Can not communicate with vehicle, using ISTA

[chrisshara]

Guys,

I have tried and tried and tried to troubleshoot this issue. I can only put about two solid days into my car before I have to reassemble my car to be able to use it. My vehicle: 9/94 prod 325iC

I have no communication with my vehicle. My ABS light is on and my SRS light is on. I have zero volts on pin #20 of the round data link connector under the hood.

When I put two days into my car trying to sort this issue, I can recall that I do not have any shorts to power (obviously since I have zero volts on pin 20) and no shorts to ground on the TxD circuit.

I had tried disconnectig modules to see if this bus worked like a twisted pair CAN Bus, CAN high, CAN Low. But no such luck. Since I can't connect to ISTA, all I have is schematics. I don't have any information on how this bus is designed

to operate, or how to troubleshoot this issue based on how this bus is designed to operate. I "believe" in those two days that I had confirmed all powers and grounds to all or most of my modules. It has been awhile since I went at this issue.

I DO have Identifix. And there is a confirmed fix where a tech had no communication with the vehicle and the ABS light was on.. ...(4) confirmed fixes for a faulty ASC control unit.

Before I go and throw a ASC control unit at the problem. I'd like to try to diagnose this and confirm the ASC control module is bad, so that I don't waste $100 on a used ASC control module. And if it isn't the ASC control module, then yeah. I'm

still left hoping someone is familiar with how to troubleshoot the TxD, RxD bus.

Is it possible to hack this network or share voltages just to be able to communicate to diagnose ? Maybe I could read faults via. a hack and get codes from ASC and

the ASC codes might tell me that the ASC module is bad ?? I was hearing that this bus is a "half duplex," bus ?? And that this bus does not communicate in both directions at the same time. If so, it was suggested that I might be able

to splice the RxD to the TxD and maybe be able to communicate ?? Has anyone done this as a temporary means to communicate ?

Thank you all in advance.

[MParallel]

The first question would be, what kind of cable are you using?

[chrisshara]

The first question would be, what kind of cable are you using?

Using a chinese cable that is tested and known to be good. Even when I worked at the dealership, it would not connect with DIS / GT-1 using a yellow head or with ISTA and a ICOM/B with ICOM/C cable connected to ICOM/B. (authentic equipment). I have zero volts on pin 20 at the data link. I should have 5 to 12 v.

[MParallel]

I see, well then it's not ISTA that is the problem.

[chrisshara]

I see, well then it's not ISTA that is the problem.

Ha, Ha... ....I WISH it were that simple. But I have a feeling that guys who are computer guys, network guys, IT guys, electrical engineers, etc... ....will know of a hack so that I can manipulate the network to be able to communicate so that I can figure out the issue. Unfortunately, I am just a tech and a mechanical engineering student. Not a network, communications, electrical engineer, IT guy. This is not my area of specialty. And when ISTA DOES NOT comminicate.. .... information is VERY limited.

[MParallel]

Do wonder what cable. My yellowhead cames with all cables included.

[E36328Coupe]

ABS is an ADS module on my 95 car. Generic Vag com / OBDII / KKL won't speak to it.

Also is your 94 car an EWSI or EWSII as over there you all seem to have a car in the last half of the year and call it the next year model year.

- - - Updated - - -

Ha, Ha... ....I WISH it were that simple. But I have a feeling that guys who are computer guys, network guys, IT guys, electrical engineers, etc... ....will know of a hack so that I can manipulate the network to be able to communicate so that I can figure out the issue. Unfortunately, I am just a tech and a mechanical engineering student. Not a network, communications, electrical engineer, IT guy. This is not my area of specialty. And when ISTA DOES NOT comminicate.. .... information is VERY limited.

If you think your cable is good and it is a generic USB Vag COM / KKL / ODBII are you using a 20 pin to 16 pin adapter? Can you speak to the GM4 / ZKE?

[MParallel]

ABS is an ADS module on my 95 car. Generic Vag com / OBDII / KKL won't speak to it.

Also is your 94 car an EWSI or EWSII as over there you all seem to have a car in the last half of the year and call it the next year model year.

- - - Updated - - -

If you think your cable is good and it is a generic USB Vag COM / KKL / ODBII are you using a 20 pin to 16 pin adapter? Can you speak to the GM4 / ZKE?

See my sig pic

ABS works fine on mine without ADS on the M3. My 328i is ABS/ASC. That mixed module needs ADS.

[E36328Coupe]

Read my (previous) post

I have a 1994 325i on the drive and a 1995 328 with ABS and LSD, no AST, that modules needs ADS. In fact the first ADS interface I built did not work and I only got around to sorting it to fix my ABS

[chrisshara]

My car is 9/94 production and considerered a 1995 model year. My car does not have EWS at all. I do not know what ADS is. I assume LSD is a limited slip differential. ??? If LSD has another meaning, I am not sure what it is. Since my car is a 9/94 production there is no 16 pin OBD 2 connector. My car only has the 20 pin round connector under the hood. There is no issue with the ISTA or the cables, as I already had said that I have no voltage on pin #20 of the round 20 pin data link and I have tried (3) different BMW diagnostic systems that communicate with vehicles other than mine. I tested with ISTA (Chinese version), DIS / GT-1 with yellow head, and I tested with an authentic ISTA at the dealership using an ICOM/B with the ICOM/C cable to connect to the round 20 pin connector.

[MParallel]

ADS is the communication protocol that uses/need both the K and L line (RxD, TxD). Newer modules use a single bi-directional line.

Maybe I should say interface which use the above. ADS is Active Diagnostics Plug so is hardware.

[flyfishvt]

Do you have 12 volts at pin 14 and 16 with the ignition turned on? Without power to both you will not get proper communication.

I know you said you tested this ISTA unit on other cars. Were any of those cars e36s? Just curious.

Pin 20 is the K line. All modules use the K line. Its White/Violet. A limited number use both K and L line. There are several junction points on that K line where the K line from several modules come together. One is under the dash. It's a fin comb connector. The other is in the box that sits under the windshield cowl and houses the engine harness. Inside that box you'll find three White/Violet wires crimped together with a plastic boot covering the crimp. The fin comb connector is in a box with about 15 or 20 other connectors.

Also pull off the 20 pin diagnostic plug and make sure the wire is connected to pin 20.

[MParallel]

E36 modules ADS vs non-ADS (EWSII 96+ modules). Could be different for older cars.

ADS
ABS-ASC
OBC V
Kombi (instrument cluster)
Remote control module (not applicable to US)
CVM (convertible roof module)

Non-ADS
DME
ZKE/GM IV
Airbag
ABS
EWSII
IKHA (heater)
SMG
EGS (Autobox control unit)
Cruise Control
PDC (parking sensor)
Rollover sensor

[chrisshara]

Read my (previous) post

I have a 1994 325i on the drive and a 1995 328 with ABS and LSD, no AST, that modules needs ADS. In fact the first ADS interface I built did not work and I only got around to sorting it to fix my ABS

I am not sure what, "I have a '94 325i on the drive," even means. Not sure what to do with any of this information or how it helps or applies to me. Very sorry.

[E36328Coupe]

I am not sure what, "I have a '94 325i on the drive," even means. Not sure what to do with any of this information or how it helps or applies to me. Very sorry.

It's in reply to MParallel's incorrect information that the ABS module is not an ADS module. He told me to read his sig and I told him to read my previous post.

Clearly you have a 94 325 as do I and I have a 95 328, you think your car does not have EWS, so unless it has been modified chances are you have EWSI - drive away protection without a transponder chip such as in the EWSII 95 cars. The Euro 325 even has the US flash code feature (just not connected to the dash) I basically have your car with a wheel on the other side

- - - Updated - - -

E36 modules ADS vs non-ADS (EWSII 96+ modules). Could be different for older cars.

ADS
ABS-ASC
OBC V
Kombi (instrument cluster)
Remote control module (not applicable to US)
CVM (convertible roof module)

Non-ADS
DME
ZKE/GM IV
Airbag
ABS
EWSII
IKHA (heater)
SMG
EGS (Autobox control unit)
Cruise Control
PDC (parking sensor)
Rollover sensor

You do not have a 1995 car with ABS, yours also has the AST / TC - the normal ABS is an ADS module as per post #7 and #9

[chrisshara]

Do you have 12 volts at pin 14 and 16 with the ignition turned on? Without power to both you will not get proper communication.

I know you said you tested this ISTA unit on other cars. Were any of those cars e36s? Just curious.

Pin 20 is the K line. All modules use the K line. Its White/Violet. A limited number use both K and L line. There are several junction points on that K line where the K line from several modules come together. One is under the dash. It's a fin comb connector. The other is in the box that sits under the windshield cowl and houses the engine harness. Inside that box you'll find three White/Violet wires crimped together with a plastic boot covering the crimp. The fin comb connector is in a box with about 15 or 20 other connectors.

Also pull off the 20 pin diagnostic plug and make sure the wire is connected to pin 20.

The other cars I tested were not E36. But I did test on an E38 using the round 20 pin connector. So I know that my round 20 pin set up on my ISTA is, in fact, functioning. Yes, I do know there is a pin in the pin #20 location of the data link and I did test every single pin in the data link, and they all pass ther respective tests... ....except for pin #20. Worked at the dealer as a tech since 2002. I was never trained on E36. So I have no literature to read on body electronics / engine electronics, etc... of this era.

So yes, I do have 12 volts on pin #14 and pin #16 with the ignition turned on. But even with the ignition on, no voltage on pin #20.

I'm family with the brick of splices under the passenger side near the micro filter door. We nicknamed those massive splice packs.... .."the comb."

I guess I just have to verify continuity throughout all branches of the K-line ?? I feel like a module is taking the bus down. It has been a couple years since I have had time to continue troubleshooting this issue. So it's very hard for me to remember where

exactly I left off. :-/

[E36328Coupe]

If you are using a 16pin to 20 pin adapter, as asked earlier, is the pin 20 connected internally to another pin?

[E36328Coupe]

OP regardless of all this back and to the answer may well be you can't use ISTA with E36 / ADS stuff without ICOM
Once that is out of the way, you can try and use a generic USB OBDII / Vag com / KKL cable with something like INPA BUT are unlikely to be able to talk to the ABS as on cars of that age it is an ADS module. on MParallel's later car it is expected it can be accessed with one but not on the older stuff.

You will see a list of things folk can and cannot access with a generic cable in post 1 http://www.bimmerforums.co.uk/forum/...lained-t85191/

[MParallel]

It's in reply to MParallel's incorrect information that the ABS module is not an ADS module....


You do not have a 1995 car with ABS, yours also has the AST / TC - the normal ABS is an ADS module as per post #7 and #9

Is it really that hard to read? Above the list I posted, It says this goes for EWSII 96+ cars. i.e. yours does not apply.

The ABS, as in ABS-only is NOT an ADS module. Since my M3 doesn't even have ASC (AST is not an BMW term, it's not US spec, it has an ABS-only module, which I can perfectly read out with my USB-OBD-20-pin cable. Again, in my, as listed EWSII 96+ context.

The ABS/ASC combo module on my 328i, which does have ASC+T (and LSD) can only be read out with my ADS setup.

Therefor, the info I listed is not only correct, it's also tried and tested.

[E36328Coupe]

Is it really that hard to read? Above the list I posted, It says this goes for EWSII 96+ cars. i.e. yours does not apply.

The ABS, as in ABS-only is NOT an ADS module. Since my M3 doesn't even have ASC (AST is not an BMW term, it's not US spec, it has an ABS-only module, which I can perfectly read out with my USB-OBD-20-pin cable. Again, in my, as listed EWSII 96+ context.

The ABS/ASC combo module on my 328i, which does have ASC+T (and LSD) can only be read out with my ADS setup.

Therefor, the info I listed is not only correct, it's also tried and tested.

Is it really that hard to read? I have a 95 328 with ABS which can only be read with ADS. End of Your later M3 being readable is not relevant. I would not have built a working ADS interface if I could read it without (as already said, but apparently not read)

Oh, and that list also doesn't apply to OPs car either so no point posting it

[MParallel]

Is it really that hard to read? I have a 95 328 with ABS which can only be read with ADS. End of Your later M3 being readable is not relevant. I would not have built a working ADS interface if I could read it without (as already said, but apparently not read)

Now you're just repeating what I've been saying all along.

[E36328Coupe]

You can't contradict me and be agreeing with me

............The ABS, as in ABS-only is NOT an ADS module. ...........

Yes it is on a 95

[chrisshara]

OP regardless of all this back and to the answer may well be you can't use ISTA with E36 / ADS stuff without ICOM
Once that is out of the way, you can try and use a generic USB OBDII / Vag com / KKL cable with something like INPA BUT are unlikely to be able to talk to the ABS as on cars of that age it is an ADS module. on MParallel's later car it is expected it can be accessed with one but not on the older stuff.

You will see a list of things folk can and cannot access with a generic cable in post 1 http://www.bimmerforums.co.uk/forum/...lained-t85191/

I can use my Chinese ISTA with E38 20 pin round connector successfully. So why might I not be able to use it with 20 pin round connector on E36 if I can with E38 ??

NOTED: I am located in the United States, and my E36 is a U.S. production. There is differences between European and U.S. production. It would probably be less confusing if those who are in Europe not comment, or take a look at how my car is wired. Since it seems like our cars have different EWS, different ABS and it's just making things argumenative and adding confusion. And if you wish to help me with my issue, why do I need to know about 96+ ?? Has nothing to do with my car. I don't have IHKA, I don't have EWS, I don't have a fully automatic roof. I don't have OBD2, I don't have MS41.1... ..there is plenty of differences.

[E36328Coupe]

Don't have EWS? http://www.e38.org/EWS.pdf

Anyway, happy to leave you to it, good luck. (also depends what year of E38 your kit was tested on)

[chrisshara]

Don't have EWS? http://www.e38.org/EWS.pdf

Anyway, happy to leave you to it, good luck. (also depends what year of E38 your kit was tested on)

My 9/94 325iC does not have EWS. The '00 E38 that I connected to using the round 20 pin connector does have EWS, and it does of course have the 16 pin OBD2 connector by the cup holder. But I used the 20 pin round connector on the E38 becuase I wanted to be sure my diagnostic cables, etc... were working correctly.