355 ABS Problem-Possible By-Pass Unit | FerrariChat
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355 ABS Problem-Possible By-Pass Unit

Discussion in 'Technical Q&A' started by ang308, Nov 16, 2007.

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  1. ang308

    ang308 Formula Junior
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    #1 ang308, Nov 16, 2007
    I have been having such a huge headache with my ABS system on my 95 355. I am not getting any rear brakes-pedal is as hard as rock. Everything pointing towards an accumulator problem. I have replaced master cylinder/abs unit, accumulator/pump assembly, and relays to no avail. The only thing that is left is the ECU. I am not getting fluid to go to the rear brakes.
    Do they possibly sell a master cylinder assembly that does away with the abs or something because I am going crazy. Code comes up 2.1-something about a left valve. Well everything has been changed. Dont know what to do.
     
  2. No Doubt

    No Doubt Seven Time F1 World Champ

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    #2 No Doubt, Nov 16, 2007
    Your ABS ecu can't make your brake pedal hard.

    On the other hand, a failed rear brake proportioning valve could make your brake pedal hard, as could a clogged or swollen brake line or other mechanical problem.
     
  3. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #3 fatbillybob, Nov 16, 2007
    can you go through your diagnostic steps and your solutions so far? Maybe we can figure this out. If not you can gut the system drop about 30lbs and go with a nonferrari master and pedal unit
     
  4. ang308

    ang308 Formula Junior
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    #4 ang308, Nov 17, 2007
    I have went online and found a good diagnostic check site at www.albeedigital.com/supercoupe/articles/abs-system.html. I ran through all those tests. One thing I am curious about though, on my pump assembly unit w/accumulator, the pump gets hot-(is this normal)? And it doesnt seem to suck in the fluid--so is the pump working or is it just getting hot?
     
  5. ang308

    ang308 Formula Junior
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    #5 ang308, Nov 17, 2007
    These are some of the procedures I have done according to the Ford Supercoupe website--they share the same exact ABS unit-even our wires in the Ferrari have Ford written on the connectors
    Basic Troubleshooting

    Most of the problems associated with this system seem to revolve around the electrical operation of the Hydraulic Pump Motor and the Accumulator. So lets describe what some of the common symptoms are and what you can do about it.

    Hard pedal Amber Anti Lock and Red Brake Light always on.

    The hard pedal is indication of no power assist which we now knows means the Accumulator is not pressurized or the hydraulic pump is not running to pressurize the system. You should also realize that you don’t have ANY rear brakes too. Run the Self Test and see the Amber Warning Light goes out in 4 seconds. Have an assistant stand by the open hood to listen for the Hydraulic Pump Motor to run when you start the car.
    If the pump runs, most likely you have a bad Accumulator or the pump is not being supplied with fluid because sediment has plugged the low pressure hose leading from the reservoir. Check the hose is unplugged and if that doesn’t correct the problem replace the Accumulator. If this doesn’t fix your problem you are into a high buck Pump Assembly replacement. (You already replaced the Accumulator so don’t buy another one now). For reference you should be able to press on the brake pedal from 5-8 times without the Hydraulic Pump Motor running. If this is not that case you are due for an Accumulator soon.
    If the pump does not run you now most likely have an external electrical problem although it is possible the pump motor is shot. Here is how to tell what is what. With the Ignition Switch off depress the brake pedal 20 times to ensure the system is fully depressurized. Turn the Ignition Switch to Run the pump should run. If not disconnect the 4 pin connector on the pump. Use a multi meter to measure the voltage on the pins of the harness connector. The two positive pins are on opposite side of the connector as are the negative pins. Measure from one positive to one negative pin. (See figure 3).You should measure more than `10V DC. If you don’t, potential problems include either the Hydraulic Pump Motor Relay, The Pressure Switch or the wiring harness between them all.

    Figure 3 Four Pin Motor Connector


    Figure 4 Hydraulic Pump Motor Relay Schematic and Pin-out

    The failure of the Hydraulic Pump Motor Relay is a common occurrence. The normal failure modes are the contacts welded themselves shut causing the Hydraulic Pump Motor to run continuous or the relay failing to close which prevents normal pump motor operation. To verify relay operation it would be possible to disconnect the harness connector to the Anti-Lock Pressure Switch and ground pin 4 of the connector to ground.(See Figure 5) This will complete the circuit for the coil of the Hydraulic Pump Motor Relay and should cause the pump to turn on. If the pump does not run most likely the relay is bad and must be replaced. If the motor does run the Pressure Switch may be the faulty part and should be replaced. The FORD Shop Manual states that if the Pressure Switch is replaced the Hydraulic Pump Motor Relay should be replaced as well.
     
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  6. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #6 fatbillybob, Nov 17, 2007
    What happens when you try to bleed the brake system at each wheel? When doing a 2 man bleed can you bleed the rear brakes? When you have everything off and you step on the brakes it is rock solid? Now can you open a bleed screw and get the pedal to go to the floor? If you were to slowly drive the car do the brakes work at all? Can you lock the brakes and basically flatspot the tires? Or do you feel the pulsation of the ABS action through the pedal?
     
  7. ang308

    ang308 Formula Junior
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    #7 ang308, Nov 17, 2007
    When I bleed the front brakes they bleed normal and pedal goes to the floor. With the rear brakes-nothing happens. The pedal is still hard and does not go to the floor and no fluid comes out. It is the wierdest thing
     
  8. No Doubt

    No Doubt Seven Time F1 World Champ

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    #8 No Doubt, Nov 17, 2007
    Is your ignition key turned to the Run (not Start) Position II when you are trying to bleed the rear brakes?
     
  9. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #9 fatbillybob, Nov 17, 2007
    I don't think that is an abs problem but a basic obstruction in the brake lines. So if you crack the bleeder on the LR or RR you get no fluid bleed just a rock hard pedal. But if you bleed the RF or LF you get a normal bleed. If yes the next thing I would do if trace the rear brake lines from the claiper to a common junction point. Then I would crack the fitting JUST upstream of this point and see if you get pedal travel and fluid expulsion upon brake pedal depression. I would keep doing this all the way back to the master to try and find the bottle neck. Have you done this?
     
  10. ang308

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    #10 ang308, Nov 17, 2007
    I have the key on the run position when I do everything. First of all the pump gets hot(really hot-which I dont know if this is normal). The pump I am talking about is located next to the fuse panel. And I checked as far upstream as possible to see if fluid is coming out and nothing comes out. By this I mean I have been checking right at the master cylinder. There are three lines (well actually four lines coming out of the master cylinder-one which is located near the clutch slave cylinder which actually is the return line from the pump-nothing comes out of there either. OK now there are three lines coming out of the master cylinder located at the bottom of the assembly unit. The two outer lines are 11mm lines and they go to the front brakes. When I do the two man bleeding procedure-fluid comes out of these two lines and pedal goes to floor. The middle line (13mm) goes to the rear brakes. When I open up this line nothing happens. No fluid comes out and no pedal goes to floor and remains hard. So if I am not getting fluid out of here it is not going to the rear calipers. Now it did this with both ABS/Master Cylinder units. Which means my first one was probably not defective to begin with. This has been driving me insane. I am thinking about gutting out one of the master cylinders, if it could be done, and having an ABS-less car. It seems that something is stopping the rear brakes part of the master cylinder to function.

    Thanks for all your help guys
     
  11. bcwawright

    bcwawright F1 Veteran

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    #11 bcwawright, Nov 17, 2007
    You said the pump assembly was replaced? If so is this a new pump assembly or one from a breaker yard? What about the accumulator? New or used?

    Sounds like a bad pump assembly to me.....does the motor run continuously?

    Did you check to see if the pump is getting fluid?
     
  12. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #12 fatbillybob, Nov 17, 2007
    1) Bruce has good questions...please answer them.

    2) Also, If you have key on from a depressurized system do you hear the pump running?

    3) As the pump runs up to pressure does it stop in say 15-20 seconds from say overnight over couple days? It should not be really hot just warm. It should not continuously run but pump up and stop. You should be able to open any bleeder and bleed off pressure and the pump should come on.


    4) If you pass #2 and #3 then ....If you have the key on and the system presurizes up then stops...if you now do a two man bleed on either front caliper and say go through 2-4 pumps of fluid does the pump come back on?
     
  13. No Doubt

    No Doubt Seven Time F1 World Champ

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    #13 No Doubt, Nov 17, 2007
    Last edited by a moderator: Sep 7, 2017
    Here's an ABS diagram. I'd want to make certain that hose #30 is wide open/clear.

    Can you show on these numbers where you bled and saw or didn't see fluid?
    Image Unavailable, Please Login
     
  14. No Doubt

    No Doubt Seven Time F1 World Champ

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    #14 No Doubt, Nov 17, 2007
    Last edited by a moderator: Sep 7, 2017
  15. ang308

    ang308 Formula Junior
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    #15 ang308, Nov 17, 2007
    I don't hear any noise coming from the pump it just gets hot. Hose #30 in the picture is fine and fluid flows through it. I assume the pump is working because it was getting hot. My other pump did that as well. When I disconnect the hose from the pump assembly it does not look like it is sucking any fluid. Can it possibly be that this pump is bad-what are the chances that both pumps are bad? Anyway to rebuild them or just order just a pump? It possibly can be the pump is not working. I would hate having to go buy a new one and that not being the problem. When I connect 12 v to the pump it gets hot I dont hear anything coming from it.
     
  16. ang308

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    #16 ang308, Nov 17, 2007
    Yes actually it was from a 355 that has been parted out to be turned into a racer and I assume it was working.
    The pump is getting fluid just not returning it. The original that was on the car was working fine before the car sat for about a year. Now this other one does the same thing. It can possibly be that both are bad but its just weird that both are not working. I know it happens.
    I am getting voltage to the pump.

    Thanks again guys but I am itching to get this car up and running again. Its been a while
     
  17. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #17 fatbillybob, Nov 17, 2007
    Hold the presses...This is at least one major problem right there. The pump noise is audible from 15ft away even with motor running! There is no mistaking this. Your pump may be hot but it is not working. The pumps may be warm but not hot to the touch.

    I still have a problem with the rear brakes however. I still do not understand why you get no fluid flow here. If the ABS dies it kinda defaults to regular pre-abs days and you get a warning light but the brake work. You can drive the car and lock up all 4 tires. Something else is going on. I am not sure if somehow fluid flow is being locked out by an internal solinoid valve. As a safety issue I can't see how this could happen. The default would always to be free flowing fluid so you could generate pressure. From a practical mechanical aspect I can't see how this could happen either. I need to study the diagrams
     
  18. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #18 fatbillybob, Nov 17, 2007
    It is faster to fix what you have than reengineer the system with say tilton tandem master system with balance bar then figure out the brake bias and have a safe place to test it like not on public roads.
     
  19. Darolls

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    #19 Darolls, Nov 17, 2007
    My mechanic just had the exact same problem with a customer's car. There was sediment in the line going to the pump, and in the pump itself. He cleaned the MC, lines and disassembled the pump and cleaned it too.. The pump ran but wouldn't pump.

    The customer found a used pump and bought a valve and accumulator. I believe the parts cost was about $3K.

    The problem is now solved, but if the used pump fails, the customer will be out another chunk of change!
     
  20. ang308

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    #20 ang308, Nov 18, 2007
    According to what I have read up about the ABS unit in the car(Teves Mark II ABS) if:
    "Hard pedal Amber Anti Lock and Red Brake Light always on.

    The hard pedal is indication of no power assist which we now knows means the Accumulator is not pressurized or the hydraulic pump is not running to pressurize the system. You should also realize that you don’t have ANY rear brakes too. Run the Self Test and see the Amber Warning Light goes out in 4 seconds. Have an assistant stand by the open hood to listen for the Hydraulic Pump Motor to run when you start the car."


    Also this paragraph explains how the rear brakes are affected:

    2. Electric Pump and Hydraulic Accumulator Assembly (Figure 2)
    # The ABS System uses stored high pressure brake fluid as a source for power assist as well as for the rear brake circuit. The Pump is controlled primarily by the attached pressure switch which senses Hydraulic Accumulator pressure. The Accumulator is a Gas filled reservoir which contains a flexible diaphragm. When the pump runs, it forces brake fluid into the accumulator where it presses up again the diaphragm. This pressurization continues until pressure reaches approximately 2650 PSI. At this point the pressure switch opens allowing the Hydraulic Pump Motor Relay to drop out causing the pump to stop. The pump motor is protected by an internal thermal switch. If the motor overheats due to prolonged running (20 minutes continuous or so) the thermal switch will open shutting off the motor for 2-10 minutes until it cools down. The electrical operation of the system will be detailed later. The Accumulator and Pressure Switch are serviced separately while the pump and motor is serviced as a unit.
     
  21. bcwawright

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    #21 bcwawright, Nov 18, 2007
    Going to stick my neck out here. I want to preface what I'm about to say with this: I do not work on street cars! My experience is strictly with race cars,some of which have ABS. On a RC this system is highly complex and different than what comes on a SC......it uses a highly complex computer which may or may not integrate thru electro/mechanical means the traction control,launch control, and in some cases even the active dampening/suspension. I am NOT an expert on the Teves system, so if others can contribute where I fall short it will be welcomed.

    For the prurpose of this discussion I will state in generic terms which may NOT be necessarily specific to the 95 F355.

    The brake fluid reservoir has 2 main gravity outlets....1 feeds the front part of the antiskid hydraulic control station(what you call the master cylinder), the other feeds the brake control pump, which in turn feeds the rear of the hydraulic control station. It appears the design of the control station is for safety,i.e. if the pump,accumulator,motor,fuses,relays,ECS,or wiring loom fail the front brakes will work....but, the rear brakes become inoperable. That is why in your situation brake fluid flows to the front brake system but there is no flow of fluid to the rear brake system. The hydraulic control station has to be pressurized thru the inlet opening(hose #21) for rear brake operation.

    You can check to see if the pump/motor/accumulator is in fact pressurizing the hydraulic control station by removing hose #21. Use "EXTREME CAUTION" when doing this as there is high presuure fluid coming from this hose...depressurize the system before disconnecting.

    It appears that you have replaced good parts(waste of money), and have not addressed the part causing the problem.

    I agree with FBB. Simply because a motor is hot DOES NOT mean it is working....the pump can be seized or the motor. Either way I would have thought that the internal thermal switch would have cut power to the motor.

    FWIW, there are alot of parts that can be safely used on this car that are in "USED" condition....I would be vary cautious in using these kind of parts in this area of the brake system. Also, there are many parts of the car that a unskilled DIYer or moderately skilled person can work on......this part of the brake system has to be done right or you could find yourself in a very dangerous position....and no one wants your life or the lives of others to be at risk due to a few $$$ savings.

    Best of luck...
     
  22. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #22 fatbillybob, Nov 18, 2007
    Well it appears that the rears are controled on the pump/abs unit. I think it is funny that if the unit dies you get front brakes only. I would think the defualt would be for safety meaning you have front and rear brakes just no ABS function and two warning lights. But perhaps they want a dramatic feel of brake loss by only having the fronts as default. I would think this would encourage spinning the car. Anyway...that theory aside you need to resolve your pump/motor issues. The pump may be frozen and working but the motor inside is not turning. I do not know if you can take the internals apart to see what is happening. The pump may be like a swiming pool pump where you have an electric motor that drives an impeller unit and your impeller nit is frozen preventing the motor from turning = get really hot . If you fix this and get rear brakes the theory is valid.
     
  23. Testa

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    #23 Testa, Nov 18, 2007
    With a impeller type pump you will not get the high pressue which is necessary for the brake. We are talking about aprox. 180 bar here .... If the pump is not turning (as already stated in this thread you will hear it turning) but getting hot then you will have to replace the complete hydraulik pump. Since some cars during this time had a Teves MK II ABS system you should look for the partnumber (not the Ferrari partnumber !) and ask you local ATE dealer.
     
  24. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #24 fatbillybob, Nov 18, 2007
    I completely agree. However, the part was made so it can be opened I would guess. See if you can break it loose to get it to limp along to see if the rear brakes will allow a bled. Then you know you are on the right track. Why not get a pump from the T-bird where you got all the ABS dx data? Testa is correct go by the part #
     
  25. ang308

    ang308 Formula Junior
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    #25 ang308, Nov 18, 2007
    OK guys last night I took apart the whole assembly and guess what you were right. Pump turned but impellor(?) was frozen. I disconnected the pump and ran 12 volts straight from the battery. Pump spins. The nozzle of the pump goes into a metal impellor which was frozen. I loosened it up and eventually spun freely. I put it back together and everything spins. I hooked it up back onto the car and pump is spinning which you can hear. But again no fluid coming out of assembly. Pump will not turn off and no fluid is coming out of pump. Fluid is going into pump just fine. I change the accumulator-which maybe is causing not to get pressure. Still nothing. So it definitely has to do with this assembly. So why now that the pump is spinning am I not getting any fluid coming out whatsoever?
     
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