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drummer69
Dodge Dakota
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2/27/2011
09:56:43
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 Subject: BRAKE FADE HELP!!!
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I have a 2001 dakota sport 4x4. ABS rear only. I have a problem I can not solve and I consisder myself a very good wrench. Upon appling the brakes the truck will stop then the peddle fades to the floor. This is what I have done. Replaced the master cylinder TWICE thinking I got a bad one from advanced auto the first time, bench bled it first. Replaced the power booster, replaced the combination/proportioning valve, bled this truck about 8 times. front to rear, rear to front, pressure bled it the same way. There is no air in this system that I can find. It is doing the same exact fading it did before I started all these repairs. NO leaks. I am blown away, and exhausted. When I bench bled the master cylinder I pushed the rod in all the way in to get the air out thinking that when depressing the brake pedal it also pusses it all the way in, was I wrong? Other than that I have done everything that I can think of, even the dealership was stumped saying they would have to do the job. But don't have the money to spend in the shop. Any ideas, anyone PLEASE HELP, lost....calipers and pads done 2 years ago still if they were the problem, wouldn't they be leaking. Also removed the rear anti lock system bock out of loop. It only works at high speeds and I never felt it kick in anyways. This has no effect on what I did because it was fading before the removal. Now I have just regular closed loop system.
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Bob Lincoln
Dodge Dakota
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2/28/2011
10:52:47
|  RE: BRAKE FADE HELP!!!
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I would not have removed the rear ABS. It probably gives you a warning light now.
Did you bleed the system properly? Here's the proper method:
Bench-bleed the master cylinder and install.
Open all 4 bleeder screws, and open the bleeder screw on the rear ABS unit. Leave them open until fluid starts dripping from all 5 screws. Then close all 5.
Bleed the rear ABS FIRST. Bleeding is done by stepping firmly on the brake and holding it down, while an assistant has a rubber hose from the bleeder screw to a bucket of brake fluid, with that end of the hose immersed the entire time. Open the screw while the brake pedal is being pressed, let fluid squirt out of the hose into the fluid bucket, and then close screw before releasing brake pedal. Repeat until only fluid and no more air comes out.
You MUST do the rear ABS first. Then do the right rear, left rear, right front and left front in that order.
If you didn't do it that way, that's why you still have air in the system.
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Bob Lincoln
Dodge Dakota
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2/28/2011
10:55:22
| RE: BRAKE FADE HELP!!!
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To bleed the master cylinder:
Install the master cylinder on the truck, disconnect the brake lines into it. Attach new short lines that curve up and point into the open master cylinder chambers. Top off the fluid. Step on the brake and let fluid and air squirt out of the temporary lines back into the master cylinder. Top off and repeat until only fluid comes out. Then disconnect the temporary lines and quickly hook up the regular brake lines to the master cylinder. Then bleed the rest of the system as above.
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drummer69
Dodge Dakota
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2/28/2011
11:18:18
| RE: BRAKE FADE HELP!!!
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Thanks guys for the tips on bleeding, but I did all That. There is no separate bleeder valve on the rear abs. Removing the rear abs solenoid block has no effect on the system other than not having it. It only works at high speed wheel slippage and then it only pulsates to even out the braking. It never kicked in as far as I know. Taking it out of the loop only gives me standard breaking. left the sensor plugged it as not to throw code. The is no air in the system. Thats why I'm stumped. The rear abs works on a ring gear sensor in the rear end that detects excessive speed differences in wheel speed that will cause it to activate.
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daddio
Dodge Dakota
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2/28/2011
13:13:56
| RE: BRAKE FADE HELP!!!
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I hate to tell you this but, the REAR ABS on my '00 works at any speed not just a higher rate of speed. It will kick in under 10mph.
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yea
Dodge Dakota
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2/28/2011
14:10:59
| RE: BRAKE FADE HELP!!!
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Quite a lengthy post so if I ever looked it
understand why.
Your problems could be caused by the caliper hoses.
(swelling up when brake is applied)
Have you changed them?
Have they ever been changed ?
(still factory original)???
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drummer69
Dodge Dakota
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2/28/2011
16:41:47
| RE: BRAKE FADE HELP!!!
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I understand about the abs but it has no bearing on the problem. It was doing this before the unit was removed so all I did was eliminate it as a problem Calipers and all hoses changed 2 years ago. I was under truck while my wife pumped brakes to check hoses, there fine and no bad lines or leaks. Is it possible I got 2 bad master cylinders 1000000 to 1.Note I'm a good wrench. Raced motocross for 10 years, always do my own work.
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Bob Lincoln
Dodge Dakota
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3/01/2011
08:51:47
| RE: BRAKE FADE HELP!!!
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The rear ABS unit on my 1992 Dakota DOES have a bleeder screw. I suggest you look at it again, if you haven't thrown it out. And it should trip an ABS light if you unplugged it.
I'd bleed it again. You'd be surprised how easy it is to aspirate air back through the bleeder screw. The longer it takes to bleed, the more the bleeder hose stretches and gets loose on the bleeder screw, and doesn't fit as tightly, and you can suck air back in there.
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drummer69
Dodge Dakota
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3/01/2011
12:08:47
| RE: BRAKE FADE HELP!!!
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pressure bled, is no one listening, no bleeder on abs!!!
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daddio
Dodge Dakota
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3/01/2011
12:44:11
| RE: BRAKE FADE HELP!!!
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Don't know if this will help or not but it is from the '01 FSM.
STANDARD PROCEDURES - BLEEDING ABS
BRAKE SYSTEM
ABS system bleeding requires conventional bleeding
methods plus use of the DRB scan tool. The procedure
involves performing a base brake bleeding,
followed by use of the scan tool to cycle and bleed the
HCU pump and solenoids. A second base brake bleeding
procedure is then required to remove any air
remaining in the system.
(1) Perform base brake bleeding. (Refer to 5 -
BRAKES - STANDARD PROCEDURE).
(2) Connect scan tool to the Data Link Connector.
(3) Select ANTILOCK BRAKES, followed by MISCELLANEOUS,
then BLEED BRAKES. Follow the
instructions displayed. When scan tool displays TEST
COMPLETE, disconnect scan tool and proceed.
(4) Perform base brake bleeding a second time.
(Refer to 5 - BRAKES - STANDARD PROCEDURE).
(5) Top off master cylinder fluid level and verify
proper brake operation before moving vehicle.
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Bob Lincoln
Dodge Dakota
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3/02/2011
08:37:59
| RE: BRAKE FADE HELP!!!
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Daddio, I think that's for the 4-wheel ABS. Rear wheel ABS doesn't have the same control mechanism. It only has the rear line feeding into it, and reduces pressure to the rear wheels if the sensor in the differential detects lockup. No scan tool or control is needed to bleed rear ABS.
drummer69, I just *suggested* that you would have a bleeder screw for the rear ABS for your year truck. I know for a fact that the 1992 does.
I still think you should bleed all 4 wheels again. When I replaced all my brake lines, I was getting a low pedal and no air coming out, but bleeding again suddenly produced the air that was trapped, and it's rock-solid now.
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ebtrr
Dodge Dakota
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4/25/2011
12:41:27
| RE: BRAKE FADE HELP!!!
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I am having exactly the same issue with a '98 SLT - rear ABS 4x4 5.2L. It had rusted out lines and I was not driving it and My neighbor replaced the lines in exchange for borrowing it. I know he bled it and the brake were working but a bit soft. Now they are not only soft but I get the same symptoms - initial stopping OK, then the pedal slowly goes down to the floor and the bakes start releasing.
I am wondering if you found a solution.
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