Hi I have issue and i would like to get confirmation about it. My abs light was jump wired from check engine light (pretty convienent) and when i discovered it, it was pretty obvious that there was issue that someone had "solved", and there certainly is. ABS light is constantly ON. Manual informs that theres powering issues of abs ecu. I have tested those relays, diode box and wires. Everything seems to work, except that ecu main relay coil doesnt get power to make it to connect (ecu pin 8). When ignition key is turned, ecu pin 2 sees suply voltage. So far, it seems that my ecu is toast, but i dont really understand those diodes yet. I did tested them and opened the cover and everything seems fine. Somehow ecu dont deliver power to mainrelay coil. Any thoughts?
So you're saying that 0.75amp white/red wire is powering the processors and relays inside the ECU? You're not the only one If the ECU is putting out a voltage (from pin 27) to illuminate the ABS fault light, why would it send a relatively small voltage on other wires that are rated at 2.5amps? Does someone have a circuit diagram for the ABS ECU internals?
For interested parties... Here is the diagram we are looking at... http://www.members.iinet.net.au/[email protected]/Ferrari348/Ferrari348ABS.gif
Abs ecu schematics would be nice to see. Ecu pin 27 should be negative, but its also connected to diode pin 87b (which is anode) Daaamn! More i look that schematic more confused it gets
I had a similar issue with my 348 abs system. I checked everything and eventually replaced the abs ecu box solving the light problem. Check late 80's Ford for compatible ecu JGW
Ah, my mistake. I didn't realise pin 27 was negative. I couldn't find any diagrams for the lamp itself.
Yes, ecu fault it seems. I need to check what alternative ecus there is, ferrari part is ridiculously priced. But, i still dont completely understand behaviour of that system and how that main relay should be powered, i think that when ignition is connected ecu performs some system check and when that comes out clear it released voltage to pin8 and when then comes power to pin 3 and 20 Warning light schematic is nowhere to find, but it should be easily discovered by looking at cluster
When you said the manual indicates that there are powering issues, did use some kind of diagnostic tool to interrogate the ECU to discover this? i.e. did the diagnostic tool give you some codes? Perhaps the ECU is not supplying power through pin 8 because the ECU is missing data from one of the sensors and doesn't want to turn on the system? Can the ECU detect a sensor fault with the wheel not moving? Do some codes latch the warning light? I've heard there's a procedure for clearing ABS ECU codes.
Could be, i have tested pretty much everything apart warning light circuit (as its nowhere to find) and main relay doesnt want to connect I have done tests with just multimeter, through ecu connector. Checked grounds and stuff. Diagnostic doesnt respond becouse light is constantly on (when ignition). What i dont know is how that light should behave, i suppose when you move your key to ignition, light should be on some time and then shut off? I have read that theres no way to clear error codes if youre not moving above 40kmh, and that is what i cant do atmo becouse its couple feets snow outside
Have you read the section on ABS in the 348 Workshop Manual? It has detailled instructions on ABS diagnostics. You have to insert a fuse into the empty fuse holder next to the ABS relays and then switch the ignition on. If you don't have the Workshop Manual, PM me and I will email it to you.
Yes, i have. Diagnostic doesnt respond, i guess becouse light is constantly on? Would ecu behave like that uf it sees error at self test from any input sensors? For what i see, warning light circuit receives ground always when main relay doesnt connect, or when ecu delivers it (and diode protects in that case)
The ABS ECU should certainly enter into the diagnostic mode (when the fuse is inserted) in the case of a faulty input sensor and tell you which sensor is bad. That's the whole purpose of its diagnostics. The fact that the ECU does not "self energise" by activating the main relay suggests problem within the ECU itself. Or it could be just a bad contact in the ECU pin (pin 8) that supplies +12V to the main relay. Have you checked the pin 8 condition and the continuity of the wire from it to the relay? Other things: are your relays 186 and 182 the original ones? They are a bit special as each of them has two diodes inside. To test these diodes, you will need to open up the relays.
I believe that you have already checked that the right relay colours are at their right places. Just in case, see my markings: Image Unavailable, Please Login
I have tested wires, relays seems to be original. Theres some diodes in those. I havent physically opened those those but i have tested all those relays with 12v, continuity and current pathway wise. I have tested all solenoids also. I opened ecu and nothing obvious by eye is visible. I have wigled the ecu connector with no results. Pump operates and relay 182 seems to work logically. But then again, i could have been missed something pretty obvious, doubt it tho
I will doublecheck those colours, but you cant install those relays wrong becouse they dont wrong sockets
Bench testing of relays with a 12V battery: GREEN - should click in both orientations of "+" and "-" on its pins 85 and 86 BLACK and YELLOW - should click only when "+" is on pin 86 (and not in the opposite orientation)
You also need to test continuity between 30 and 87a on the Green and Yellow relays when not energised. Sometimes these NC (normally closed) contacts can lose continuity due to corrosion combined with much smaller pressure between them as compared to the NO contacts that are slammed together. If you see some resistance (or lack of continuity) between 30 and 87a, you should remove the relay covers (easy with a small screwdriver) and inspect and clean the contacts.
Yes, those are also tested. I still need to test fluid level sensor circuits and check warning light wiring behind cluster, other than that i cant understand what else to test. But i have a feeling that even if theres faulty fluidlevel circuit, it would not paralise warning light? And also ecu pin 8 operation is a mystery, when it suppose to get powered? What i also have noticed is i have pretty weak accumulator, as i only get 3-4 pumps and motor kicks in
Well, since all relays and the diode block test ok, and the relays are correct type and in correct positions, the fact that you still cannot enter the diagnostic mode and the ECU does not send power to Pin 8 suggests a bad ECU. You should be able to find a used 348 one for a reasonable price but whether it is good or not could be a gamble. As for the ABS pump motor activation, 3-4 pumps does not seem bad to me unles you have info that it should be more than that.
Ecu fault seems evident. Someone has opened it before becouse the sealing tape on top of case screw had been damaged
Here's a reasonably priced one: FERRARI 355 ANTISKID ECU FERRARI ABS CONTROL UNIT 148838 FERRARI 355 ABS ECU | eBay (I have bought a number of parts from this seller, no complaints).
Miroljub, can you tell us what the function of the "Diodes Box" is in that system? It seems to tied to the Warning Light in some way, but the diodes seem to be back to front. http://www.members.iinet.net.au/[email protected]/Ferrari348/Ferrari348ABS.gif
If you get bored, check some videos I did on the ABS system. The first one is this: https://youtu.be/B3RH5uTXrqI In the 2nd or 3rd instalment, I delve into the diode box and it's very simple repair. I also recall that if the ABS warning light is on all the time (as it was in my case) you can't pull diagnostic codes, but they do list some rather broad reasons in the manual that can cause the light to stay on
