W203 CLK 2006 Connectors X30\7 and X18\28 abducted by aliens ?

[hofnerpres1]

Hi. I'm busy trying to diagnose a lack of CAN signal at the OBD Diagnostic at positions 6 & 14. These two wires come from a connector shown on WIS wiring diagrams as X18\28 next to the CAN collector "strip" X30\7 both in the LHS sill area. I can find every other connector except these two. They aren't hidden by the TCM either. I'm used to the factory wiring diagrams going a bit "vague" especially on late production models and they often don't keep up with the frequent minor changes on the shop floor. However there are enough parts littering the garage floor already so has anyone else hit this one before ?

 

[LostKiwi]

Check the right hand side. Not unusual for diagrams to refer to LHD cars and be mirror imaged in part on RHD cars.

 

[DREAMER NO2]

Some carts dont have them ,, its not the first time i have red about them missing .

 

[hofnerpres1]

Many thanks for the replies. I think you have both nailed the problem. A happy hour or two has revealed that Mercedes WIS and EPC is very Left Hand Drive centric. RHD variations get some mentions but when it comes to "what goes where" diagrams there are only misleading LHD versions - since UK are a small market percentage it was probably a simple commercial decision. This is sad since some connectors have been moved over - the proximity of the differently placed EIS and steering wheel etc made that sensible but others are as per the LHD picture. A real mix up. It's looking like CAN BUS "strip" X30\7 has been done away with and the circuit simplified. The other big junction strip is a the CAN C X63\4 which has made the leap over to the RH sill. All clean with good signals and a good ground. This leaves the hunt for X18\28 which feeds the missing OBD signal so has to be found. Clearly could be any damn place. Don't miss next weeks exciting episode....

 

[DREAMER NO2]

Bring it on ....

 

[hofnerpres1]

Thankfully - mystery number one solved - Only a few more to go. The wiring diagram suggested there is only one connector with two GN & GNWH ins and outs. Why they used something so big is a chuckle but it beats fiddling with all the other micro nail busters. It's on the RHS door channel ( German translation - LHS) and looks thus :



This allowed me to trace it back to the EIS - it has a dedicated socket for this diagnosis circuit and is on the top RHS of this picture :



The plug is not the tightest fit and I must have dislodged it when refitting the switch which is a fiddly pain. With sanity restored we tried to connect the iCarsoft scanner again - no change - ECU and TCM access only which are on a different Can C line coming from the blue plug. When tested there is no voltage at the diagnostic output and high transient impedance which suggests we're looking at a gateway interface ? Any comments welcome. ( The warranty sticker story could fill several pages since they had the car modules for eight weeks - lets hope it's not still faulty ). Any readers still awake can get back to the main saga under W203 A209 No Crank - No Start.

 

[hofnerpres1]

For some reason the iCarsoft V1 scanner did the job once the engine was running - works really well and confirmed all the modules were happy and the pressure switch on the brake working well at 1 to 48 bar. Looks like it made a digital handshake and now also works with engine off and ignition only. Result.

 

[LostKiwi]

All scanners need the ignition on.
If doing prolonged diags best to fit a charger to the battery to prevent spurious error codes.

 

[hofnerpres1]

Thanks LostKiwi. The problem was that initially the scanner didn't read with the ignition on - engine off. Once it connected with engine running it discovered how to do the job without. It is interesting how quickly voltages can drop when you spend a few happy hours searching for electrical gremlins. I have a small wall mounted automatic trickle charger that keeps me topped up.