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2002 XLE ECM pin out Help Please

3140 Views 9 Replies 3 Participants Last post by  pjksr02
I have checked about all the info and pdf's posted here but can not find an actual pin out for the ECM ?? What I am hoping to find are the actual wires that run from the post catalytic converter O2 sensor to the ECM .Yes I am having trouble with the check engine light and the P0420 code.I read about a mod on another site for another vehicle that I think may work.I have years of experience in electronics and engineering and if this works out I will post it up as well.Thanks in advance for any and all help . Matt ;D
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Thank you , I hope I can figure it out from there .Was hoping to get an actual "pin out" as compared to a schematic .I may just do the mod outside by the O2 sensor but was hoping to do it in the cabin by the ecm.
Building a little low frequency oscillator to simulate a sensor output, by chance?
So far, I've been fine with having replaced my two A/F sensors, and the O2 sensor. I recently purchased an updated ECU on EBay, and am going to install it after my upcoming OBD inspection.

Consider replacing those sensors...
going to try just a rectifier diode off the + line of the O2 sensor going into the ecm ......first .:)
You might be able to get away with that on a 2002. The more sophisticated systems watch for a duty cycle and rep rate that mimics but trails the front sensor's output.
Open to suggestions ,will probably try the mod tomorrow evening :)
Step one is to understand what your current O2 sensor is outputting. If your cat is really bad, then the rear could be totally in lockstep with the front and swinging wildly. If the sensor is bad, it could be insensitive to either rich or lean. Trying to doctor the output without knowing your starting point will likely not work. Never mind that it's also not the right thing to be doing!
More considerations:

All three sensors are likely degraded at this point. Commonly, an A/F sensor will be the first to throw a code, on our vans; some report P0420 first, though.

The P0420 scenario combines degraded sensors with a catalytic converter that is no longer operating at brand-new efficiency, and an ECU with super-strict logic. There are many variables.

Amazon currently has our A/F sensors for about $90 each, and the O2 sensor for about $45.

Also, if you have Techstream, you can compare ECU-calculated P0420 test values with limits. This might be useful if you change parts.
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