Novak Conversions Jeep Wrangler TJ engine mounts

2005 Jeep TJ 42RLE Neutral Safety Switch

RgK051

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Dec 29, 2025
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Texas
I've looked everywhere to find a solution hopefully someone here can help. The check engine light came on, got P0850, checked to see if it would start in any gear and it does, i replaced the switch, checked if it would start in reverse and it did not, checked in drive and it did not start, put in park and it started and it worked for a couple hours, i was driving to get the not ready monitors done to pass inspection, on my way back home CEL came on, P0850 back again and now it starts in every gear again. Is there anything i can check, i just got a new wrangerfix PCM for the o2 sensors that kept coming on, and that seems to be working. Any info that anyone has would be much appreciated.
 
I've looked everywhere to find a solution hopefully someone here can help. The check engine light came on, got P0850, checked to see if it would start in any gear and it does, i replaced the switch, checked if it would start in reverse and it did not, checked in drive and it did not start, put in park and it started and it worked for a couple hours, i was driving to get the not ready monitors done to pass inspection, on my way back home CEL came on, P0850 back again and now it starts in every gear again. Is there anything i can check, i just got a new wrangerfix PCM for the o2 sensors that kept coming on, and that seems to be working. Any info that anyone has would be much appreciated.
Was the switch hard to install,I thought they were above the valve body?
 
Was the switch hard to install,I thought they were above the valve body?

It is on top of the valve body, hardest part was getting the shift solenoid connector unplugged. That is another reason I'm here, i don't want to do that over again if i don't need to.
 
It is on top of the valve body, hardest part was getting the shift solenoid connector unplugged. That is another reason I'm here, i don't want to do that over again if i don't need to.

That’s what I was thinking,my bil,s 2008 Rubi has this problem,he has been starting it in neutral,or just pushing it up past park to start it,sounds like a pain to change.
 
how would i OHM check it? i have the old one still but not sure where to check.

I'd defer to @hear for a definitive and informed answer...but googling came up with several answers and I'll bet there might be a procedure in the FSM available to download in the resources section.

-Mac
 
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It's not an ohm check, there are multiple switches and a truth table to tell the PCM where the shifter is.

Pull up the FSM under Resources for wiring diagrams, theory of operation.

Overcomplicated....

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Edited to add:
You can ohm check it, you'll just need to check all 4 wires.
 
I'd defer to @hear for a definitive and informed answer...but googling came up with several answers and I'll bet there might be a procedure in the FSM available to download in the resources section.

-Mac

Somebody needs to donate me an 06 Rubi so I can start helping with troubleshooting these 42RLEs.
 
Thanks for the input, I'm guessing i need to trace wires back to the PCM to see if there is a short or open wire? I'm not great at electrical stuff but i know enough to get in trouble. Does the switch plug go straight to the PCM? I have the FSM on the pinouts for the plug where i get confused is to where that leads to.
 
It is on top of the valve body, hardest part was getting the shift solenoid connector unplugged. That is another reason I'm here, i don't want to do that over again if i don't need to.

I just went through the same thing. That switch is hard to get to from underneath. It sounds like a lot, but I reverted to going in through the transmission top on top. Remove the front part of the center console, 4 bolts for the shifter, slide the shifter over and reach in. Takes maybe 5 minutes.
 
Thanks for the input, I'm guessing i need to trace wires back to the PCM to see if there is a short or open wire? I'm not great at electrical stuff but i know enough to get in trouble. Does the switch plug go straight to the PCM? I have the FSM on the pinouts for the plug where i get confused is to where that leads to.

Tracing the wiring diagrams isn't the easiest thing to do, since you have to jump several pages to follow the whole circuit. What I sometimes do is re-draw it on to a single page (with the FSM page references) so I can see the whole thing at once. But you probably don't have to do that. Find each wire on the NSS connector and see where each one terminates (most likely at the PCM) by just following the trail of breadcrumbs in the wiring diragram. Then you can check for continuity etc.


I'll try to teach you how to fish:
  1. 8W-02-1 has the component index. The transmission range sensor is in section 8W-31
  2. 8W-31-1 has the index. The range sensor is on pages 8W-31-6, 7, 8
  3. It's not crystal clear from those pages which one is the neutral safety, but you can see which cavities & which wires on the connetor go to PCM connector C4. For example the "PN" wire is 18ga Yellow w/Dark Blue trace that goes from cavity 10 on the range sensor to cavity 24 on PCM connector C4.
  4. You can find more info on the connectors themselves in section 8W-80.
  5. ???
  6. Profit
It requires a deeper understanding of the starter circuit to know how the NSS signal allows/prevents the starter relay from closing. It's described in section 8F-32, and you can work backward from the starter/relay wiring diagram to see how it all interacts.


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Novak Conversions Jeep Wrangler TJ engine mounts