2004 Cruiser COMPLETE loss of brakes!! ??

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S

sf76

10 Year
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Aug 21, 2011
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While driving back to Seattle from Montana this weekend I experienced a complete loss of brakes. I was towing my travel trailer and fortunately was able to stop by using the manual control on the brake controller (trailer brakes.) I unhooked the trailer and had zero brakes on the cruiser. The pedal felt a little soft but did not go to the floor. I had to use the parking brake to move the vehicle. No leaks in the system at all....fluid level perfect. When it happend a continous alarm sounded and 4 lights came on. ABS, BRAKE, TRC, TRC OFF. It happened right as a hit a fairly large bump in the road. I had it towed to a dealer in Idaho. The service writer said that he had "never heard of this before." I recieved a call from him the next day and he states that the brake booster pump failed and needs to be replaced. $2000 installed. This makes no sense to me as I thought that the booster was a vacuum system with the purpose of increasing the pressure between the pedal and the master cylinder. I don't understand how booster failure would cause complete, instant, loss of brakes. What am I missing here? Thanks in advance for any info!

Scott
 
The LC uses an electro-hydraulic system. An electric pump provides pressure to a hydraulic pressure accumulator which then provides a source of hydraulic pressure to the system. The pump runs intermittently as required by a pressure sensor. Think of it like a pressure tank in a pumped well at your house. There is no vacuum booster in the LC. You probably didn't have an instant loss of brakes, but rather the pump stopped building pressure in the accumulator which led to a loss of stopping force. You should, however, still be able to provide manual pressure via the pedal to activate the calipers... albeit with a large amount of force required.

The ATRAC, VSC, and ABS all run off the assembly which includes the pump, master cylinder, and ABS controller/valves.

A mechanic experienced with the system may be able to correctly identify the failed component and replace that for less cost. For liability and simplicity the dealer is quoting to replace the entire manifold (parts are about $1800 IIRC).
 
Thanks for the reply. By manifold you mean the accumulator, master cyliinder, and ABS controller/valves? The part that I find strange is that after I finally came to a stop and tried the brakes again there was NOTHING. I unhooked the trailer to confirm this, and again NOTHING...didn't matter how much pressure I put on the pedal. In drive, with park brake of,f at an idle with hard pressure on pedal, vehicle would roll as if no brake applied at all. The service writer did not mention replacement of the master cylinder or ABS controller...interesting.

Scott
 
Without the booster pump there is no pressure to rear brakes, but should have some braking on front brakes with lots of pedal force. I would be suspicious of another problem with front system. For testing in past I have disconnected booster pump power, emptied the accumulator and still had limited braking.
 
Same issue with my 99 last week

I ran into the same issue. Dealer will only replace the enitre assembly hence I bought the Master Cylinder rebuild kit for only $47 - it is a new piston with all new O-rings, etc. hoping this would fix my problem. After several attemps, it would still not function. My issue was that the pump motor would not kick on when it should with the key turned to "on" - I checked the pump by hooking it directly up to a 12v source and it is fine.

The issue for me is that the dealer would not put the time in to diagnose in the circuit what was keeping the pump motor from coming on - hence I had to pay the $1,800 for the part and $358 for labor to put it in. And this is what I negotiated after they told me it was going to be just over $3,000 for the same.
 
If recalling correctly, the (electric) booster pump runs for a short while after turning the ignition on (even w/o starting the engine). On mine, I can actually feel it "lifting" the brake pedal up, if trucks been sitting for a day or two.
Does you pump run at all during this "condition"?
 
ABS systems are mostly not vacuum assist anymore. They are pressure-based systems now. A high pressure canister provides the actual braking force and this is modulated by the ABS valving...that way the system can do all the brake force distribution and emergency maximum braking (i forget the marketing name) regardless of how hard the driver presses the pedal. As the brakes are applied the canister pressure drops. Once it gets too low there is effectively no brake assist and the ABS and traction control cannot function. You should still be able to stop the truck but it may take a full two legged stand on the pedal without assist.

The brake pump is a hydraulic unit that repressurizes the canister when it drops below whatever the setpoint is. You can hear it run (barely) when you first start in the morning and again every so many stops. If the pump goes out then the canister goes "flat", ABS/TRAC/EBD stop working, and all the lights come on.

It could also be a bad pressure switch that is failing to tell the pump to run.

FWIW i have a 2004 LX ( but no problems with the brake system so far).
 
Johnathn - you make a good point regarding that pressure sensor possibly being faulting. The problem I have is that the dealers are not making the effort to diagnose the problem withing the "Hydraulic Brake Boost System" and just pull it out as one unit and replace it with the new unit which lists for approx $2,400 (but they will come down to $1,800).

My pump motor would not come on my system sent the alarms and lights yet I could hear the relay click on when I put the ignition in the "on" position. I pulled the system, did the MC rebuild (new piston and O-rings) and bench tested the pump motor which worked. I then took it to the dealer and asked them to troubleshoot the sensors with their ODBII testers, etc. and they just came back with "it needs a whole new system.

Frustrating - wish I knew someone on the inside and they may have taken the time to do it.

Oh well, I am back on road and love my 100 - I was just hoping to use that cash on a SLEE ARB front bumper and winch!!!
 
Old thread but relevant questions.

I have a 2004 with 98k. It has developed a soft brake - but only the first push of the pedal. Release and push again and you get good brake performance. Sitting with engine running, of I pump the pedal 20-30 times quickly, I get ABS bells and whistles going off.

I plan to rebuild the MC. However, the loss of pressure after multiple quick pumps has me worried. Normal? What about first push being spongy but firm pedal with progressive pushes? MC issue or booster pump? I can hear the pump cycling with the hood up, BTW.
 
bamachem said:
I have a 2004 with 98k. It has developed a soft brake - but only the first push of the pedal. Release and push again and you get good brake performance. Sitting with engine running, of I pump the pedal 20-30 times quickly, I get ABS bells and whistles going off.

I plan to rebuild the MC. However, the loss of pressure after multiple quick pumps has me worried. Normal? What about first push being spongy but firm pedal with progressive pushes? MC issue or booster pump? I can hear the pump cycling with the hood up, BTW.
Click to expand...
Sounds like air.
The 20+ quick pumps > loss of pressure - is normal. Don't do that!
Spongy is air. If it isn't air - try bleeding again. Next would be MC recon. kit.
 
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I was going to start a thread over my EXTREMELY indecisive brakes over the weekend but figured I'd just ask here.

I wheeled VERY hard this past weekend. On the way home my brakes felt very mushy. I entered a corner at 60MPH (my everyday speed) and hit the brakes. The truck just would not slow down, I had to stand on them full force and barely got it to slow down, I almost cruised right into the ditch. I decided to drive around and do some more playing around to make sure it wasn't just that one time. Nope, seems like I lost 40% brake power. I'm not sure if this is brake fade from ATRAC working so hard earlier that day (I don't see how fade is possible 100+ miles later). My pads, rotors, and everything are still good. On to Sunday. I pulled out of the car wash and went to merge, I felt the wheel start pulling very hard and the little "out of control skidding vehicle" light came on and the dash was beeping for several seconds. I have had to apply more brake pressure today as well. I did jump my truck several times this weekend...could I of stressed something or blown a line/gasket? Maybe time for a MC rebuild? :/ It's been getting worse over the past few weeks honestly, I have always noticed it. But never to the point where I could not get the truck to slow down.
 
uHu said:
Sounds like air.
The 20+ quick pumps > loss of pressure - is normal. Don't do that!
Spongy is air. If it isn't air - try bleeding again. Next would be MC recon. kit.
Click to expand...

Definitely not air.

This has developed over the last 1000-miles. No brake maint in that timeframe to introduce air.

To be clear, when I depress the pedal once, it's soft and will go to the floor with very little braking force and very little pedal resistance until it bottoms out. If i quickly release and reapplication of the brakes results in a normal pedal firmness and normal braking performance.

If this was air, the braking performance would be consistently poor, correct?
 
Yes, the booster pump comes on for 10-seconds or so and cycles off. When I pump the pedal repeatedly at a stop to depleat system pressure and get the buzzers to trigger, I can hear the pump running as well. Pressure recovers in about 10-sec and the lights/buzzers go off.

Definitely not a booster pump issue. Liquid level is good and fluid is clean.

I'm thinking that the seals on the piston is allowing the assist pressure to leak down slowly, which is why the second pump of the foot feels "normal" but the initial pump doesn't.
 
The pistons certainly function normally. They grab when the master cylinder is sending the high pressure hydraulic fluid.

I haven't used ATRAC yet, and I've had it since December. Maybe I need to take it for a spin in the sand this weekend...
 
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