348 ABS question

Hello Ernie. The ABS fault code I am getting is #25. Indicates a faulty right front return valve. I believe the ABS electronic unit detects the fault at start-up when it runs diagnostics. I am not getting a whell sensor fault code. Be a whole lot simpler of it was a wheel sensor or connection there. Thanks for the help, John.

 

Thanks No Doubt. My understanding is that my multi meter(diode test setting) is testing with a voltage of 1.5 volts. I am getting a forward voltage drop reading of 0.476 and 0.522. The sites I have researched regarding diode testing state a value of 0.5~0.8 volts indicates a good silicon diode. Again I could be completely off base. I am testing at the flat pins not the actual diode ends. The diodes are encased in a plastic box. I am using the schematic on the outside of the diode box to determine pins to test and current direction. The reading 0.476 is out of spec. 0.522 is close to the lower spec limit if my understanding of all this is correct. Perhaps best to order the diode box from Daniel at Ricambi and see if that solves the problem. Thanks again, John.

 

Noah, thank you. My hope is that when I send the ECU to BBA to be repaired they can determine the unit was in point of fact at fault. Would be a real kick in the butt if the ECU comes back from the re-manufacturer and the problem persists! Thanks to you, No Doubt and all the others who provided information and help this has been a real learning experience! Thanks again. John.

 

The saga continues! Just got off the phone with BBA Remanufacturing. They tested the unit as best they could but found no defect. In talking to the tech at BBA it appears there is no definitive test for these older ATE Teves ABS units, at least for BBA. I asked if they connect the unit to a piece of equipment to determine function and he replied “no nothing that extensive”. The newer units are apparently more test friendly! Bottom line is this part could still be the problem.
Obviously this does not help resolve my problem. I am now back to square 1. BBA can rebuild/ replace the solenoid valves if they are the failure point. As indicated in an earlier post, my testing indicates the valves are fine. I will test again to eliminate the valves as a possible variable. May have to bite the bullet and simply buy new relays to eliminate them as a failure point. The relays tested fine but perhaps 1 is weak. Daniel at Ricambi has sourced them for me but as Daniel pointed out expensive little suckers!
I sent the unit to the US BBA facility here in MA. Perhaps the UK facility has more experience with this particular ABS electronic unit. Has anyone used BBA to rebuild/ repair this part?
Picked up a complete “looks like new” pedal box assembly(ebay) cheap a couple of years ago. All the ABS solenoid valves are included. Should have bought the ABS ECU he had also! Hindsight is always 20/20!
I admit to being somewhat at a loss. Any and all suggestions welcome!

 

Hello No Doubt. Ordered the Diode Box from Ricambi a week or 2 ago. Daniel is trying his best to locate the part. Relays range from $50~$70 each. Did not order at that time because they appeared to test fine. I will order the balance today from Ricambi. Appears some 348 parts are getting difficult to locate!
Thank you again for your kind offer to test with your electronic unit if the fault remains after relay and diode replacement. I will take you up on the offer! My concern is if there is another problem source will this render your unit inoperable? My experience here is limited or none.

 

Latest update. Installed new diode box and relays. Bad news! The ABS light remained on. Test drove over 30~40kph as the manual states. The system did not reset. Ran the diagnostics and got the same 25 code. Appears, if my test procedure is not flawed, the ECU is the faulty part.
No Doubt if the offer is still open please advise. Thank you for all the help thus far. John.

 

Back to Square 1! Installed the loaner ECU No Doubt was kind enough to send Friday evening. Started car, ABS light did not go out. Drove car, ABS light remains on. Ran diagnostic, code 25 again. Fault indicated is Right Front Return Valve. The good news is this rules out a faulty ABS ECU. The bad news is I am back to the beginning. I plan to repeat my “Jumper” test of the solenoid valves. Additional attention to the Right Front Return and Delivery valves. I have a spare pedal box from a 355 challenge, may install to hopefully solve the problem. Not a pressing priority. My brakes work fine just no ABS function. Again, I would like to thank everyone for all the help and suggestions. John.

 

ABS Update
After 2 years of occasional attention I am now seriously evaluating the problem and planning to finally complete repairs.
I again ran the diagnostic tests as detailed in the Ferrari workshop manual. Net result is the tests indicate the diagnostic code is correct. My Right Front Return Valve is not functioning.
To further confirm and rule out a possible electrical problem between the connector and the ABS Modulator I powered the modulator direct.
I disconnected the 7-pin connector at the master cylinder where it feeds into the modulator.
Using the wiring diagram Daniel was kind enough to provide I determined the ground pin and the remaining 6 pins and associated valves.
The pin inside is ground. Jumped to the modulator body housing.
Pin next to the ground powers the valve in question. I pulled 12v from the fuse box and jumped to the pin. Nothing.
The remaining 5 pins when powered give a distinct click. Sounds like a switch or relay. They also spark slightly at contact.
Failed valve pin yields no audible sound or spark. Dead.

Now my questions:

Is my tests valid or a waste of time?

Is this a common failure? This is the same ABS system used in the late 328,348 and 355.

Can the Modulator be rebuilt/ serviced? If yes recommendations?

I purchased, several years ago, a complete pedal box on ebay. I tested the valves direct on that box and had several dead pins. So either the spare pedal box has a bad ABS modulator or my test is flawed.

All help appreciated.

 

Verell, Thanks. Will Do!