96 LS400 - "OE Level" Scan tool - No Communication

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New Member
I have an Autel Maxisys MS905 diagnostic/scan tool. It will communicate fine using generic OBD2 J1850-VPW, but if i try to connect via the actual Lexus specific menus to get OE Level data/tools it will not communicate. I am assuming you have to go through one of the other 2 diag ports (rectangle one under hood and round one by obd2 port) since it is on a bus that connects to many modules and not just the ecm like the obd2 port does (see attached diagram). Does anyone know what E1, TC, TD, A/D, A/C, etc. stand for on the other diag connectors. If i could figure out which lines are what and what protocol is being used i can make up an adapter.

EDIT: I have also purchased a knockoff VCI for techstream and cannot seem to get it to communicate either.


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Well-Known Member
Hamilton. New Zealand
E1 - earth, TC - trouble code, puts modules into diagnostic mode, A/D auto drive - from cruise control ecu, a/c from air conditioning ecu. DLC1 and DLC2 don't have an ecu communication line on an obd2 LS400. Early OBD1 ecu use TE1, TE2, E1, W, ECT and ENG (VF1) on underdash port. Underbonnet doesnt offer comms with scan tools on all models. If generic OBD2 is communicating then none communication of model specific generally means either incorrect year chosen or the scan tool isnt using correct protocol. The last of the non vvti swapped around a bit making it lots of fun.