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What is o2 sensor output from MS?

Posted: Mon Oct 11, 2010 4:55 pm
by usagoal
Ford windsor 351, pertronix ignition off negative coil, MS-II V3 2.86 code. Relay board.

Our engine runs but I'm not getting a reading on the o2 sensor (narrowband). It "used to" show a signal on MT, but no more. Shouldn't there be a 5v output from the MS and through the relay board? I checked with a meter while the engine was running and didn't get a reading. I checked for continuity throughout the relay board and MS (even checked some of the components in the circuit which seem to be ok). It works on the Stim, but not on the engine. Any ideas where to go from here? I followed the schematics back to the o2 circuit. It looks like the processor puts out the necessary 5 volts in order for the circuit to operate? The o2 sensor I'm using had worked on a previous project, but before I spend another $20 on a new sensor, I would like to figure out what kind of output I should expect and test for it. Thanks.

Re: What is o2 sensor output from MS?

Posted: Tue Oct 12, 2010 6:16 am
by Matt Cramer
The O2 circuit is an input, not an output. If you're not getting any volts on it, it's likely an issue with the sensor.

Re: What is o2 sensor output from MS?

Posted: Tue Oct 12, 2010 8:09 am
by usagoal
Of course! (as I slap myself in the head) I was mistaken and thought it had worked off of resistance through the sensor. oops. Thanks for clarifying matt.