'Made in Franoe'

[HydroFreak]

I bought this interface for Diagbox/Lexia around 3 years ago from an eBay seller. It cost a little more than some similar looking ones and the seller mentioned that it had all the same chips or components as the genuine item.

I've used it from time to time for diagnostics on our 2007 C5 Hdi 2.0 and to re-set various things like the gearbox ECU when I put a new valve body in the 6-speed auto. It still tells me there are certain faults present but these don't seem to affect the car's performance and I don't have any warnings coming up in the instrument panel or dash top display.

The thing that has me curious is how close is this interface to the genuine item, and is it possible I'm getting oddball fault scan results as a result of it not being genuine? I run Diagbox on WinXP32, version 7.57

[HydroFreak]

I've just checked for that 10k resistor on the back of the bottom board and it's missing in mine - is it a good idea to add that resistor to my board or will it make no difference for a 2007 C5 like mine?

[GiveMeABreak]

I need to see the reverse of the circuit board of picture 3 to confirm.

As far as the faults go, can you list the actual fault codes you are getting, as these may be ghost faults. Can you confirm your VIN (PM it if preferred) so I can check exact options and I might be able to throw some light on these.

[HydroFreak]

Thanks very much for the offer to look into it Marc, my VIN is VF7**************[VIN obfuscated, can be read by forum staff]*******

I'll just post faults one at a time.

Fault P05D2 is the most common one - SWAS showing bad in Suspension ECU as follows:

[HydroFreak]

Bottom board underside - I've circled where the 10k resistor is apparently missing, I think?

[HydroFreak]

Here are the other two that I wonder might be a ghost fault?

"Switch module under steering wheel"

and

"Pre-post heating relay circuit plugs never supplied" P1351

[GiveMeABreak]

It certainly looks like it, see the picture I posted here:
viewtopic.php?f=51&t=59785&hilit=10k+resistor#p570919

Just looking at the code now....

[GiveMeABreak]

Ok, so I'm glad you posted that last snapshot of the faults, as it provides me with more info.

The SWAS needs to pass its info to the Suspension ECU - but I note that there is also a problem with the Switch module under the steering wheel, where the SWAS is located. Added to this, there is also no dialogue with the ESP / ABS system. The ABS / ESP ECU is one of the areas where a non-full chip VCI can have problems communicating. The ESP / ABS ECU also talks to the suspension ECU. These issues may all be related as they are interlinked.

Without getting full communication and dialogue from all the ECUs, it would not be prudent to start diagnosing whether there are any problems. Normally if there is any issue with the ABS, like a sensor failure, then it will knock the whole ABS / ESP system out and will deactivate the safety features by going into a backup mode, providing braking but no ESP and no ABS until it is resolved (for safety reasons).

This would normally illuminate the ABS warning on the dashboard for a malfunction. If this has not happened then it may be working perfectly - but the diagnostic cannot communicate with it. Again, the same is true of the SWAS - if this is actually out of adjustment or is not working, then it will also deactivate the ABS / ESP as this system relies on the info from the SWAS to determine trajectory, speed and angle of turn etc.

So normally in the case of a SWAS fault - a calibration would normally be undertaken first, assuming there is power to the sensor and it is operating. The angle of turn in degrees can be seen within diagbox if it is working and the procedure can be followed to calibrate it.

But again looking at the fault list, the SWAS has dialogue - but cannot understand what is going on - this may be VCI related if it can not communicate with it. We know that the 10k resistor affects CAN communication on some vehicles including the C5 and can cause comms / dialogue issues if missing. So we may have a problem in determining if there is an actual problem as it it being compounded by the VCI issues. Ideally, I would suggest locating another member with a C5 that has a working VCI to undertake a global test with and see what that reports back for a comparison first. As for the Glow plug fault, I would ignore that for now - I have always had this on all my HDi C5s. The glow plugs are rarely used on HDIs, except in extreme low temperatures and sometimes (only where commanded by the engine ECU) to assist with particle filter regeneration - so can generally be ignored unless there are related faults.

[HydroFreak]

Thanks Marc, you've confirmed my suspicions, i.e. that the VCI is possibly not reading correctly. I'll try to locate a fully working one and run the same scans on my car. Failing that I'll stick a 10k resistor in it and see if anything changes.

[GiveMeABreak]

Ok, let us know how it goes.

[Paul-R]

Is it known exactly what the adding of the 10k resistor alters/fixes?

[GiveMeABreak]

When the software queries the state of this particular input pin on the microprocessor, it doesn't know if it is pulled to VCC (high) or to Ground (low). Using a 'pull up' or 'pull down' resistor will ensure it is in one state or the other and uses a low amount of current.

On the board, the 10k resistor is a 'Pull Up' type.

In the case of the VCI, the resistor is placed on the CAN line from PIN P94 of the MCU, through the logic unit HA08 and onto the Optocoupler. CAN and Full CAN systems may have difficulty communicating without this resistor in the circuit.

As you probably know CAN has varying protocols and uses High and Low speeds, with the critical systems like ABS, Engine, Gearbox and Suspension on the High 'Priority' speed and other systems like comfort, lighting, heating on the low speed, low priority. Many who do have trouble communicating with one or more ECUs like the ABS system may be as a result of the missing resistor - again depending on the CAN speed, protocol used, and on the electronic architecture of the vehicle.

Some without full chip kits have tried soldering in the resistor and it has made no difference - but this is likely to be because there are other missing components too. It is often cheaper and easier to buy a full kit in the first place if you are having issues rather than trying to rebuild one with missing parts.