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If anything, Chris, it's the opposite.
A failed/failing CPS rarely sets a code and there's a good reason. It's also why so many of us can't instantly diagnose a bad CPS. In order to detect a missing rpm signal, the ECU and ignition control modules need to know the engine is actually turning over, otherwise how would it know it's missing. The only way it can do this is by having a pulsed rpm signal from the CPS. There is no other reliable sensor or mechanism for the controllers to know the difference between a bad CPS and simply not turning over at the moment. In a no-start situation you might think the controllers would know the starter motor is running and turning the crank, but there is no such signal to the controllers so they have no way of knowing.
Now as for the missing rpm signal OBD system DTCs, you now have to ask if it can't figure out a bad CPS then under what conditions do these codes get set.
For the 1-3-1 code "Ignition system RPM signal missing" on port 2: The rpm signal gets passed from the CPS to the ignition control module then to the ECU. This DTC is normally set if there is a wiring/connector fault between the ignition control module and the ECU or if there is an ignition control module failure. Both are rare. As there is minimal other handshaking between the controllers, I've always assumed this code only happens when the rpm signal suddenly goes missing while running, such as being an occasional intermittent bad/faulty signal where the engine manages to recover and continue running to distinguish that from the ignition being switched OFF. You need to realize these controllers aren't geniuses and were designed in another era where everything was mostly A+B=C.
For the 2-1-4 code "RPM sensor signal absent intermittently" on port 6, a similar story applies. It needs to know the engine is/has been turning over. This code identifies the cause of a hiccup, not a stall or no-start. Note that it says "missing". Signal interference adding a mystery pulse doesn't qualify. Interference would have to be so bad as to mask an expected pulse, begging the question how did the engine even get started in order to know it can set a code.
The above story agrees with all the experience I've ever had with bad CPS rpm sensors. I've never had an rpm sensor code in the four LH 2.4 systems I've maintained over the past 34 years.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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