My wifes 2001 4Runner warning lights lit up last night. "ABS", "VSC", "TRAC" and "BRAKE" warning lights and audible chime all of a sudden went off when she started the vehicle last night, a few hours before everything was fine. The brake pedal definetly has no "power boost", is VERY hard to depress with VERY little stopping power available, basicly no brakes.

There are no obvious vacume leaks, all brake fluid levels are correct and there is no "CHECK ENGINE" light or DTC's in the OBD. I'm pressuming a sensor or ecu failure, but without a DTC how do you diagnose??

I'm not familiar with the 4 runner system. Are the master cylinder booster and ABS system are one combined unit? I don't remember Toyota ever using these type systems. The hard pedal makes me thing no power assist. Most system Toyota uses have vacuum operated power brake boosters.
Do some basic checks: Make sure the brake fluid is full
Make sure no vacuum hose are off, bad or obstructed.
Make sure all your brake lights are working, even the center light.
Hopefully we can get some more information here to help you.
Mike

I haven't been able to find any information on what ABS system Toyota uses on your 4runner. But maybe this can help. The ABS, VSC, and Trac are all related systems but the brake light usually comes on independently when there is a problem with the base brake system. Now any problem with the base brakes system will also shut sown the other systems hence the other lights.
I have not found any indication of Toyota using an thing but a vacuum boost brake systems and if this is the case and you have a hard pedal with no assist, I would be looking at the power brake booster. Some manufactures do have a low vacuum sensor. I don't know if this is the case here. OBD II codes will not revealed ABS codes so you must check the codes on the ABS with a more advanced scanner.
Again I would take a close look at the booster and vacuum lines to it. Check the system for ABS codes and go from there.
Hope this helps,
Mike

Thanks for looking into this Mike.

ABS controller, master cyclinder and booster are all combined on this model. I did have the dealer diagnose the problem over the weekend, and turns out that the main abs controller is bad F@#$!!!! $2000.00 for the part and $1100.00 to install. I'm NOT pleased with this!!!! I've contacted a couple of local repair shops and they don't want the job, they have said this part requires a sophisticated (and I pressume dealer only??) ultra-high vacuume bleading process and computer re-calibration.

My whole life I've always worked on my own vehicles and race cars. Complete motor builds, transmission re-placements, rear end builds etc.... Having to have this done by someone else is exteremly frustrating and I'm having a difficult time comming to terms with it, but my 5 year old son and wife are the ones who are mostly in this car, so making a mistake on the install is also a concern. Is this truely a dealer only option??

Can you post a photo of the unit here on the forum?
Mike

Not any time soon. It has an approx. 3 inch diameter x 6 inch long nitrogen charged cannister on the right side of it, and on the left lower portion there is a plastic cover (3 or 4 inches x 6 or 8 inches) that has dozens of 3/8 inch diameter balls in it (I pressume these are all the solenoid valves). Several hydralic lines going between valve bodies etc..., definetly not a "conventional" master cylinder/power boost assembly.

The nitrogen canister tells me a lot. I am very surprised, I never new Toyota used these interrogated ABS units. And yes these can be a nightmare. I did cut my teeth in ABS work on these units commonly used by GM and Chrysler back in the early '90's.
I imagine most tech now days don't know how to work on these and that why they simply want to replace the hole thing. Then there may be a replacement parts issue.
Just from your description and some testing would be needed to confirm, but my guess it that the nitrogen canister your describe, the accumulator is bad. This is the most common failure on these units.
Mike

I thought about this some more and thought I might give you a run down on how this unit works.
This unit integrates the master cylinder power assist, ABS and traction control (or stability control) into one unit. Dump idea but engineers thought that since they needed a pump to pressurize the brakes for the traction control functions why not use it for power assist also. Then make it one unit, that's engineers for you.
There is an electric pump somewhere , may be attached and may be separate. This pump uses brake fluid to run a small hydraulic assist unit to give you power brakes. The accumulator ( the nitrogen canister) is separated internally by a rubber bladder. One side has the nitrogen gas and the other is pumped full of fluid under pressure and stored.
When you apply the brakes the power assist first uses the fluid in the accumulator and then as this pressure drops the pump kicks in and supplies the rest. It may continue to run afterwards as the accumulator is repressurized. But should shut off very quickly.
You problem is likely in some function of this.
The controller I would take to be the ABS ECU and this in my experience would be the lest likely part to fail. Besides, on these type units the computer is usually a separate unit or at lest can be separated for replacement.
I would go back to the dealer and ask for a code and the code description. Here's why. This could be a bad pump, a bad really or a bad accumulator. All that should be replaceable parts, if available. I'm just a little skeptical of their diagnoses.
Mike

Thanks again Mike.

Great description of the system, yes there is an electric pump just below the reservoir, and yes VERY DUMB idea when I look at having to have the system replaced.

I did not get specific codes, but I was told the entire system, controller, master cyclinder, booster/accumulator are one unit. Indvidual components are not replaceable with the exception of some relays etc... (which have been checked).

Very frustrating for me to have a vehicle that has critical/expensive system that I can not work on!!!!!!!

I did get the codes, C1223, C1251, C1252, C1256 and C1340.

The dealers official diagnosis is "brake booster motor does not turn on when power is applied direct to terminals".

This sucks!

This sond like a bad pump motor. It is possible but it's hard for me to believe they can't get a replacment pump. You could try some salvage yards.
Mike

Dose this look like the unit you have? This is a Teves itergraded ABS, quite popular in the '90s
Mike

It has those components on it, but it is definetly a different unit than the one pictured. Cylindrical not spherical accumulator on the opposite side of the assembly, boost motor mounted 180 deg. and lower on the Toyota assembly, different reservoir, etc..

I'm sorry most of my ABS books only go to '95 so I'm a bit out dated on specific information. Most of these units where made by a specific company and not the manufacturer. The Teves unit was very popular. Delco, Kelsey-Hayes, Bosh, and Nippon all made similar units. What makes your case even stranger is most had diapered by 2000. They were just too expensive to service as you have found out. I'm still supprised Toyota used this.
What are your plans? Are you going let Toyota fix it?
I know a shop owner out in CA and I'll check with him on his loaction.
Mike

This unit is a Nippon. You can bet the next car I buy will NOT have this type of system on it!!!

I'm not going to have the dealer fix it, and have found someone locally, with good references, who has had experience with these systems, and is 1/3 the price of the dealer estimate. But if your contact is in the San Jose area I'd very much like to talk to them also.

Still pissed I can't do it myself though!!!!

Thanks again for all your help,
Greg

I haven't heard back from my buddy yet, but I have found some more picture and a place that can likely repair your unit. remanufactured abs controllers pumps and modulators from bba-reman bosch teves lucas and all other types (http://www.bba-reman.com/content.aspx?content=remanufactured_abs_controller s_pumps_and_modulators_from_bba_reman_bosch_teves_ lucas_and_all_other_types)
I have never used them myself but we used to use Cardone for this. We would send ABS units like your in for rebuilding when we couldn't get a repair part.
Mike

If you do decide to do this yourself............
Here is some more information, brake bleeding procedure 4Runner
1. Perform this step only if the brake booster with accumulator pump is removed and or installed.
A. Turn the ignition switch off, depress the brake pedal 20 times or more, and release the pressure from the accumulator.
B. Fully depress the brake pedal 10 times.
C. Turn the ignition switch to the on position and start the booster pump.
D. Make sure the pump operates for 8 - 10 seconds. If the pump does not operate as specified, repeat and recheck the operation time.
2. Front Brake Lines:
A. Turn the ignition switch to the on position and wait until the pump motor has stopped.
B. Connect the vinyl tube to the brake caliper bleeder.
C. Depress the brake pedal several times, then loosen the bleeder screw with the pedal held down.
D. At the point when the fluid stops coming out, tighten the bleeder screw, then release the brake pedal.
E. Repeat until all the air in the fluid has been bled out.
F. Repeat the above procedures to bleed the other brake line.
3. Rear brake lines;
A. Turn the ignition switch to the on position and depress the brake pedal.
B. Connect the vinyl tube to the brake caliper bleeder.
C. Loosen the bleeder screw and release air.
D. When the air is completely bled out of the brake fluid through the bleeder screw, tighten the bleeder screw.
E. Repeat the above procedures to bleed the other brake line.
4. Perform this step only if the master cylinder solenoid is removed and or installed.
A. Connect the hand -held tester to the DLC3.
B. Turn the ignition switch to the on position.
C. Select "Active Test" mode on the hand-held tester.
D. Connect vinyl tube to the rear brake caliper bleeder.
E. Loosen the bleeder screw.
F. Select "SRMF & SRMR" to drive solenoids and bleed air from system.
G. Freest step F until all air is the brake fluid is bleed out.
H. When the air is completely bled out of the brake fluid through the bleeder screw, tighten the bleeder screw.
I. Repeat the above procedures to bleed the other brake lines.
J. Turn the ignition switch off.
K. Turn the ignition switch to the on position.
M. Clear DTC.
5. Check fluid level in reservoir.

Note number 4. This is why they say you need special equipment to do this. But I can tell you, you don't.
The Teves and Kelsey-Hayes systems bleed the same way. Also many other ABS system can trap air in the solenoid valves. We did repairs on these systems before they had two way scanning capability.
Here's the trick, get the brakes bleed as stated above and you'll likely find you have a good pedal. The problems happen after entering an ABS stop. Air will be released from the solenoid into the system and the pedal will go soft.
Set up in a vacant lot or abandon parking lot with lots of room. Be prepare to bleed the brakes several times.
If you drive there be aware that a stop engaging the ABS could leave you with very little pedal.
In the lot (not on the street) put the vehicle into several ABS stops, Gravel is great for this as you can get good activation at very low speeds. Once the pedal goes soft bleed the system again. Repeat until you notice no difference after an ABS activation, Make sure you have gotten a lock up on all four wheel so all solenoids have been activated.
Be save an careful when you do this and you can bleed out these brakes.
Mike

Mike,

Thanks for the instructions and the schematics, and the unit pictured is the one.

This will really get you, it got me! So last night I'm taking the car to the shop to get the work performed. Less than 5 minutes from leaving the house all of a sudden I have power assist with the brakes, a few seconds later all the warning lights and chimes turn off, everything is working fine. Now I'll drive it around until the failure happens again and perform some basic diagnostics myself to verify the conditions. I will want to at least verify signal/no signal to the motor and power (12 vdc?) directly to the motor.

Now at least I have some basic understanding of how this system works and will feel more comfortable at least giving it basic diagnostic and repair.

Thanks again for all the information so far Mike!!

Greg

You know that's not all that strange. I had a Teves unit in a Caddy do a similar thing. The guy had taken it to the dealer and had the pump motor replaced. While on vacation the light came on again and he lost his power braking, in the same way.
He stopped into our shop because we had a sign up saying we worked on ABS.
Here it was the relay. It would act up periodically.
The relays are cheap try the pump motor relay, you got very little to loose.
Mike

I will get another relay to replace the current one when the fault happens again, and I've heard it open and close on the right side of the car. Will there only be one relay and/or is there an electrical schematic available for the system?

I was also thinking about the bleeding process. If I put the rear-end on jack stands, then put the car in gear with the front wheels not moving, will this actuate the rear solenoids? That would make 1/2 the bleeding process a lot easier.


Greg

As I've said I am not familiar enough with the 4 Runners to tell you where the relaly is. Some of the domestics units I've worked on have the relay attached to the unit. But I would bet you have a large relay/fuse box under the hood and I bet the relay is in there and marked something like ABS Pump Motor.

If your vehicle is a 4 wheel drive I would not do that. Too risky, besides you would activate the front solenoids as these would not be moving (seen as a lock up) Then again the programing may be smart enough to know this is not right and simply set a sensor code.
Mike

It is 4 wheel drive, but the transfer case would be 2wd. I was actually thinking the traction control side of the system would engage and fire the solenoids. No brakes, in gear, would it see this as rear wheel slip?? But the abs seeing a font wheel lock up would fire the fronts when the brakes are applied, what I would want to happen also.

The BBA site was extremely helpfull also. They do not have the unit that is in the Toyota listed, but said there would be no charge to fix it if they could. If it turns out to be just the boost motor this would seem like an "easy" repair for them. Would the boost motor have some kind of seal that seperates it from the hydraulic fluid, enabling it to be removed from the system?

Yes, most likely the pump motor is replaceable. Problem with most of these systems, as you have found out the vehicle manufactures carry very little service parts. These rebuilders can somehow get the parts.
I just read a Motor magazine article about troubleshooting a Teves system on a 90 Olds. The accumulator was bad, and they said it was discontinued at the dealer. This was at one time an easy parts to get. They replaced it with a salvage yard part.
Mike

Been drving the car around for 2 days and everything worked fine. A couple of hours ago the failure came back. 12 volts at the motor when the relay turns on and the motor does nothing. The relay only stays on for 2-3 seconds only and then turns off, and back on again a few seconds later, and repeats over and over. Is this a normal condition to prevent electrical damage?

Looks like it's time to pull it out!

It is very possible that this is a normal, or there could be a breaker on this circuit and if the motor is pulling a lot of amps, the breaker will kick on and off.
Here is something you might try. If you can unplug the pump, try powering it directly off the battery. If it runs this way, then the relay is likely the problem. It could be causing a voltage drop, enough that the motor wont start up. This was the problem I had with the Caddy.
Then again if you get nothing, the pump motor is definitely bad.
Mike

Finally got the failure to last more than 10 minutes yesterday. Pulled the master cylinder assembly and then the pump motor, it does come apart and will go back together without any special assembly tools (I was a little concerned about that). The motor had an area on the armetuer/rotor area where the brushes make contact that was comming apart and causing the motor to "hang up" and not rotate. All the diagnoses and symptoms make sense that this would be the cause of my troubles. I will be picking up an assembly from a salvage yard today and switch the pump out.

When I removed the master cylinder I was very carefull to immediatly plug m/c ports and cap the brake lines with proper plugs and caps, maybe 1 or 2 drops of brake fluid out of 1 of the lines came out, that's all. I obviously will have air in the system when I re-assemble tonight and will go through the normal bleeding process, but I'm hoping that there will minimal if any air in the solenoid part of the system??

How many "lock up" sequences at each wheel should I acheive before I know that the system is completly bled?

Thanks again for all your help!!
Greg

If you keep the fluid from draining out it will be a pretty safe bet there will be no air in the solenoid valves. After it's together and bleed just do a few good ABS stops and see if the pedal gets softer. If it does then simply rebleed. But your doing the right thing by keeping the fluid in there, and I don't think you'll have any problems.
Mike

Mission accomplished. "Normal" bleeding went fine, several ABS stops and no difference in pedal feel.

My manhood has been restored! I was feeling defeated and demoralized a couple of weeks ago when I was confounded by this problem and thought I would have to have the dealer fix it, not mention a BIG $ savings.

Mike, your help here was the key enabling me to get this fixed, thank you again!

Greg

New technology is not as scary once you know the ins and outs.
Glad you got it fixed. :thumb:
Mike