How To: Modify a VAGcom KKL Cable for use with your BMW

[jthomsit]

Thanks guys,

Using EasyDisv44 I've now got that working with my unmodded VAGCOM. Again not quite sure why it wasn't working before (using Fister protocol in the 'touch screen calibration' setup) - autodetect obviuosly still doesn't work.

Though for some reason, can't read DME using either DIS or INPA, strange!

Just to add to previous post, my VAGCOM also has pin 16 connected to something on the OBD side. Wasn't showing up before, possibly bad solder joint...

[David Mc]

You need to jump pins 7 and 8 on your interface, the unmodded VAGCOM interface only uses the K line and you need to use the L line to wake up your DME.

[jthomsit]

Thanks David MC,

My OBD->20pin round does not have a pin 8 on it. So I can not see the benefit.

From what I've seen, instead the 20pin adapter has pins 17 (TXDII) & 20 (TXDI) joined together. Does that perform the same function? Or am I missing another wire entirely? Where should pin 8 on the OBD terminate on the 20 pin round? The other connected terminals are:

RXD (round pin 15) -> OBD pin15 (L line?)
power (round 14) -> OBD pin 16
GND (round 19) -> OBD pin 5 & 4


Thanks

[David Mc]

Pins 17 and 20 of the round 20 pin connector are both K lines, 6 cylinder BMW's use pin 20 and some 4 cylinder cars use pin 17 for TXD. The L line (RXD), which is pin 15 of the round 20 pin connector is already connected to Pin 15 of your VAGCOM unit. If you don't have pin 8 on the 16 pin OBD plug, I guess the option would be to bridge pins 17 & 20 on the 20 pin plug.

The bridging of K Lines is normally a standard feature on Carsoft interfaces.

[joako]

jthomsit, you can't read the DME but what about the EGS?

I think I have heard connecting the other pin on the OBD-II as well. There should be 2 K line and 1 L line. I would double check pin 8 is l-line, I thought it was 2nd K-line, but the point is try to connect the other one.

But it is odd you can talk to everything EXCEPT DME, usually it is the other way around.

[David Mc]

Thanks Joako, you are quite correct, pin 8 is the second K Line. Post edited accordingly. Some BMW V8's use 2 DME's, so this could be the reason that this car requires the K line signal on pin 17 of the 20 pin connector.

[jthomsit]

Thanks guys,

If pin 8 is connected on the OBD connector, where should it terminate on the 20 pin round connector? Are you suggesting I separate out 17/20 on my round connector and connect one to pin 15 OBD, and join the other one to 15 (round)?

I can't verify the accuracy of this but here's one of the diagrams I've been working on (courtosy of minsk555.narod.ru)


It shows
17/20 (round) -> k-line -> 7/8 (OBD)
15 (round) -> l-line -> nothing (OBD)

And yes, my 750 has two DME's Greedy I know I'll also check EGS tomorrow morning (UK)

Thanks for your time!

[David Mc]

These are the connections you need:
OBD Pins 4 & 5 ---> Pin 19 of BMW 20 pin connector (Ground)
OBD Pin 7---------> Pins 17 & 20 of BMW 20 pin connector (K Lines)
OBD Pin 15 -------> Pin 15 of BMW 20 pin connector (L Line)
OBD Pin 16 -------> Pin 14 of BMW 20 pin connector (Power)

If your interface only had pin 7 of the OBD connector hooked up to pin 20 of the BMW round 20 pin connector (i.e. only one K line connection), you would need to connect it to BOTH pins 17 AND 20 (i.e. both K lines). This is why we suggested you bridge pins 7 and 8 of the OBD connector as normally one K line is connected to each pin. Since you have no pin 8, pins 17 and 20 are bridged at the Round BMW 20 pin plug. A dodgy soldered connection to pin 16 of the OBD connector is definately a problem.

[jthomsit]

I'm sorry, I obviously haven't been clear. What you have described is exactly what is wired up. So thanks for clearing that up and ruling that one out.

And I can confirm that the EGS did respond (found some pictures I took of the DIS screen)

Other strange behaviour is that the IKE only responds when I select a later model year (was just experimenting) so i guess it could be a later dash that was retro-fitted to sort dodgy pixels.

Also the EML only seems to respond sometimes and not everytime. The DME has never responded.

Thanks!

[ferpe]

Basically everything is said, but here a link to a site which has a 100% compatible interface and the explanation + schematics over the BMW mods (from the GT1/EasyDIS installation thread):

http://forums.bimmerforums.com/forum...1297683&page=6

I have build this guys interface after a BMW diagnosis wizard in Germany (MALIBOO building his own diag software for BMW!?) said it was the one to have, it is 100% compatible with INPA and DIS (acutally with EDIABAS STD:OBD) and the modifications to a standard OBDII serial KL interface are clearly described on the selfbuild site (english a straight babelfish translation of his german pages but you'l understand).

http://66.163.168.225/babelfish/tran...kw-interf.html

The guy also sells the build kit for 15 Euro in his shop (link on the site). Here how a true KL interface looks (work for std OBDII serial dianosis software (not ELM type software)):



Please observe the 1-4 OBD reference is for the internal connection card to the OBD socket, the schema below lists the corresponding OBD pins.

Here the mods a std OBDII serial KL interface needs to have to be BMW diagnosis compatible (works also with BMW scanner demo, would assume Carsoft would also work but have'n tried it as Carsoft doesn't bring anything when you have INPA/NCS and GT1), as modified schematic and in words:



Here the mods it has over the std interface above:

1. pin 7 and 8 of the OBD interface connected
2. uses DTR instead of RTS (pin4 on sub D RS232)
3. Pin 1 of OBD is connected to DSR (pin 6 of a sub RS232) over a 1k resistance (for shorts protection)
4. RS232 RI (pin 9 of sub D RS232) is connected with OBD pin 16 (+ battery feed to detect battery signal) over a 1k resistance (shorts protection, the diod is polarity protection).

Hopes this can help someone.

[hanssae]

My cable with the FT232RL wouldn't always accept the programming, so I ended up just shorting a few pins low (to ground) since RI# and DSR# are already inverted. See pictures and descriptions here.

Hi KeifR,
Did you connect pins 7&8 at the obd connection aswell ,
or just grounded RI# and DSR#.
I am using FT232BL on a E65.

[TerraPhantm]

These are the connections you need:
OBD Pins 4 & 5 ---> Pin 19 of BMW 20 pin connector (Ground)
OBD Pin 7---------> Pins 17 & 20 of BMW 20 pin connector (K Lines)
OBD Pin 15 -------> Pin 15 of BMW 20 pin connector (L Line)
OBD Pin 16 -------> Pin 14 of BMW 20 pin connector (Power)

If your interface only had pin 7 of the OBD connector hooked up to pin 20 of the BMW round 20 pin connector (i.e. only one K line connection), you would need to connect it to BOTH pins 17 AND 20 (i.e. both K lines). This is why we suggested you bridge pins 7 and 8 of the OBD connector as normally one K line is connected to each pin. Since you have no pin 8, pins 17 and 20 are bridged at the Round BMW 20 pin plug. A dodgy soldered connection to pin 16 of the OBD connector is definately a problem.

Is it possible that he needs both k-lines hooked up independently? (Pin 17 to OBD pin 7, and Pin 20 to OBD pin 8?) If both DMEs need to communicate simultaneously, I'd imagine having the two lines bridged may lead to some issues

[PetarDurdevic]

I have a problem connecting my e36 328i. i have an obd to usb interface "elm327", and a obd to 20pin adapter with the preset as mentioned

OBD Pins 4 & 5 ---> Pin 19 of BMW 20 pin connector (Ground)
OBD Pin 7---------> Pins 17 & 20 of BMW 20 pin connector (K Lines)
OBD Pin 15 -------> Pin 15 of BMW 20 pin connector (L Line)
OBD Pin 16 -------> Pin 14 of BMW 20 pin connector (Power)

But it is not working??

Help??

[joako]

ELM interface won't work! That I know of ELM interface will only work with some generic OBD-II software that states its compatible with ELM. I think I've tried to use ELM interface with the VAG-COM software on a VW and it didn't work. You need a "VAG KKL" type interface.

Also these days you can just search "INPA" on eBay and get a cable that's compatible without any modification, a few bucks more last time I checked, but still around/under $50.

Also for E36 read up on that, you might need an ADS interface to access certain modules, especially on the early production cars. I know with certainty the KKL interfaces work with everything from E38 until DCAN was introduced.

[MarkoE46]

Hello everybody,

I've been searching a bit about vag-com kkl cables around here, and I've just found that some of you are using those cables with INPA with some modifications. Now, I'm looking on the Dealextreme site and I don't have a clue which cable is the right one (or is it just important that it's a vag com kkl calble?)

I need it for a E46 and MAYBE for a E39 (so no ADS for e36, no D-CAN, and so on, and sorry for shouting).

[joako]

E46 and E39 are electrically very similar, the answer is yes it will work.

But honestly if you are going to buy something go on ebay and search for INPA cable it should work 100% no mods.

[MarkoE46]

Thx for the answer
I've also been looking on ebay for those cables and I want use a kkl interface because:
1.) They are cheaper
2.) As I se, INPA cables need a "real" serial port, so i would need to source a usb-serial stick that has all rs-232 pins.

On the other hand, I don't have any problems with soldering, so I'm not afraid to do some modifications.

[KeifR]

Hi KeifR,
Did you connect pins 7&8 at the obd connection aswell ,
or just grounded RI# and DSR#.
I am using FT232BL on a E65.

Sorry for the very late reply.

I just grounded out RI# and DSR#, but that would only work on the RL, the BL is different for those from what I recall.

I did not have to short pins 7 and 8, because on an E65/E66 they are internally shorted (so you CAN short them on your cable if you choose, but you don't need to for this car).

[hanssae]

Thank you KeifR,
I tried the grounding , but i didn't work , so I have just done the transistor / resistor mod.
I have not tested it yet , but I have ordered this RL interface , just in case http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370453504187&ssPageNam e=STRK:MEWNX:IT

[vince59]

I am waiting to get mi IF from china (both COM and USB version) to give a try..for the time being set up is fine on three PC, two notebook ACER and TOSHIBA and one desktop HP....

[ogee]

Just wanted to let you know that I use a VAG-COM cable without modifications on my E87 120d (date 11/04). Tested OK with INPA and NCS Expert. There is of course no ignition detection.

The chip is an FT232BL.

[ptikkala]

i did the transistor mod on my obd cable, but didnt work so i opened up my obd-bmw round adapter and noticed that there are pins 14,15,20 and 19 connected, pins 20 and 17 are shorted. What i need to do to get the ignition recognition to work?

[vince59]

soorymistake

[vince59]

I started enjoying INPA with my VAG KKL in which I soldered together pins 7 and 8.
It works with both interfaces USB (with chip FTDI 232BL) and COM (with MAX232 chip)connection but I do not have the ignition and battery light black.
INPA is working but sometimes it does not find some modules so I wonder why. Is it a problem of the cable?
I have the battery and ignition signals white..do I need them black?
I am considering modding the interface with COM port using the transistor and the resistor, but I wonder what is the modding procedure for the USB interface.
Is it essential to have the battery and ignition sign black or they can stay white?

[geargrinder]

I started enjoying INPA with my VAG KKL in which I soldered together pins 7 and 8.
It works with both interfaces USB (with chip FTDI 232BL) and COM (with MAX232 chip)connection but I do not have the ignition and battery light black.
INPA is working but sometimes it does not find some modules so I wonder why. Is it a problem of the cable?
I have the battery and ignition signals white..do I need them black?
I am considering modding the interface with COM port using the transistor and the resistor, but I wonder what is the modding procedure for the USB interface.
Is it essential to have the battery and ignition sign black or they can stay white?

Most of the great DIY info around here for the transistor mod IS for the USB, and djcristi has a sweet one here for the BL that I in fact used to copycat my RL mod on:
http://forums.bimmerforums.com/forum...4&postcount=21

Yeah you need battery/ignition sensing to either be faked or work to get everything to work especially anything coding related as the software is super sensitive to power interruptions so it wants to know there's enough voltage to not have the module crap out in mid coding and brick it.

The Mprog/FTprog tricks are the fakery... And of course really working properly (aka actually sensing battery/ignition vs. faking it) is far and away the best thing.