I have a 2001 Dodge RAM 1500 5.9 4x4 A/T California Emissions with 230,000 miles on it. I am having issues with getting DTC codes P0132 for the upstream oxygen sensor and P0141 and P0138 for the downstream oxygen sensor. Both oxygen sensors have been replaced and the DTC codes keep coming back even after PCM was reset. Here is a little background on all of this. This all started when the PCM began to fail intermittently and the vehicle began to stall every time the "NO BUS" error occurred and I started to get the "NO BUS" on the odometer display. I troubleshot it myself by using a blow dryer. I took and had the PCM repaired at a PCM service center. Got PCM back after a month, installed the repaired PCM and the repaired PCM failed within 30 minutes. Took PCM back and PCM service center was unable to fix the PCM, so after another month of waiting they gave me a replacement PCM. I installed the replacement PCM and all of a sudden I started to get all of these DTC codes and vehicle RPMS started fluctuating at idle as if the vehicle was going to stall and sometimes it stalled at idle and sometimes the RPMS recovered and while driving the vehicle seemed like it was seriously lacking power for a V8. So, I started doing research and found that the Plenum may be an issue and I found a lot of oil in the intake, so I rebuilt the intake manifold with the Hughes Engines rebuild kit. I replaced any vacuum hoses under the hood that looked old and replaced the PCV, vacuum check valve on the brake booster, TPS, IAC, ECT, MPS, spark plugs, spark plug wires, cap, rotor. I did notice some corrosion on the ground wire that runs from the cab to the engine block on the driver's side/bank 1 side, but I have not had a chance to fix that ground yet, but I will in the next couple of days. I got laid off of work after 18 years as a Systems Technician and can't afford to take it to a mechanic and pretty soon I won't be able to afford to throw parts at it, but this is my only transportation for now.

What kind of DVOM readings can I expect to see on the Bank 1/oxygen sensor 1 PCM circuit at the 4 pin round connector with the oxygen sensor disconnected and the key on and ignition off? I suspect that I still may have an issue with the replacement PCM.

Any other suggestions are greatly appreciated!!!

 

Heater circuit should have 12 volts, two wires are ground, one is sensor feed, the other is return to pcm. Feed should be 1 volt, or 5, can't recall which.....

Keep in mind, the heater circuit is powered thru the ASD relay. So, only have power for a about three seconds after turning the key on, if the engine isn't running.

 

With the O2 sensor disconnected, I measured all 4 pins of the Bank 1/1 O2 sensor circuit and did not have 12V on any of the pins, but I did have 5V on one of the pins. I also measured Bank 2/1 and had the same results.

I found a O2 sensor diagram online that showed exactly what you described should happen through the ASD relay even though the wire colors on the diagram did not match the wiring on my harness at the O2 sensor circuits.

In the PDC, I have a 15A fuse labeled "O2" and it has 12V on it at all times, even with the key off and even when I pull the ASD relay. In the PDC I also have two other relays that are labeled "O2 Heater Front" and "O2 Heater Rear" Not sure what all this means at this point.

If anyone has any diagrams or experience, please help. I am more than willing and able to troubleshoot this with your help. My Smog Check is due by the end of this month.

PLEASE HELP!!!

 

Bugger.

I just wrote out a bunch of stuff that doesn't apply to Cali spec.

Let me revise.

Ok forget that. Send me a message and I'll email you the schematic pdf.

 

Please email me the schematic pdf. Do you need my direct email address or will you be emailing it through the forum system? I am new and not sure how all this works, but I am slowly learning. I am a computer guy, but I don't have the experience in how to navigate this forum properly and efficiently.

 

Need a direct email. I tried uploading as an attachment but apparently we're limited to like 50k worth of attachments or something ridiculous.

 

PM him your Email address, don't post it on the open forums. Unless, you LIKE getting spammed to death.

 

I forgot to mention that I did swap out the ASD relay with another one that is the same to make sure the relay was not bad, but still no 12V on the O2 sensor circuit off of the harness.

Any other suggestions or things I can troubleshoot until I get an actual service manual? Do you know how I can find a service manual on this forum for this specific vehicle or at least a diagram that shows the flow for the O2 sensors?

 

You can download the service manual for your truck from this thread. Wiring diagrams are in section 8W.

 

https://dodgeforum.com/forum/2nd-gen...-problems.html