Greetings all those wiser and smarter than me!!
I have a 1992 Pathfinder. Its sat a long time so I'm now trying to get it running right.
Biggest current problem is that it will not advance from open to closed loop. I have a 1995 Pathfinder also and that goes into closed loop as expected.
The O2 sensor and its heater seem ok, although some of the resistance and voltage readings are different from those on my 1995 Pathfinder. I just received a new O2 sensor and will check the readings on the new one and compare to the others before I install it.
The CTS seems ok.

These older vehicles do not have OBD ports ;-(

Any great ideas most welcome

Thanks

John

I've seen some cars that wouldn't go into closed loop until the O2 output reached a certain level. Disconnected, what output voltage are you seeing? Coolant temp is another, does it run about where it should? I've seen stats get tired with age and cars run really cool with old stats.

Hi Mike,

Thanks. The output voltage from the O2 sensor with the heater jumped (so its heating up) is about 1.34 V - which is above the theoretical max output of 1.0V The coolant temp seems ok. I'm going to check the O2 sensor harness per the service manual and replace the sensor. The new sensor when heated up but not installed puts out 0.1 V which is in line with the good sensor in my 95 Pathfinder. Also Mode 1 of the "OBD" is specifically called an "02 sensor mode" and it doesn't flash at all (indicating its staying in open loop). The manual says to check the harness for continuity to the ECM, check for correct heater voltage, and if the number of flashes are less than spec, to replace the O2 sensor.

john

1.34V??? That's crazy high. I've measured a couple of dozen O2 sensors over the years and never seen 1.0V. .9X yes, but 1V, no. I've got to think there's a wiring issue.

Hi Mike,

Thanks. Yes I could not find anything anywhere regarding O2 output over 1.0V so thanks for confirming this. It may take me a while but once I get to the next step I'll post results. I appreciate your input of your experience - extremely helpful.
john

Greetings experts ;-)

I have the 1995 Pathfinder FSM. Following the checking procedure for the O2 sensor connections between the O2 sensor harness and the ECM it has me check continuity between the sensor harness and pins 106 and 19 on the ECM harness. Neither has continuity. To me it would be reasonable if maybe one didn't have continuity, but both seems unlikely without any evidence of tampered or burnt wiring.
So before I rewire for continuity I would like to check that for the 1992 Pathfinder the same pins as the 1995 (106 and 19) are involved.
Does anyone know where I can get a pin out diagram for the 1992 Pathfinder or a wiring diagram showing O2 sensor to ECM connections?

Thanks

John