Can not communicate with vehicle, using ISTA

[chrisshara]

I guess I just kind of feel like you guys are telling me what your car has. .....But your car is not the car with the troubles. I'm the one writing in with the troubles. I'm happy to tell you what my car has, and that my car has exactly what the ETM says it should be equipped with here in the U.S. Telling me what your car has in the U.K. is not going to help me with my issues here in the U.S. with a E36 for U.S. specs and North American market. It's only going to confuse me, becuase some of the acronyms you are talking about, I don't recognize as acronyms from the North American market. So it's confusing to me.

[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.

I have continuity from the White / Violet wire at the ASC control unit to pin #20 in the diagnostic link. No shorts to ground and obviously having 0.30 volts, there is no shorts to power. All my signals in the data link connector are normal with the exception of TxD (pin #20). Very sorry it has taken me so long to get back. Whenever I try to even attempt any sort of diagnosis on this issue, I need to have about 3 hours of time to disassemble my car and make another go at it. This has been an extremely frustrating issue. So... weeks later I have taken another stab at it. Although my car is a 9/94 production and considered a 1995. Based on the wire colors at my ASC module. I am using the ASC +T schematic in the 1994 E36 ETM page 3450.2-00. I found that my ABS Relay (Red relay) was not clicking. I was not getting power at pin #33 or pin #2 at my ASC control unit. And the very first thing whenever a vehicle does not communicate, the tester always tells us to check all power and ground supplies to whatever control unit is not communicating. In my case... ...It's every single control unit. And I know that I should be able to unplug control units one by one and after removing a control unit from the circuit, I am to check to see if communication has been re-established. I did this years ago. And disconnecting each control unit one by one did not lead me to any clues as to which module would be suspect, becuase I never got communication re-established. This is honestly an issue that is stranger than the truth and does not make sense to me in terms of diagnostic approaches that are supposed to lead me to a reason why this is happening, per BMW diagnostic approaches with a bus issue of this nature. I understand that my car is very old and not the type of car that ISTA will automaticlly identify. But if I manually enter my VIN and go I and manually select to do a test on the DME only, it should communicate. But it does not. I am not simply relying on ISTA to automatically deciper my VIN. Becuase I am aware that on the older cars, ISTA will not do so.

Anyway... ..As to my ABS relay issue not clicking and providing power to the ASC module. It's not clicking becuase the ASC control unit is not sending a ground control signal from pin #13 to pin #6 on the ABS Relay (Red relay). Absolutley no clue why the module is not sending this ground signal. I have 2 ASC modules. Tried them both. Same scenario. I have 34-52-1-164-023 and I have the origninal 34-52-1-162-662. I provided my own ground. Got the relay to click and checked power at pin #2 and pin #33 and confiredm that I now had power at pin #2 and pin #33 and to the best of my knowledge I had all my powers and grounds at the ASC module. So I check voltage on pin #20 and it was the same @ 0.30v when it should be over 2v. I tried an ISTA session and nothing.

I feel like I have a component of the ASC or ABS system internally shorted and messing with the functionality of the ASC control module. But I am also going to confirm all amy power and grounds to all my other modules. Still does not make sense to me why I can't simply disconnect the problematic control unit and re-establish communication.

[E36328Coupe]

Put a thread up to see if any one local has INPA and an ADS interface and is willing to try it for you. An ADS interface will do ADS and non ADS modules so covers all bases.
If they have an E36 and can read their GM4 and instrument cluster it proves both OBD and ADS comms working, then get them to try yours. I know you have faith in your setup but as far as I can tell it has never been used on an old E36. While this may give you no benefit it could save you spending weeks if your setup is just not compatible.

[chrisshara]

But I have 0.30v on pin #20 of the data link connector and spec is to be at least 2v.

[E36328Coupe]

When you have two things that won't speak to each other a known good that will speak to an E36 is an excellent logical decider for elimination purposes otherwise oyu could be troubleshooting a problem that is actually the diags system for weeks.

[chrisshara]

Issue SOLVED: Referenced S.I.B. 34-01-96. Confirmed that TxD communication issues are diagnoseable in the same fashion as CAN High and CAN Low. In that, disconnecting the module that is pulling the bus down will re-establish the voltage I was looking for to be able to communicate. In my case, disconnecting the IHKR module located below the center console pocket below the heater control panel got me 8.5v at pin #20 of the data link connector. I read online that spec for pin #20 is to be another over 2volts but not full-on 12v. Which is a major improvement over the 0.30v I have when the IHKR control unit is plugged in. I have heard that ISTA has glitches with older vehicles and that I might need a GT-1 simulator / emulator or some simulator. [??] But let's face the facts... ...if you got no voltage because a module is bringing down the bus, that is its own separate issue in itself. I will keep you guys posted on if my ISTA will communicate as is, no simulator etc... with my IHKR unplugged.

[chrisshara]

When you have two things that won't speak to each other a known good that will speak to an E36 is an excellent logical decider for elimination purposes otherwise oyu could be troubleshooting a problem that is actually the diags system for weeks.

Ok, So I now have every signal I need at my data link connector. 8.5volts on pin #20 is much better than 0.30volts on pin #20, and now my LED on my head lights up as well. Which is also a great sign. However, I still am not able to communicate and NOW, I will agree with you that I AM, in addition to my car troubles, experiencing difficulties with my Chinese ISTA and or the cables. I do NOT have access to another older BMW to test. I DO have a friend with the exact same Chinese ISTA that I have. He has his own cables. He has a 2005 E46 330i ZHP. Not sure spot to continue with my Diagnostic software issues ?? Should I start another post in "diagnostic software," section ??

UPDATE: a friend of mine has what is called a GT-1 simulator / emulator on his ISTA. I am going to try a scan with his equipment. I will report back.