sorry that was too harsh! Crabby cabin fever!!

 

ok I put my RCM back in. I put some solder on the two connections on the RCM board that always give us crossfire owners issues, Figured might as well do it while its out.I will update on connector status asap. Its snowing outside now, and I am fixing this car old school way, outside in the muddy driveway under snow fall in the dark. Determined to fix this

 

Easy there ! just trying to help , Had same thing going on 2 ,3 yrs ago found that i had air leak around TB clean up the boots around TB , and no more light ,

 

tunaglove,
does the car need to be running when i check for voltage or just turn the key forward without it running. Im headed out to test the voltage. will update status in 15min

 

ok so i tested the red wire with the green stripe, the best i could get was 10.45 volts out of that plug. It could of been the way i was holding my multimeter because im on back in mud, deep in snow but i did pull the highest of 10.45 volts on that line. what would be the next step, any other recommendations

 

i checked the harness, it is not up against any of the manifolds, it still has the heat shield on the wires

 

Sounds like to me it's time for you to talk to Rudy can answer anything I maybe able to fix your problem

 

ok so i pulled sensor apart and cleaned it, checked the harness, cleaned the connectors in the rcm. replaced wires, turned car on and off twice and cel came back on again!!!

 

Well Im just about out of ideas for you.

Seems strange to get a heater error due to an air leak but I guess I would turn towards looking for that.

10.45 volts seems a little low but you have covered the basics. Since you are already under there compare the pin 1 of the other secondary O2 sensor to see if it is 10.45 also. I know you are laying in the mud and cold and you qualify for the tough guy award, I know that is NO FUN! You could try ohming out the other heater wire that goes back to the ECU to make sure that is connected. That is in the schematic I noted earlier.


That's about all I can think of for now sorry.

 

Im gonna keep trying my 10 day inspection is up so need to keep working at this

 

Have you looked at the repair manual and looked for the possible causes of the fault code?
If not go here. Repair Manual, 9 - 128 ENGINE - ELECTRICAL DIAGNOSTICS
They write these manuals for a reason.

 

I'd like to suggest measuring the heater voltage under load. Keep the sensor plugged in and measure the voltage across the two heater pins. If you have a high resistance in the wiring, having a load on the circuit will drop more voltage across the bad point and your meter reading (measured voltage) will be lower. If this is true, the next step that I'd do is measure pin 1 to a good ground. If the voltage is close to battery voltage then you know that the other wire or connections are suspect.
For reference, do this procedure to a known good sensor and you will know what you are looking for.
What is the measured voltage at the fuse, and across the battery? I haven't looked at the wiring diagram yet, but this will give a good start on diagnosing the wiring.

 

Pretty much the steps I outlined for him.
Good luck, check that wire going back to the ecu.

 

Does anyone bother reading posts prior to replying? He's past that part already.

 

what voltage should be at the wiring harness in order to get this sensor heater to work? I measured 10.45volts. My battery is new and is measuring 12.5v Would cutting out the end connections and directly wiring the sensor to the harness work possibly? Im thinking if there is something bad in the connection I can eliminate it. A weak point for voltage drop is always at connections. And if i shorten the wire it would give me less resistance in the wire and able to transfer more voltage to the sensor. Sound possible to work?? How do i how that the heater is working in the sensor?

 

Yes, I read ALL of the posts, re-read my post, your previous suggestion was to measure an open circuit voltage, this is NOT the best way to check for voltage to a circuit. if there is high resistance in a connector or a fuse that has high resistance (yes, I've seen them) or any other high resistance in the circuit the open circuit voltage may be close to the battery voltage, but under load the voltage will drop, possibly to almost 0 volts.

Ideally, this test would be done with a load to ground and then measure the voltage across the load. This would verify the power side of the circuit. Unfortunately at this point we don't know what the output of the PCM is, it provides the ground side of the heater circuit and does this with a PWM. Since the sensor has been changed multiple times, I am assuming that the heater is okay (yes, possibly a bad assumption but I'm going with it for now.)
I just finished looking at the wiring diagram and all for sensors get their power from the same fuse, since only one sensor is failing it should be safe to assume that the power at the fuse is ok. The next step is to verify proper battery voltage to the sensor, after that its the wiring to the PCM and the PCM itself.

 

compare the voltage supplied to the other rear sensor. If its 10.45 check the wiring back to the ecu. If its more than 10.45 (closer to battery voltage, go through all the connectors going from the RCM to pin one (red with green stripe).

 

if you are doubting the sensor's heater measure pin 1 to pin 2 (ohms unplugged) and compare to the other rear sensor heater.

 

I agree that putting a load on the circuit would be a better test. However, the pcm does not supply the ground to the heater until the engine is running. He's already stated he is in the driveway in the mud, so let's save that test for last.

 

I've seen several people get off track by not loading a circuit when taking measurements, I'd rather do it right the first time, and make sure. And yes, I'd like to keep him out of the mud too, but it appears he has a deadline to meet!

He could use one of his old worn out sensors that has a good heater in it for the load, just cut off the heater minus wire at the connector and ground it to a good ground, turn on the key and measure the voltage at the connector. Just remember that the sensor might start to heat up. If he is still close to that 10.45 volts then we know it isn't that side of the circuit.