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Thread: Read DTCs on LS1B bench setup?

  1. #1
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    Default Read DTCs on LS1B bench setup?

    Is there a way to read DTCs on a LS1B bench setup? I can trigger and clear(V7.5 only) unknown DTCs, but get no DTCs stored if I try to read them. Should be plenty of them on a bench setup.
    2017 Camaro SS, 2014 Ram 2500 4x4 Cummins 6.7L, 2004 Chevy Avalanche Z71 4̶X̶4̶(now 2WD), 5870lb race weight, 10.93@ 124, Twin TVS1900s, Twin Throttle, 429 LSX, 4L80E, custom 14 bolt rear, V2, R̶o̶a̶d̶R̶u̶n̶n̶e̶r̶(dead), COS3......
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  2. #2
    Forum tyhee Site Admin GMPX's Avatar
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    You'd think so but I've noticed on the older PCM's they sometimes don't set any DTC's on the bench, late model stuff on the other hand you get pages!


  3. #3
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    Yes. Same result with HPT and with multiple LS1B PCMs. I can wire up a throttle/pedal/TAC and cause the throttle to disable by doing something that would set a DTC. It will re-enable if I clear DTCs. So the fault is definitely stored somewhere.
    2017 Camaro SS, 2014 Ram 2500 4x4 Cummins 6.7L, 2004 Chevy Avalanche Z71 4̶X̶4̶(now 2WD), 5870lb race weight, 10.93@ 124, Twin TVS1900s, Twin Throttle, 429 LSX, 4L80E, custom 14 bolt rear, V2, R̶o̶a̶d̶R̶u̶n̶n̶e̶r̶(dead), COS3......
    Gettin' the Groceries

  4. #4
    Joe (Moderator) joecar's Avatar
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    The LS1B has conditions that have to be met before some of the DTC tests are run... those conditions never happen on the bench.

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    Looks like the PCM needs to see a crank sensor signal after a battery dis-connect/re-connect before it will report any DTCs. Even DTCs whose tests run without the engine running. I simulated a 600 RPM signal on the CKP input, then I could read the stored DTCs. As long as I don't disconnect the battery for some period of time, I don't need to apply a CKP signal again...I can still read DTCs on subsequent Key cycles. I tried a 5 minute disconnect and could still read DTCs without applying a CKP signal.
    Last edited by DrX; May 6th, 2021 at 12:20 PM.
    2017 Camaro SS, 2014 Ram 2500 4x4 Cummins 6.7L, 2004 Chevy Avalanche Z71 4̶X̶4̶(now 2WD), 5870lb race weight, 10.93@ 124, Twin TVS1900s, Twin Throttle, 429 LSX, 4L80E, custom 14 bolt rear, V2, R̶o̶a̶d̶R̶u̶n̶n̶e̶r̶(dead), COS3......
    Gettin' the Groceries

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