Sponsored

2021 JLUR (manual, 3.6L ESS) Won't Start

OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
How did you confirm the switch was good? It pulls a signal to ground, so did you check both voltage on one wire and impedance to ground on the other - while pressing in clutch?

Note from diagram signal to this switch goes through radio freq module before ECU. Thus, if switch is confirmed good, then I think you need to find that RF module and probe both sides of it and/or where signal enters the ECU. Quick and dirty - disconnect related connectors and re-seat. Most electrical system issues are at the connectors.
Are we talking about the same clutch interlock switch as in the pics? If we are, then I did the following assuming I am testing a basic on/off switch:
  1. I disconnected the switch connector
  2. I checked the two pins on the mail connector and the circuit was open. I then depressed the clutch and the circuit became closed. I released the clutch and the circuit became open again.
  3. I depressed the clutch and then push start button twice that got me into Run mode. I pushed it again and the panel turned off (same as what happens with the clutch released). Then, I reconnected the plug and the Jeep would no longer turn off when I push Start button subsequently.
Please let me know if I missed anything.

Screen Shot 2021-02-21 at 5.14.58 PM.png


Screen Shot 2021-02-21 at 5.26.57 PM.gif
Sponsored

 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
You need to test it in-situ. Use a needle to get through insulation, verify voltage on pin 2 and that voltage starts high and indeed gets pulled near ground when switched. Note voltage levels. For completeness, measure resistance to ground on both pins with no power - actuate clutch.
 
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
This is what I’ve measured when the start button is in “Run” position:

P2 - clutch interlock signal on connector pin 2
P3 - sensor ground on connector pin 3
Grnd - vehicle body ground

With clutch released
P2->P3 = 4.77V / OL (Open Line)
P2->Grnd = 0V / OL
P3->Grnd = 0V / 180 kOhm

With clutch depressed
P2->P3 = 0.02V / 8 ohm
P2->Grnd = 4.78V / 175 kOhm
P3->Grnd = 0V / 175 kOhm


EDIT: Please disregard these. They were measured against wrong ground. The correct measurements are in the post #101 down below.
 
Last edited:

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
I’m not clear on what you are measuring - you’ve pierced the insulation and all is connected as it came from factory?

Note pin 3 should be 0 ohms to ground per wiring diagram - you’re reporting 180k? What are you probing to call ground? Double check all that. Pin 3 not grounded would be a problem. Check all connections on that wire.
 
Last edited:
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
I’m not clear on what you are measuring - you’ve pierced the insulation and all is connected as it came from factory?
Yes. And the start button is in Run position. I’ve attached the picture showing the needles.


Note pin 3 should be 0 ohms to ground per wiring diagram - you’re reporting 180k? What are you probing to call ground? Double check all that. Pin 3 not grounded would be a problem. Check all connections on that wire.
I think you are right. Looks like I’ve picked false ground. I was measuring against a piece of nearby metal bracket that looked like connected to the body frame. This time I measured against main battery (-) terminal and the resistance between Pin 3 and ground was indeed 0 Ohm.

I’ll redo all measurements tomorrow when I have someone to depress the clutch and post them again. Thank you for catching this. 👍🏻

277095A9-877B-41EB-B9EA-01ABA562CC2B.jpeg
 

Sponsored

jellis4148

Well-Known Member
First Name
John
Joined
Nov 3, 2018
Threads
81
Messages
1,073
Reaction score
1,405
Location
Missouri
Vehicle(s)
2019 Jeep Wrangler JLU Rubicon
So, not to be a smart ass, even though I'll sound like one. I've followed this post, and forgive me if I've missed this, but you've had this problem for a little while, the Jeep is under warranty, and you've have tested, unplugged, plugged, and done all kinds of things. Why not just take it to the dealer? I will bet they can have it diagnosed in about a few hours. Just like the Challenger I sold that did the same thing. They figured out it was the PCM in about 45 minutes. Ordered the part, and it was good to go. I know you or someone will say dealers are bad or something similar. We have a very good service department. Granted they don't fix every single car the first time, but even doctors misdiagnose sometimes. So for all the time, and days you've spent doing this. Why not take to dealer? That's what a warranty is for. If you don't care about warranty, you could've saved money and bought a used 18 and saved quite a bit.
 
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
So, not to be a smart ass, even though I'll sound like one. I've followed this post, and forgive me if I've missed this, but you've had this problem for a little while, the Jeep is under warranty, and you've have tested, unplugged, plugged, and done all kinds of things. Why not just take it to the dealer? I will bet they can have it diagnosed in about a few hours. Just like the Challenger I sold that did the same thing. They figured out it was the PCM in about 45 minutes. Ordered the part, and it was good to go. I know you or someone will say dealers are bad or something similar. We have a very good service department. Granted they don't fix every single car the first time, but even doctors misdiagnose sometimes. So for all the time, and days you've spent doing this. Why not take to dealer? That's what a warranty is for. If you don't care about warranty, you could've saved money and bought a used 18 and saved quite a bit.
Thank you for your input and a valid point. Like I've mentioned in one of my earlier posts, I already have a dealership appointment this Thursday (4 days away). In the meantime, I was trying to see if this was a simple fix that I could do myself (like a loose connection, a faulty sensor, etc.). This helps me to understand and to be better prepared to troubleshoot if something happens on a trail when I'm miles away.

At this point it appears it is not an easy fix and I am set on heading to the dealership on Thursday. Maybe the dealerships in Missouri are different, but here in SoCal I yet to find one that would give me a positive experience. Also, putting the doors and the roof back on, undoing mods, then leaving the Jeep in the general dealership parking lot for days is an extra burden that I'd rather not have as long as the fix is trivial.

I also hope that my research, pics, and recommendations expressed by other Jeepers in this thread will help our growing community in the long run should they experience a similar problem.
 

jellis4148

Well-Known Member
First Name
John
Joined
Nov 3, 2018
Threads
81
Messages
1,073
Reaction score
1,405
Location
Missouri
Vehicle(s)
2019 Jeep Wrangler JLU Rubicon
Thank you for your input and a valid point. Like I've mentioned in one of my earlier posts, I already have a dealership appointment this Thursday (4 days away). In the meantime, I was trying to see if this was a simple fix that I could do myself (like a loose connection, a faulty sensor, etc.). This helps me to understand and to be better prepared to troubleshoot if something happens on a trail when I'm miles away.

At this point it appears it is not an easy fix and I am set on heading to the dealership on Thursday. Maybe the dealerships in Missouri are different, but here in SoCal I yet to find one that would give me a positive experience. Also, putting the doors and the roof back on, undoing mods, then leaving the Jeep in the general dealership parking lot for days is an extra burden that I'd rather not have as long as the fix is trivial.

I also hope that my research, pics, and recommendations expressed by other Jeepers in this thread will help our growing community in the long run should they experience a similar problem.
Well, I hope they do fix it, and it's a good experience. Working at a dealership for over 20 years selling cars. It always bothers me when someone says a dealership sucks or doesn't have customer service. I see both sides quit often, and a lot of times it's both sides fault. Not talking about you personally. Some people have too high of expectations, and think we can wave a magic wand and poof the car is all better. I promise that here we don't want you to come back mad. When I sell a car. If a customer calls me with a problem. I immediately get it into service, and if it's only a $500 or less to fix. The dealership will pay for it without question. That's if they car was recently purchased. Anything over that, we will still more than likely fix as long it wasn't abuse. Hope they fix it for you. Good luck.
 
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
Well, I hope they do fix it, and it's a good experience. Working at a dealership for over 20 years selling cars. It always bothers me when someone says a dealership sucks or doesn't have customer service. I see both sides quit often, and a lot of times it's both sides fault. Not talking about you personally. Some people have too high of expectations, and think we can wave a magic wand and poof the car is all better. I promise that here we don't want you to come back mad. When I sell a car. If a customer calls me with a problem. I immediately get it into service, and if it's only a $500 or less to fix. The dealership will pay for it without question. That's if they car was recently purchased. Anything over that, we will still more than likely fix as long it wasn't abuse. Hope they fix it for you. Good luck.
Sounds like you are an ethical and an honest man. I wish we were neighbors. Let you guys know how it all goes this time and what the fix is.
 

Sponsored

OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
These are the new measurements (thank you @NBB) with the start button in “Run” position:

P2 - clutch interlock signal on connector pin 2
P3 - sensor ground on connector pin 3
Grnd - main battery (-) terminal

With clutch released
P2->P3 = 4.8V / OL
P2->Grnd = 4.7V / OL
P3->Grnd = 0V / 13.6 Ohm

With clutch depressed
P2->P3 = 0V / 7.2 Ohm
P2->Grnd = 0V / 22 Ohm
P3->Grnd = 0V / 14.8 Ohm
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
Your first set of measurements was certainly interesting, like maybe you were on to something. However, this set is different and indicates the switch is working per schematic. The 5v signal appears to be getting pulled to ground. ~14 ohms for a length of battery cable + your probe wires + sensor wire + some engine metal seems reasonable enough to say this isn't an open ground.

As suggested - for a vehicle under warranty - I'd likely stop here.

There could still be a problem with this signal, but it would be on the other side of the RF module. Even if you probed and found an issue there, you wouldn't be able to fix it. The RF module likely needs programming via a secure connection to TechAuthority with WiTech.

The clutch position sensor also seems buried as you found. I would want to see codes before digging for it - or before doing anything more at this point.

Let us know what codes your new scan tools find.
 
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
My OBD2 MX+ sensor has just arrived. I've paired it with the JScan app and this is what it's reporting - P0808 (clutch position sensor "a" circuit high).

Common repairs for this code from https://www.obd-codes.com/p0808:

  1. Cleaning corrosion from connectors
  2. Repairing or replacing faulty wiring
  3. Replacing blown fuse or fuse-able link (if applicable)
  4. Repairing or replacing faulty ground straps
  5. Flashing or replacing the PCM or TCM (multiple sources said this was most unlikely and rare)

I am not sure yet which of the two this applies to - the Clutch starter interlock switch (68029261AA)
and the Clutch pedal position sensor (68333561AB). Perhaps the latter?

Jeep Wrangler JL 2021 JLUR (manual, 3.6L ESS) Won't Start IMG_2125.PNG
 
Last edited:

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
Computer is likely flagging an "implausible" reading between the switch you just tested and the position sensor - ie, the potentiometer you went digging for but didn't get to. You press in clutch and the sensor should read low(er), because the computer sees the switch you just tested changed - but the sensor isn't changing - it is reportedly staying high. This "implausible" difference throws a fault.

This means the 5v is likely getting to the sensor (pin3 at the sensor), and is also feeding back a ~5v signal to the computer, which sees it high (pin 4 at sensor). A potentiometer is just a resistor - not something that fails easily - and if it did fail it would likely report open or high resistance - or low voltage.

I would check first for a mechanical connection problem where the clutch pedal (or whatever) is physically not moving the sensor. This seems like the highest probability of being the problem. I would then inspect the sensor for physical damage and manually actuate it to see if it changes your problem.

I would then suspect connectors - of which the wiring diagram indicates a total of 4 involved in that signal. However, 2 of the 3 pins are supposedly working and connected back to the ECU, so digging deep for all of them seems risky that you'd be wasting your time. I'd therefore find the most accessible part of that circuit and break out those needles again and start probing wires as the clutch is depressed - hunt down connectors if this shows a problem.

How interested are you? This is a straight forward repair for the dealer, unless they find evidence you've messed with one of those connectors. Even if they charged you full price outside of warranty, it seems like at most a $300 repair - for what should be a < $100 repair. I can't help you with locations, maybe others can.

EDIT - Or....since the code is "pending", and since you've been in there messing around - it all could just mean you had one of the connectors disconnected, or it is from when you did that short thing as posted above - ie, shorted the switch closed without pressing clutch. FIRST - clear codes and see if code comes back.
 
Last edited:
OP
OP
demisx

demisx

Well-Known Member
First Name
Dee
Joined
Jul 9, 2020
Threads
6
Messages
264
Reaction score
203
Location
Desert Hot Springs, CA
Vehicle(s)
Wrangler JLU Rubicon
Clubs
 
Computer is likely flagging an "implausible" reading between the switch you just tested and the position sensor - ie, the potentiometer you went digging for but didn't get to. You press in clutch and the sensor should read low(er), because the computer sees the switch you just tested changed - but the sensor isn't changing - it is reportedly staying high. This "implausible" difference throws a fault.

This means the 5v is likely getting to the sensor (pin3 at the sensor), and is also feeding back a ~5v signal to the computer, which sees it high (pin 4 at sensor). A potentiometer is just a resistor - not something that fails easily - and if it did fail it would likely report open or high resistance - or low voltage.

I would check first for a mechanical connection problem where the clutch pedal (or whatever) is physically not moving the sensor. This seems like the highest probability of being the problem. I would then inspect the sensor for physical damage and manually actuate it to see if it changes your problem.

I would then suspect connectors - of which the wiring diagram indicates a total of 4 involved in that signal. However, 2 of the 3 pins are supposedly working and connected back to the ECU, so digging deep for all of them seems risky that you'd be wasting your time. I'd therefore find the most accessible part of that circuit and break out those needles again and start probing wires as the clutch is depressed - hunt down connectors if this shows a problem.

How interested are you? This is a straight forward repair for the dealer, unless they find evidence you've messed with one of those connectors. Even if they charged you full price outside of warranty, it seems like at most a $300 repair - for what should be a < $100 repair. I can't help you with locations, maybe others can.

EDIT - Or....since the code is "pending", and since you've been in there messing around - it all could just mean you had one of the connectors disconnected, or it is from when you did that short thing as posted above - ie, shorted the switch closed without pressing clutch. FIRST - clear codes and see if code comes back.
Thank you very much for your detail reply. I will re-read it again tomorrow morning and try to digest it. I am more in a learning mode right now and will not be doing anything crazy. I may just check physical connections like you said and study the wiring diagrams for my own education (that warranty will run out at some point), but I will not be messing with anything - it's going to the dealer on Thursday.

To address your last point, I did clear codes multiple times and then re-read them. When I first connected I saw a bunch of them, now I'm just consistently getting this P0808 one.
Sponsored

 
 



Top