Smog for Gen I -- Can't get RPM Reading?

[jayriddle]

Smog for Gen I -- Can\'t get RPM Reading?

Took the car in for California smog check, and two different shops were unable to complete the test because they could not get a RPM reading from the engine.

This has never been a problem before (even took it to the same shop that did the test last time), so I don't know why it's an issue this year.

Does anybody know what could cause this problem, and how to solve?

Thanks,
Jay R.
'94 RT/10

 

[dansauto]

Re: Smog for Gen I -- Can\'t get RPM Reading?

yes, I had the same problem on a dyno. They are requiring Smog checks on obd1? wow that *****. if they are taking it off a plug wire, try a differant wire. If they are taking it from the scan tool then check then I am not sure why they could not get a reading. The crank and cam sensors both set timing based on RPM so if your car is running then the sensors are working-it must be the output on the PCM is not working (maybe clean the connctor)

 

[jayriddle]

Re: Smog for Gen I -- Can\'t get RPM Reading?

I'm not sure where they were trying to get the signal from, but I'd expect from the wires. They probably tried multiple -- each shop said they tried hard to find the signal, but couldn't

I guess I'll take it to a dealer with a Viper tech and hope they have a better shot via the PCM.

 

[dansauto]

Re: Smog for Gen I -- Can\'t get RPM Reading?

if its the wires then this is a common problem (ask anyone that has been on a dyno) just try another wire.