My 98 xj did not pass emissions. Code P0138 - rear o2 sensor, code P0707 - for the transmission sensor. It also failed the engine light test, meaning it never came on, never was on, still isn't, doesn't come on when I turn on the key. I recently bought the jeep so I'm figuring the dude rigged the light. How do I get to it? I didn't think there was a fuse but maybe? Please help, thanks

 

Simply replace the rear O2 sensor. The PO probably removed the light in the dash. Will need to replace the bulb. Im not sure on the P0707 error.. Hope someone else chimes in on that one..

Pick up an ELM327 Bluetooth OBD II reader from eBay or Amazon. It works with a smartphone to read codes, and reset the ECU once repairs have been completed. Best $20 I spent so far.

 

P0707 doesn't exist in the Jeep OBDII codes listing. It is some generic code. If you Google it, it will show up as a Transmission Range Switch "A" circuit low voltage. I have no idea what "A" circuit is. A good scanner can be programed to show Chrysler codes.


Basically there is a fault in the TRS (commonly referred to as the "NSS").


The NSS can be removed, cleaned, or be replaced with a rebuilt unit. You can search the web or Jeep forums for procedures.


There is a connector near the transmission dipstick that carries the TRS/NSS signal wires. It can be uncouples and checked for corrosion in the pins and pin cavities.


Resistance of the TRS/NSS contacts can be checked from these pin cavities. And voltage readings from the TRS/NSS can be taken from the Transmission Control Module as well.


If you are interested in testing let us know and guidance can be provided.


TRS/NSS connector:



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Contacts inside of the TRS/NSS. #3 is a 12 Volt bus bar that, when a gear is selected, transfers 12 Volts to the other individual contacts (except Park and Neutral, #7 & #8):



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Connector pin out/continuity chart:



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