General Question about System Readiness Tests

[Charles]

This might be a stupid question, but please indulge me.

I'm curious about the "Ready" status and exactly what it means. I understand that it's not ready for an emissions test until all the components show "Ready", but why the word ready (unless it means only that it's ready for testing at an emission station)?

I was told that a DTC related to a particular component/system won't be set until that component/system shows ready, but I'm not sure that's true. Isn't it correct that a DTC can be set even while a component shows "Pending"? If so, after the test completes, will it then switch to ready despite the fact that the DTC was set (and MIL illuminated)?

[Chevy366]

This might be a stupid question, but please indulge me.

I'm curious about the "Ready" status and exactly what it means. I understand that it's not ready for an emissions test until all the components show "Ready", but why the word ready (unless it means only that it's ready for testing at an emission station)?

I was told that a DTC related to a particular component/system won't be set until that component/system shows ready, but I'm not sure that's true. Isn't it correct that a DTC can be set even while a component shows "Pending"? If so, after the test completes, will it then switch to ready despite the fact that the DTC was set (and MIL illuminated)?

From what I have seen a "pending" does not trigger a DTC event until all parameters are satisfied, either the necessary parameters are fully met and triggers a DTC/MIL or they are not fulfilled and the "pending" status goes away.

Someone else will have to chime in about the SRT (System Readiness Test), I would think that the same would be true with it, the parameters must be met to satisfy the test and then triggers a "ready" event, until that happens I would suspect that without the "ready" status it would not trigger a DTC/MIL event.

[Charles]

With the SRT, I thought Pending means that it hasn't yet run that particular system/component's test. Once it does then it switches to Ready, no? However, Ready for what exactly? If all it means is that the tests have, or have not complteled, maybe it should be more aptly have been labeled "Not Complete" and "Completed" instead of "Pending" and "Ready". That makes me think there's more to it...

Also seems to me that if a SRT system is state of Pending and won't switch over to Ready until a particular system/groups's conditions are met, a DTC/MIL could still be triggered as soon as a specific item in that system/group if it has failed.

[Charles]

Oh wait, maybe it differs for continuous vs non-continuous monitors? Maybe with non-continuous events, the only time an associated DTC/MIL event is tested is during that system/group's test period such that they won't ever trigger if that individual test isn't being run (such as with a Pending status)?

[joecar]

ready = all the tests for this monitor have run (regardless of the pass/fail state of each test);
pending = not all tests have run yet (some scantools call this not-ready);

each monitor includes a set of tests each of which is linked to some DTC;
some DTC's are linked to specific mode $5/$6 tests, while other DTC's have their own other specific tests;

each non-continuous monitor is run when the conditions for this monitor are met;

the continuous monitors are always run (which is why these 3 monitors are always ready);

if a monitor is not supported, then it will by ready by default (it has no tests left to run).

[Charles]

each monitor includes a set of tests each of which is linked to some DTC;
some DTC's are linked to specific mode $5/$6 tests, while other DTC's have their own other specific tests;

Thanks joecar. I'm a bit confused in that I thought all the SRT stuff, being emissions related, was linked to mode $5/$6 tests (or at least the test results can be found there). If not then how can one know the specific value of the test (not just pass/fail)?

if a monitor is not supported, then it will by ready by default (it has no tests left to run).

This brings up another question regarding my trying to help a friend out... if a SRT monitor is not supported then shouldn't it show N/A as opposed to ready? I ask this because a friend bought a suburban from a local auto auction that was missing its ecm (not sure why this would be, but it lowered the price of the vehicle dramatically). He bought a replacement ecm off ebay and I used a V2 license program it using my segments. I have a 2500HD truck (also with the L29) and when we looked on TIS the only segment that had a different ID was the engine one (it was only off by one digit). For kicks, and not knowing all of what we are doing, lol, we dropped it in and did a VATS disable and a crankshaft relearn. All seemed just fantastic until a few miles later when the MIL turned on. When I read the DTCs it was a single P0410 code (secondary air injection). It then hit me that his motor doesn't have an air pump (obviously mine does). Thus, I went back in and changed the DTC to not reported (left MIL set to on) and there doesn't seem to be any other problems.

However, my question is will he have trouble when he goes to smog it? I told him not to do anything until I investigate the software further. His suburban is bone stock and should pass an emissions test (all the factory equipment is there, and it came from the factory without an air pump (unlike mine)), but I don't want the computer detecting something wrong in the code (if they even do that, have no idea).

I have since noticed there's an option for disabling the SRT item called AIR, and also even another option that has notes about disabling it if you remove the air pump. Technically we didn't remove it, just never came with it, but since I'm using my code, it's probably like we removed it? Should I mess with these too? Again, the vehicle isn't currently (after the change) noticing a problem, I just don't want him to run into something with the smog station!

If I could get a copy of his factory ecm code, I would just program that up, but it's not on tunefiledepot so the next best thing was mine.

[Charles]

Just to be clear, if I plug the V2 into his suburban and view the SRT screen, it shows 'Air: Ready'. Should it show 'Air: N/A' instead since the pump was not available/installed from the factory?

[joecar]

Thanks joecar. I'm a bit confused in that I thought all the SRT stuff, being emissions related, was linked to mode $5/$6 tests (or at least the test results can be found there). If not then how can one know the specific value of the test (not just pass/fail)?

...

Yes, correct, readiness monitors/tests are linked to mode 5 and/or mode 6 tests, each of which is linked to a DTC;

but also note there are DTC's that are not linked to mode 5/6 tests (e.g. a sensor performance/fault DTC) (of course, these are not linked to the readiness monitors/tests).

[joecar]

When a monitor/system is not supported, its readiness state is immediately "ready" (this is how CARB defined it).

[Charles]

When a monitor/system is not supported, its readiness state is immediately "ready" (this is how CARB defined it).

I'm not so sure this is correct. I know that I have seen other monitors that show N/A instead of Ready when the system wasn't installed from the factory (usually for AIR and EVAP on mid to late 90s vehicles).

Joe, do you happen to have the CARB document number or rule number for where this is defined. I just spent 20 mins on their website and there is a ton of stuff, but I couldn't find where this is laid out...

Also, I downloaded a stock 49-state segment from tunefiledepot and under Diagnostic Enablers, then Diagnostic Tests it has AIR set to No. I'm pretty certain that this will change it to "AIR: N/A".