CAN Bus

Look for any wires that are spiralled together(but not speaker wires LOL). Those are you can lines.

 

they are linked together by a white and green whire, you will find a plug close to the ecu either end.

 

FBB, on ODB II equipped cars shouldn't you be able to trace the CAN bus wires back from pins 6 ( CAN high) and 14 on the OBD connector? But I suspect you already thought of this and it didn't work.

 

FBB, I'm trying to diagnose a CAN issue on a '99 456M. According to the factory manual, pins 6 and 14 are populated on the OBD II connector. Pin 4 is chassis ground and there is a Ferrari bulletin about shorting pins 4 & 5 together to provide a signal ground on pin 5. This car has had that rework completed. However, I'm not seeing an expected <5.0V digital CAN bus mirrored signals? I see roughly constant 9.0V DC on both CANH and CANL? That might be what's wrong with this vehicle, but have to do further diagnosis to confirm. Has anyone confirmed that true CAN signals are available on pins 6 & 14 of the diagnostic connector?

 

Sounds familiar I have a 99 456m I was looking at having a can error also if you want to swap notes call me Adam 203 770 1695 Im interested and im not done with it yet. I don't feel like sharing with non professionals by writing to much on this site. I was looking at the car with sd2 and an sd1
FYI not 100% sure but on older cars can is just for module to module comm (powertrain stuff) the scan tool is not privy to tap in till later cars 08 and up on older cars the scan tool is talkin k line or two wire tx rx stuff slow and old

 

Left you a voice mail.

 

Is this of any use to anyone ? (pinouts from a standard configuration OBDII connector)
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Also, the handheld readers won't do this, but if you are using a PC-based scantool with associated data processing software (I use the Gendan package, myself), you can select an option to force it to connect to the car's ECU using only the CAN protocol (regardless of whether that is / is not the default protocol setup for your car's ECU). Then the software will identify and indicate (display) which particular pin locations are supplying the main PID info --- in that way, you can then know which pins (and therefore, which wires) are carrying the CAN signals for any particular manufacturer's configuration.

 

Fatbillybob: Picoscope makes USB scopes for use with a laptop. I have model 2203 and it was only $260 and it will decode can signals. It has two channel inputs but I have to admit that I haven't got to that project yet (rod knock on the TR and 911 molested by professionals to fix first). There is a document on Mercedes CAN system with lots of information somewhere on the internet and the Elector website has a good book on CAN systems: Controller Area Network Projects by Dogan Ibrahim. FWIW.

Jeff Pintler
89 348tb, 86tr, 99 360 3-pedal

 

Jeff. Thanks, yes I have a 4 channel Picoscope. You can determine if the CAN BUS signals are online and if the bus is running, but that's about it. If a module is creating a problem for the bus, you can usually find that through process of elimination. BUT, you can't actually see what data is being sent. For that, you'll need a CAN Bus sniffer interface tool, such as a Kvaser Leaf (have one of those too). But then, you'll need a software package to monitor the bus and interpret the messages. This is more difficult and expensive. Truly useful software packages for isolating misc OEM CAN messages runs thousands of $$. There a couple of free programs that can give you some picture of whats happening, such as CANKING (Kvaser), and Pisnoop (PiSnoop - Pi Innovo) demo version. A product called VehicleSpy is a great CAN tool, but $$$$ for the hardware and software.

 

As an update to my earlier posts, I believe the 456 in question is now fixed. During the engine change, part of the O2 sensor harness was damaged. Technicians identified and bypassed 2 broken wires previously, but missed a third open return line on the Bank1 Post Cat sensor. The sensor worked, but erratically with a floating ground, but eventually would look like a bad sensor or cat and set a code. Had to disconnect everything and pin out the harness with a DVM one pin at a time to find it. The CAN Bus P1625 DTC code still pops up from time to time, but is commonly found on other cars we tested as well, and does not set the MIL.

 

No you only fixed your o2 and cat fault codes wich no one on this thread even knew you had
The easy stuff is fixed but the can fault is not solved

 

NEAD,
Yeah, I guess the whole story isn't clear. This 456 experienced an engine failure at low miles which was covered under warranty by Ferrari. After a complete engine replacement by an authorized dealer, the vehicle ran fine, but would consistently set the Check Engine (MIL) lamp after 100 miles or so of driving. The vehicle was then sold and an independent dealer purchased it, figuring he could have it repaired. However, it wasn't that easy. A Ferrari dealer was unable to fix it, as were two other independents. The O2 sensors were replaced multiple times during this process. One of the sensors was working, but with a floating ground that was causing erratic results. The bad ground was difficult to isolate (made even more difficult to track down due to a lack of any published schematic wiring diagram for this car...only connector/wire color lists). However, whenever diagnostic scans were run, P1600 and P1625 codes were also reported (in addition to other 02 and catalyst related codes), which relate to CAN bus and serial communications. We determined the CAN bus had proper termination impedance, and the data transmission signals were visible, working, and appeared within normal limits via Picoscope. We did not have software available to actually read the CAN bus words being sent and received, but each of the three modules on the CAN bus (two Motronics and the Transmission Controller) reported their addresses correctly on the diagnostic scans, which indicated that they were communicating properly with each other over CAN. Another 456 was tested, and produced the same 1600/1625 codes and CAN signals with no known problems. Contact with a FNA technical source revealed that these codes are commonly seen, and are not necessarily an indication that a problem exists. Unless someone has additional knowledge about the 1600/1625 code specifics, we're assuming they are unrelated to the MIL lamp issue. The car is now being driven to test if the MIL comes on again.

 

Hi everyone
I have problem in f12 on drive all lights coming on cluster after that vehicle not started off the ignition then start I checked can and bcm but can't figure out

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