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First of all thank you for any info on this subject.
I have a 97 Land Rover Range Rover in the shop and I can't communicate through obd2. I checked my power and grounds at the dlc, and all were good.
From reading Diagrams on Alldata, this vehicle uses a k and l line bus system. I had pin 7 back probed which is the k line while trying to communicate with scan tool, and I could see packets of square waves that the scan tool was sending out, but only received a no comm error.
The question I have is, is it possible to have a faulty module that won't allow communication even though the scan tool sends out a good looking signal? I know the line isn't shorted out, because it rests close to battery voltage with no data on it. Should I try to unplug modules on the k line to see if comm is re-esstablished, or is there another test I could do.
I was trying to communicate with hvac unit, but I also tried the TCM, and the ECM. Just for testing purposes though, I was just trying to get power train codes from ECM.
I did also try four different scan tools with no comm on all of them.
I just sent the hvac unit to BBA Reman to test it, but I did see an interesting post on IATN where I could disconnect the k line at the obd2 port and the ecm and run an external wire to isolate the k bus.
im using bbb industries don't have all data. I only see the ecm not a tcm. and there is a splice in the abs module com wires. is that the same diagram you have? did you check powers and grounds at the ecm??
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