[4th Gen : 01-07]: Bleeding brakes with ABS
#1
10-25-2014, 12:29 PM
Bleeding brakes with ABS
I (having had to replace a brake line) had to remove and reinstall the ABS in my 02 Grand Caravan.
During this process an unknown quantity of fluid escaped from the ABS unit, so it MAY need to be bled. (I think it was only a small amount, but am not really sure.) The procedure below says I need to bleed the ABS system; however it requires a DBSIII, I do not have one, none of my local part stores has one for loan, and I have heard that they cost $1,500.
So, my questions for you experts are:
1. referring to the procedure below, if I just bleed the standard base system, and there IS air in the ABS, what will happen when I start and drive the vehicle?
- will I get a check engine light or other diagnostic warning on the dashboard?
- will the pedal be spongy?
2. If the pedal is not spongy and the brakes seem to be operating normally can I assume everything is okay and the ABS system does not need to be bled?
This procedure is from the service manual for my 02 Grand Caravan:
STANDARD PROCEDURE - ANTILOCK BRAKE SYSTEM BLEEDING
The base brake’s hydraulic system must be bled anytime air enters the hydraulic system. The ABS though, particularly the ICU (HCU), should only be bled when the HCU is replaced or removed from the vehicle. The ABS must always be bled anytime it is suspected that the HCU has ingested air. Under most circumstances that require the bleeding of the brakes hydraulic system, only the base brake hydraulic system needs to be bled. It is important to note that excessive air in the brake system will cause a soft or spongy feeling brake pedal. During the brake bleeding procedure, be sure the brake fluid level remains close to the FULL level in the master cylinder fluid reservoir. Check the fluid level periodically during the bleeding procedure and add DOT 3 brake fluid as required.
The ABS portion of the brake system must be bled separately. Use the following procedure to properly bleed the brake hydraulic system including the ABS.
BLEEDING
When bleeding the ABS , the following bleeding sequence must be followed to insure complete and adequate bleeding.
(1) Make sure all hydraulic fluid lines are installed and properly torqued.
(2) Connect the DRBIIIt scan tool to the diagnostics connector. The diagnostic connector is located under the lower steering column cover to the left of the steering column.
(3) Using the DRB, check to make sure the CAB does not have any fault codes stored. If it does, clear them using the DRB.
(4) Bleed the base brake system using the standard pressure or manual bleeding procedure. (Refer to 5 - BRAKES - BASE - STANDARD PROCEDURE)
(5) Using the DRB, select ANTILOCK BRAKES, followed by MISCELLANEOUS, then BLEED BRAKES. Follow the instructions displayed. When the scan tool displays TEST COMPLETED, disconnect the scan tool and proceed.
(6) Bleed the base brake system a second time. Check brake fluid level in the reservoir periodically to prevent emptying, causing air to enter the hydraulic system.
(7) Fill the master cylinder reservoir to the full level.
(8) Test drive the vehicle to be sure the brakes are operating correctly and that the brake pedal does not feel spongy.
During this process an unknown quantity of fluid escaped from the ABS unit, so it MAY need to be bled. (I think it was only a small amount, but am not really sure.) The procedure below says I need to bleed the ABS system; however it requires a DBSIII, I do not have one, none of my local part stores has one for loan, and I have heard that they cost $1,500.
So, my questions for you experts are:
1. referring to the procedure below, if I just bleed the standard base system, and there IS air in the ABS, what will happen when I start and drive the vehicle?
- will I get a check engine light or other diagnostic warning on the dashboard?
- will the pedal be spongy?
2. If the pedal is not spongy and the brakes seem to be operating normally can I assume everything is okay and the ABS system does not need to be bled?
This procedure is from the service manual for my 02 Grand Caravan:
STANDARD PROCEDURE - ANTILOCK BRAKE SYSTEM BLEEDING
The base brake’s hydraulic system must be bled anytime air enters the hydraulic system. The ABS though, particularly the ICU (HCU), should only be bled when the HCU is replaced or removed from the vehicle. The ABS must always be bled anytime it is suspected that the HCU has ingested air. Under most circumstances that require the bleeding of the brakes hydraulic system, only the base brake hydraulic system needs to be bled. It is important to note that excessive air in the brake system will cause a soft or spongy feeling brake pedal. During the brake bleeding procedure, be sure the brake fluid level remains close to the FULL level in the master cylinder fluid reservoir. Check the fluid level periodically during the bleeding procedure and add DOT 3 brake fluid as required.
The ABS portion of the brake system must be bled separately. Use the following procedure to properly bleed the brake hydraulic system including the ABS.
BLEEDING
When bleeding the ABS , the following bleeding sequence must be followed to insure complete and adequate bleeding.
(1) Make sure all hydraulic fluid lines are installed and properly torqued.
(2) Connect the DRBIIIt scan tool to the diagnostics connector. The diagnostic connector is located under the lower steering column cover to the left of the steering column.
(3) Using the DRB, check to make sure the CAB does not have any fault codes stored. If it does, clear them using the DRB.
(4) Bleed the base brake system using the standard pressure or manual bleeding procedure. (Refer to 5 - BRAKES - BASE - STANDARD PROCEDURE)
(5) Using the DRB, select ANTILOCK BRAKES, followed by MISCELLANEOUS, then BLEED BRAKES. Follow the instructions displayed. When the scan tool displays TEST COMPLETED, disconnect the scan tool and proceed.
(6) Bleed the base brake system a second time. Check brake fluid level in the reservoir periodically to prevent emptying, causing air to enter the hydraulic system.
(7) Fill the master cylinder reservoir to the full level.
(8) Test drive the vehicle to be sure the brakes are operating correctly and that the brake pedal does not feel spongy.
#2
10-28-2014, 08:20 PM
really you should have the entire system power bled and the fluid replaced, however, I have gotten by with just bleeding the line that was replaced, hold the pedal and crack the line at the abs unit, and the same on the other end until fluid had filled the line completely and no air is coming out of the bleeder screw. If your pedal feels good I would have to assume you bled the system at the corresponding wheel? you should be good.
#3
10-29-2014, 08:27 AM
I have bled the entire BASE system twice - once before removing the old parts (to get the old dirty fluid out of the system) and again after installing the new parts. A friend tells me if the ABS unit (ICS) needs to be bled it will throw a code. I have road tested the vehicle, I do not get a check engine light or an ABS light on the dash and the brakes are working perfectly. I tried a 'panic stop' to see if I could lock up wheels and couldn't. I don't know if that is because the ABS is working and prevented it or if it is because the pavement was dry and traction was good enough that wheels wouldn't have locked anyway but I suspect the former. So I think I am good.