Read DTCs on LS1B bench setup?

[DrX]

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.

[GMPX]

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!

[DrX]

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.

[joecar]

The LS1B has conditions that have to be met before some of the DTC tests are run... those conditions never happen on the bench.

[DrX]

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.