBDII codes its the CEL that blinks. For DTC codes its the ABS light that flashes
 
#16 ·
My ABS light is on and my OBD scanner is not picking anything up. By jumping the two terminals listed earlier, I will be able to check the errors in my ABS system via flashes? Ah, I am getting flashbacks of my 2.8L with the connector under the center console.
 
#19 ·
You have to do the jumper to get ABS codes. Its NOT the same reader as an OBDII reader and NO autozone will not read ABS codes. They told me to go to a dealer cause the dealer is the only one with an ABS scanner.

Anyways - the codes are seprated guys. Its 2 completely different test. OBDII codes are different than ABS Codes.
 
#21 ·
surjer said:
pktrusty said:
Does the ABS have its own OBD II port?
Nope - Its the same OBDII port that you hook a regular Scan tool to - instead of hooking up a scan tool you just jump the two ports.

There is also a way to pull OBDII codes but I cant remember which two to jump. I seam to think it was 10/Gnd but cant remember. In any case for OBDII codes its the CEL that blinks. For DTC codes its the ABS light that flashes
Hi,

I used a piece of paper clip to jump the 4 to 12 terminals as described on this forum. The ABS light did not blink, only the air bag light and it only blinked the 1 -2 signal. My ABS on my 2000 Trooper does not seem to be working when I brake hard on a dirt/gravel road. Can anyone tell me how to read my ABS codes?

Thanks, Steve
 
#22 ·
Just got the valve cover gasket change, one of the bolts of the valve cover near the brake master cylinder was difficult to remove, so the mechanic at a independent shop removed the brake master cylinder and did the valve cover gasket change, replaced the master cylinder then bleeded the brakes at all the four wheels, this without removing the ABS main fuse and yes while the engine is running. once in a while the ABS light comes off till the next start cycle. Is there a electrical connection I have to check or there is some internal damage to the ABS system or there is still some air in the brake system which is causing the intermittent ABS light.

Any help is appreciated , the 1998 V6, 2WD, Auto, front disk, rear drum has 125K miles and running strong.
 
#23 ·
bahmed said:
Just got the valve cover gasket change, one of the bolts of the valve cover near the brake master cylinder was difficult to remove, so the mechanic at a independent shop removed the brake master cylinder and did the valve cover gasket change, replaced the master cylinder then bleeded the brakes at all the four wheels, this without removing the ABS main fuse and yes while the engine is running. once in a while the ABS light comes off till the next start cycle. Is there a electrical connection I have to check or there is some internal damage to the ABS system or there is still some air in the brake system which is causing the intermittent ABS light.

Any help is appreciated , the 1998 V6, 2WD, Auto, front disk, rear drum has 125K miles and running strong.
Got the following ABS Codes in the order C0265, C0277, C0251, C0246, C0245, C0241, C0242, C0252, these were the 8 codes in the order, i recently had the alternator replaced, C0277 is low ignition voltage, C0252 is Rear Open dump solenoid, the power to the fuse box from the battery has a raw joint like twisted wire joint with electrical tape on it, is this the reason i have damaged EBCM or something else. Any help is appreciated.
 
#24 ·
Problem solved, after doing some reasearch, found the Electronic Brake Control Module (EBCM) part no: 8-97357-701-0, GM# 97357701 from ebay for $82 incl shipping, part condition was New. Attached is the combined photo (Left is New, right is old) as well as a photo of the ABS unit with the EBCM removed. I was getting ABS light after the roadside mechanic bleeded the brakes WITHOUT removing the ABS Fuse (60A). Never bleed the brakes without removing the ABS fuse first. If you have this kind of issue, google for absfixer.com or airbags.com, you can remove the EBCM and send to one of these firms they fix the unit and send it back in 24hrs as per their website. I would have used one of them had I not found the brand new unit on ebay for a good price. Also, it is a simple plug and play, no programming is required what so ever. Hope this information help the Isuzu owners.
 

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#25 ·
I did this job last Friday. Only took about 30 min to replace just the EBCM. I had to order the entire ABS Module from an online junk yard. It was for a '98 but it is the same as on my 2000 Trooper. They wanted $260 for the part and I told them the most I would pay was $150. I got it for that plus shipping, $20.

Worked like a champ! ABS light is out and no codes!

Sunday I went to a Pick-A-Part junk yard for some odds and ends and there were at least 6 EBCMs that would have fit the 2000 Trooper! Oh well, too late too smart. I bet I could have got one for $20! Lots of other great parts! I'm going back!
 
#26 ·
I bled my brakes without removing the abs fuse.
I did not have the engine running when bleeding the brakes.
After bleeding and starting the 1999 trooper up, the brake light on the dash came on and would intermittently come on and/or go away.
I ordered a junkyard ebcm module from another 4x4 trooper and just replaced my original
This was 6 torx screws and 2 connectors (difficult access, removed battery and moved windshield washer hose)
There was this spring type metal thing sandwiched between module and pump that I reused?
After putting everything back together I still have the brake light on the dash and now the abs light is on.

Any ideas on what to try next?
 
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