355 Teves brake system error

Hi everyone , you will have to bear with me a bit on this one as I’m in pretty deep trying to resolve this problem !! So we have a customers car which has intermittently had abs problems which have now become a permanent error , the vehicle is not priming the the pump at key on and the abs light is on , when I put the diagnosis fuse in the error is 2.1 which is for the main solenoid , I have tested the solenoid , it has been ultrasonic cleaned , this didn’t cure the problem , I have done comparative testing with a known good car , resistance check was 4.5 ohms on both vehicles , I have pulsed the valve while recording the amperage , both valves are 2.7 amps in operation , in desperation I have swapped out the whole brake unit including the ECU and the pump and accumulator assembly but still cannot revive the system ! I have had the breakout box on the system and run through the wiring , GND is good on terminal 1 , +12v is present at key on at terminal 2 , my first main error is terminal 3 is not being energised so the main relay is not switching on , as I understand it terminal 3 is energised from the main relay by an output from the ECU terminal 8 which is also not energising , I can only simulate this error on the known vehicle by un plugging the main solenoid creating an open circuit , I can’t fault the wiring unless I’m missing something ! It would really help to be able to understand the operating logic of the system as it may help working out a start point for diagnosis !! I have bridged terminal 8 to terminal 2 , this brings the system to life with the pump cutting in and out when the brake pedal is pumped so I’m pretty confident the problem is not related to the pressure sensor . If anyone has any ideas they would be gratefully received!!

 

So you've done a continuity check between the ECU (pin 18) and the main valve and also checked that (black/violet) wire for shorts to ground (with the plug disconnected from the ECU)?

Diagram here:

https://www.dropbox.com/t/sydavYVTjZ3i1jg0

(I'm not sure if you got your resistance value for the valve using a wiring check between pin 18 and ground)

 

https://www.dropbox.com/t/98C35rNe8WcIeTHZ

From the Teves Book:

Master cylinder and main valve diagnostic monitoring:

The main valve is continuously monitored by
the ABS CM. If the CM detects a main valve
or hydraulic pressure failure, the ABS system
is switched off, the ABS MIL is activated and
a DTC indicating the failure mode is stored.

From the above text, it's hard to tell if the valve itself is being monitored or the valve solenoid is being monitored. The following sounds like it suggests both.

2.1 code:
Main valve to CM circuit; open circuit, short circuit to ground or B+ voltage
Main valve ground circuit; open circuit, high resistance or short circuit to B+ voltage
Main valve failure
CM failure

But since you've replaced the module, I can't imagine that the valve itself is faulty.

 

Many thanks for the wiring diagram , much clearer than the original ferrari one i am currently using !! I currently have the wire to pin 18 isolated from the 35 pin plug and have the solenoid connected via the breakout box and i am using a chassis ground , so i have completely eliminated the vehicle harness. The error is still present . I feel like there is something else in the system that is creating this fault but not obviously linked ? I have read on another chat that a fault relating to the starter solenoid had created a random ABS fault but looking at your diagram this is not likely on a euro spec vehicle altough this is a fairly odd spec car being a motronic 2.7 spider with extended resonator tubes on the inlet which i have only seen on this car ! I will try and find out its original market destination .

 

It is a UK supplied car

 

Thanks for the confirmation.

The WSM Ferrari diagrams are based on Euro cars. The starter link is shown in my colour diagram (see splice 30014). To override the influence of anything in the starter system, remove the orange ABS relay and short out pins 87A and 30 on the relay socket. Note the non-standard configuration of the relay.

Looking at the base of the relay (not the socket), here is the pin configuration:

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So, looking at the socket...

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I doubt this will help though. You're getting key (accessory) power at pin 2. If the orange "cutout" relay was constantly energised by a faulty engine start system you wouldn't get key (accessory) power on pin 2. This also shows that the ABS Cutout Switch on the pedestal isn't activated/faulty (if you have this switch) and that the 3 amp fuse is ok. Do you get 12 volts on pin 2 with the car running and with the key just in accessory and ON (engine not running)?

Did both ECUs generate the same code or did both ECUs just exhibit the same behaviour? I'm just wondering if the original ECU is generating the wrong code, leading us in the wrong direction. I guess that is not likely as that would mean there were two faults in the system. ECU and ???

Sorry... running out of ideas here, too.

 

Miro, if you're out there? @m.stojanovic

If you need other clearer diagrams for other specific issues, don't be afraid to ask. I have diagrams like this for the 2.7 and the 5.2 for all systems (except the airbag system). Usually I don't give out full sets, however, as they are constantly being updated. When you said the main valve solenoid had a resistance of 4.5 ohms on both your cars, I added that to my diagram (thanks!).

 

Thank you again for your reply , the 12v supply at pin 2 is present at key on and also engine running , we have swapped out all three relays and the diode , I can try bridging out the relay out tomorrow when I’m back in work but as you have eluded to this probably won’t change the fault . We swapped the ECU from another known good vehicle and at first key on the 2.1 error was present . The WSM says the vehicle needs driving to clear the fault memory but as the pump isn’t priming unless I bridge pins 2 and 8 this isn’t really possible , I could put this ECU on another car to clear down but the one we tried has been returned to the client and I currently don’t have another Teves 355 available for testing . We may have to ask nicely and borrow the vehicle for some comparative testing
I will definitely take you up on your offer on wiring diagrams , I do have a fair few already , I’ll check what I have and can list out for anyone who needs them .

 

Sorry but I am quite busy packing at the moment as I am leaving Malaysia in about 20 days. If I see that I have a bit of time, I will look into this. Otherwise, I will be back to "normal" in a couple of months time when I settle down after moving.

 

Hi!

If you measured a resistance of 4.5 Ohms in the main valve terminals and pulsed it, the valve itself is ok. Did you tried to do a good cleaning in the valve electrical terminals and in the connector pins? I had a situation that I measured 4.8 Ohms with a multimeter directly in the valve terminals, but the ECU kept insisting in an error for the main valve. I realized that measuring the main valve resistance from the ECU connector pins that resistance was bigger, like 6 Ohms. So I did a good cleaning in the valve terminals and its connector pins with a sandpaper (in fact there was something like a varnish on the valve terminals) and I solved the mystery. After that the ECU did its check, pulsed the valve and turned off the ABS light, reading a normal resistance.

 

I have removed the valve and it has been ultrasonically cleaned while being pulsed, the resistance is 4.5 ohms at the 35 way plug on the ECU , i am measuring this via a break out box , i have also tried removing the wire from the 35 way plug and completely bypassing the loom straight to the valve , i have also swapped out the complete brake ABS unit with another car and the fault is still present , i have cleaned all the terminals so am at a bit of a loss as where to go next , I think i may try scoping the solenoid on this and a known good vehicle to see if there is any think strange happening at key on !!

 

Assuming the valve and solenoid are ok, could there be other reasons why the pump isn't running? I see the front wheel ABS is inhibited if the fluid level switches are showing low levels (There are separate level switches in the reservoir for control and for the dash warning light). This is stated in the generic Teves manual, but I don't know if there are variations on the Ferrari F355. However, even if the front and rear brake ABS is inhibited on the F355, I don't know if that necessarily equates to the pump not running.

The float switches in the reservoir which send a signal to the ABS ECU are identified as FLS2 and FLS2A in the wiring diagram. In theory, you could jumper pins 3 and 4 on the level sensor to simulate good switches. Alternatively, if you have the breakout box attached, you could short out pins 9 and 10 on the ECU.

Are the pressure switches mounted on the components you have swapped over? I see there is also a second pressure switch in series with the float switches FLS2 and FLS2A.

Sorry, clutching at straws here.

(EDIT: Disregard... after further reading, I see the F355 only turns off ABS on the front brakes, too, if the fluid level is low)

 

I did swap the entire unit including the fluid reservoir so level switches have been eliminated , my plan is to scope the sensors and solenoids as I key on and try and find what is different between this vehicle and a known good vehicle , I will be interesting to see what the ECU actually puts out as a test signal to each component, then hopefully I can figure out on a known good vehicle where the difference lies !

 

Thanks for the clarification. Not having any practical experience with the Teves system. I didn't realise the reservoir was mounted on the unit. The Bosch system is different.

 

So after a bit of a curve ball at the start I have got to the bottom of this ! I have hooked up the scope to see what signals are coming out of the ECU and have found that the it is not generating the test check signal to the main solenoid , fortunately we had another teves 355 in today and I jumped on it to get some reference measurements, on the known good car the ECU generates a 12v duty cycle which is continuous all the time and not just a key on test which makes sense for the safe function of the system , scope is definitely the best way to check as a multi meter will only show about 0.2v , I have attached a photo of the graph from the pic scope , we were curved balled on this problem as we had swapped out the ECU from another vehicle and it didn’t cure the problem although that particular car has had random ABS problems so we may of just been unlucky at the time of test !! Our next problem is where to source/ repair this ECU as they are no longer avaliable and eurospares want nearly £4000 for a second hand one !! If anyone has any company’s they have had a good experience with ECU repairs I would be grateful for your recommendations. Thank you for all the input from everyone, it’s been really helpful Image Unavailable, Please Login

 

Or.. worst case scenario... something is destroying the ECUs when you fit them (a wiring short on the original car). Or were both cars jumpstarted at any point?

Anyway, glad you seem to have found the problem. Sorry, can't help with a repair company.

 

You may give it a try with a Jaguar XJ40 or VW Golf MK2 ABS computer. Their part numbers are: Jag is DAC 5863 and Golf is 535907379. The internals of the Jag unit look most similar to those of the Ferrari's and the Jag diagram shows similar connections. We had a long discussion on the 355 Teves ABS here: https://www.ferrarichat.com/forum/threads/355-teves-abs-help.695018/ also here: https://www.ferrarichat.com/forum/threads/348-abs-computer-clarification.572644/

 

The Jag ABS computer I mentioned above is also used in Jaguar XJS.

 

Here are the Jaguar XJS ABS diagrams, 1989 and 1993:

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I think we may of struck gold and found a NOS ECU located in Germany for €2000 , we have ordered it , will update when it arrives , really appreciate all your help . Will save all this info for future reference

 

You may also wish to keep these Teves Mark II documents.

 

I also have a spare ABS computer laying around I would be willing to sell for cheap. Been having issues with my ABS and such on my Teves system and the dealer believed it was the ECU. Bought a used one, replaced it, same issue. Frustrating, but now I have an extra ABS ECU…

 

Hi guys , sorry for the long overdue update !! As I have now had two teves 355’s with intermittent frustrating faults I thought I would update you with my findings . On the original car the replacement ECU did cure the problem but we had a further intermittent fault prior to returning to the client , the vehicle would intermittently not prime up and using the fuse in the diagnosis holder did not bring up any flash codes , after some comparative testing I found that the large green pressure sensor was not supplying an earth to allow the pump to build pressure. The slight curve ball I have discovered is that according to the workshop manual when there are no faults with the system the fault memory is deleted when the vehicle is driven over 40kph , this is not always the case so you can be left looking for a previous fault that is no longer present!! This leads me into the second car that I have had an intermittent fault with , this vehicle would also flash previous codes even though they were absent , I proved this by disconnecting one of the wheel speed sensors and then reconnecting it , the fault did not clear from the ECU after a drive cycle ! This car was driving fine with the pump priming but occasionally flashing the ABS light , after much frustration I managed to trace the fault again to the large green pressure sensor but with different symptoms . There is a check circuit from pin 9 to pin 10 which runs through the level sensors in the master cylinder reservoir and also passes through the pressure sensor , it is a12v lin circuit which actually runs at about 7v when everything is connected and working correctly , the pressure sensor would occasionally go to ground internally which then brings the warning light on , there is no flash codes for this so no error is recorded! This pressure sensor is not available from Ferrari but I did manage to cross reference it with a Porsche and managed to order it on an exchange basis from the main dealer , they are not cheap !! So if you have any weird intermittent faults have a good look at this sensor !!!!

 

Interesting. I would have expected that the fault would remain in memory (to diagnose intermittent faults), so it suprised me to hear that the manual says this.

Both the level sensing system and the pressure sensing system have multiple contacts and, as you say, some of them go to the ECU for fault reporting.

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Thanks for the information.