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Discussion Starter · #1 ·
2005 jeep rubicon 102k 35 inch wheels stock gears 4.1

Live in central CA where its about 105 outside now.

I have had no codes for about 6 moons. But i recently began getting the p0700 and p0720 again. I replaced the OSS in January about 6 months ago. I just replaced the ISS sensor as well as read that some do this at the same time and I didnt do this previously still codes. I have the new wranglerfix pcm.

I seem to be able to drive ok for about 15 miles , perfect shifts while the tranny temp is under 190 ( I have a tranny temp gauge) then i restart jeep and get a hard shift get the codes , then go into limp mode and tranny doesnt want to shift past 2nd or 3rd then.

Only thing recently done was I went through a water hole that was a little deeper than I thought. about up to rocker bars for about 20 seconds then I was out.

I have ordered a new OSS on the off chance I broke it while wheeling which I havent gotten too crazy. Ill have that in within a few days.

Anyone experience with this. If the new OSS doesnt resolve what then ? Tranny shop?

Previous thread. p0031 p0037 p0051 and p0057 05 rubicon 100k miles 42rle...

Thanks in advance,
 

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Discussion Starter · #3 ·
oss output speed sensor rear of tranny
Iss input speed sensor middle of tranny
I believe These give feed back to the tcm in the pcm about when to shift. They have Magnets in them and you can hook up a voltmeter and see that they change resistance ohms when you pass a magnet by them.
42rle tranny
102k on rig and the tranny
also recently changed tranny fluid last change at 80k
 

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Discussion Starter · #4 ·
https://wranglertjforum.com/attachments/2006-tj-powertrain-pdf.14050/ has a trouble code resolution process for p0720 if the new oss doesn't resolve will run through this. Reading these sensors can break when wheeling. I didnt think I hit anything too hard but who knows how sensitive these are. Im hoping that if the solenoid was going out i would get a specific solenoid code.
 

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Thank you for asking. Confirmed no non Mopar electrical thing ever.
When you get your new sensors, I would put some dielectric grease in the connectors. If you have a Harley store nearby, they used to sell it. Harley used in their connectors to keep water out to prevent weird things happening. Harley put it mostly on those connectors that were important. The computer connectors and such. Just an idea for when you go underwater, as an extra measure.
 

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The OSS is a two wire with a feed from the pcm and shared ground to pcm with the input sensor. If you don't find contamination in the connector then you need to properly check the wires. Wiring needs to have a resistance test with a ohm meter and also load tested. Easiest way to do this is with a old school test light.
If you actually had a internal transmission problem I would think that you would be getting a bunch of gear ratio error codes also.
It would be nice to have a scanner so you could see what was going on.
 

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Discussion Starter · #11 ·
The OSS is a two wire with a feed from the pcm and shared ground to pcm with the input sensor. If you don't find contamination in the connector then you need to properly check the wires. Wiring needs to have a resistance test with a ohm meter and also load tested. Easiest way to do this is with a old school test light.
If you actually had a internal transmission problem I would think that you would be getting a bunch of gear ratio error codes also.
It would be nice to have a scanner so you could see what was going on.
Thank you Rlenglish! This is good news. Are you in Canada? I lived in Victoria for a while.

I'll Take any suggestion on a scanner tool with the necessary functionality. I only have a fixd obd right now and while it is somewhat useful for the cost it lacks functionality I think you are referring to what would I be looking for on the OBD tool.

I found this https://wranglertjforum.com/attachments/2006-tj-powertrain-pdf.14050/ I have a 2005 I hope its close enough. Search p0720 code to troubleshoot but I dont have a transmission simulator.

I have this light sensor says it draws 21 ma at 12 volts is this enough to load test the wiring ?

I believe the load testing with a light you are referring to is this. https://www.alldata.com/sites/default/files/file-attachments/electrical_circuit_testing.pdf please let me know if not correct Ill try and disconnect the harness and the oss sensor and do this load test and resistance test now.
 

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Discussion Starter · #13 ·
Disconnected the PCM Wiring Harness and the OSS Sensor Connector.
Infinite resistance between the 2 wires as expected indicating no short to ground there.

Font Parallel Screenshot Number Document


Resistance was in the 1.0 ohms ish vicinity had a paper clip into the sensor connector which I have used to backprobe in the past. I think this value is fine since this manual says it should be below 5.0 ohms.


Font Rectangle Parallel Screenshot Number


I dont understand how to test the short to voltage as its indicating in step 7 although I have pulled the transmission control relay from the PDC

Font Parallel Rectangle Number Screenshot


Or how to load test it really with the light ?
 

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Pcm connector disconnected. output sensor disconnected. ohm meter each circuit individually to a good ground, should be open circuit as both connectors are disconnected. Ohm check wires to each other at oss and at pcm, should be open.
The voltage check they are referring to is by jumping the tcm relay so it stays on and looking for voltage which would be a short to battery on either wire.
Load testing any wiring is a good idea. If you had a severed wire that had just one strand of wire left, then it would ohm check good but not be able to carry load. With pcm and oss disconnected jump one end of the wire to ground, then at the other end hook your test light to power and the selected wire. Test light should be bright. You are just making a wiring circuit from power to ground without any other components. Your test light will be okay, it doesn't draw much but as long as it is a filament style bulb you are good. If ever in doubt you could use a taillight bulb of even headlight.
Victoria is nice other than dealing with the Ferry. Lately they have been cancelling sailings due to staff shortages leading to long wait times. I live in a smaller town about half way through the southern part of the province.
 

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Discussion Starter · #15 ·
rlenglish much appreciated your comments are very helpful, used to live near the johnson street bridge iirc.

Did that test and the results were the light came on bright for the connector I was trying the output sensor signal left side connector output speed sensor signal pin 32 lit up as expected measured with multimeter over 12 volts. right side pin 34 lit up. Also measured iss sensor left side pin 33 lit up 12 volts, right side pin 34 lit up.

Also did this test
10 minutes in
for short to voltage and no light, replace the o2 sensor with oss sensor in this case I was testing on pin 32 on the pcm connector 4.

Gesture Font Parallel Whiteboard Presentation


I'll have the mopar replacement oss shortly, will update then, but after these wiring tests makes me feel pretty good that I must have broke the oss somehow.

Thanks to everyone who added input.
 

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Have you checked this:

Come to find out that the plastic wire loom going from the PCM/TCM was deteriorated and the wires had rubbed on a sharp edge of the bell housing causing a short.

 

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Discussion Starter · #19 ·
Have you checked this:

Come to find out that the plastic wire loom going from the PCM/TCM was deteriorated and the wires had rubbed on a sharp edge of the bell housing causing a short.

Will do so how do I check this ? On top of the transmission ? I'm in super hot central ca. I tried to replace some of the plastic that was falling apart like paper due to heating. Perhaps in another spot.
 

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Trying to go off of memory here so bare with me. Passenger side of engine compartment for sure but can't remember what part of the harness it was now.

Basically follow the harness from the transmission plug off of the pcm on the drivers side of the engine block. Where the block and transmission are mated is where these harnesses tend to rub.

If you already have crumbling plastic wire loom, I would unplug all that you can and lay it out over the fender if possible and check every wire for bare spots. Get some new split loom before you put it back together. If this isn't the problem now, it could be later if you don't address it.
 
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