Service Engine Light

So as of tonight I'm the new owner of an Electra. Previous projects were Pontiac Transports and Luminas. This one is loaded with gadgets. Hopefully this will be the last project in a long while. lol

The service engine light stays on. Any suggestions where to begin looking? Engine runs fine.

Thanks

Um yeah, check the codes? Jump a and b teminals on the aldl connector count the flashes or scan it.

Was hoping to do that. Late last night I went looking for the connector. Where did they hide the darn thing? Usually it's near the column.

Should be to the r/s of the column, more under the dash a little hard to see.

It is. Found it about center. I expected left side. Code 14. Signal level low or shorted.

Digging further. I believe the sensor is located near the plenum and not far from the upper rad hose.

Thanks

Checked the sensor resistance cold and later after warming the engine. 5000 ohms cold and about 350 ohms hot. I'd guess the sensor is working right. Voltage at the sensor, engine warm, was about 2.33 volts. I can't recall what it was when cold. Will check further in the morning.

Further to my problem. I acquired another sensor and tested both in heated water. They match fairly closely as the temp rises and compare favorably to the chart I was given. The problem is in the ECM. I can get a code 15 if I open circuit the sensor but any other time after clearing the codes I get a code 14. I even attached a potentiometer in place of the sensor. With settings as high as 400 K it will still trigger a code 14.

A full scan would show what the pcm sees from the sensor, eliminate some guess work here, also check the resistance of the sensor wires from the sensor to the pcm.

What do you mean by full scan?

I changed the PCM today (keeping the orig PROM). No luck. The light is still there. Engine runs fine with either ECM.