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
 
Wondering if I should be looking at this next. If this is where the fault is coming from. The diagram calls it "Sensor Brake Pedal Travel". Is it the same as brake pedal position sensor?

Screen Shot 2021-03-05 at 10.53.18 AM.png
Sponsored

 

OldGuyNewJeep

Well-Known Member
First Name
Don
Joined
Sep 21, 2017
Threads
85
Messages
3,816
Reaction score
6,828
Location
CT
Vehicle(s)
2018 Wrangler JL, 2016 Yukon XL
Got a call yesterday from the dealership. They said there was a broken wire in the harness and they fixed it. I picked it up and, indeed, the Jeep started without any issues. Drove off of the parking lot and... the check engine light (CEL) came on.

Got home without any mechanical issues. Decided to see what exactly was done. Besides a couple ripped off harness clips (apparently, the service never heard of the molding remove pry tool), I see that they've cut off the yellow sensor signal wire in the main harness and ran a new black wire from another harness in the passenger well all the way to the PCM. I'm not sure if this is an accepted way to fix it, but I'd rather see a new harness installed instead what seems like a bandaid. And, of course, only visible portion of the new wire was put in a loom. The rest runs as-is.

I've cleared all engine DTC codes last night and the CEL went off. I drove it around this morning and again no mechanical issues. But, the CEL came on again after about 30 mins of driving. The new code is P057B (brake pedal position sensor "a" circuit performance). I don't know yet if this is something was introduced by the "fix" or it wasn't showing up earlier because the P0808 was firing. Will be researching.

Jeep Wrangler JL 2021 JLUR (manual, 3.6L ESS) Won't Start Screen Shot 2021-03-05 at 10.53.18 AM


Jeep Wrangler JL 2021 JLUR (manual, 3.6L ESS) Won't Start Screen Shot 2021-03-05 at 10.53.18 AM


Jeep Wrangler JL 2021 JLUR (manual, 3.6L ESS) Won't Start Screen Shot 2021-03-05 at 10.53.18 AM


Jeep Wrangler JL 2021 JLUR (manual, 3.6L ESS) Won't Start Screen Shot 2021-03-05 at 10.53.18 AM
Not an acceptable fix, IMO. I would send those pics to JeepCares and make the dealer replace the harness. My $0.02. Also, CEL only started after their repair, so o wouldn’t even waste time debugging. Make them fix. Inspect repairs before taking delivery this time, since you know they are happy to make bandaid repairs.
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
Lol - I was going to suggest in an earlier post to inspect for a 3' blast radius around the path of the wiring harness, but I didn't want to sound like a dick - or at least more of one than I already have! IMO - this is par. There are some jobs you just need to do yourself if you want them done right.

You are correct to go looking for the brake sensor wiring diagram. Note on the diagram connector ID XY302A and XY303A for the clutch sensor. First - I wanted to see that these ID's were the same, signifying the same connector - ie, at least a 6 pin connector containing wires for both - that would be a smoking gun - but they are not. They could still be, as you don't know the origin of these wiring diagrams - or they could be two adjacent connectors that suffered the same fate.

GFL getting the location information for this connector anywhere but on TechAuthority subscription. Love to hear I'm wrong. This is where the rubber hits the road on a real world repair, and I've found this information deliberately removed from the USB manuals I've bought on TechAuthority.

The tech has isolated the problem as being between his jumper connections. That's where you need to go next, and you need to locate the brake sensor wiring as well.

Those bed-of-nails probes are perfect. Look for resistance and voltage drop on the wires on both sides of the connectors - start wide - PCM to sensor - and zero in on what I would bet money at this point is a connector that isn't seated correctly or doesn't have its individual pins set well in the connector shell. A good tech would find this and repair it in under 30 minutes, IMO, while a bad one might spend weeks then replace the entire wiring harness.
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
Looking quickly again at wiring diagrams for XY302A and XY303A - connectors for the clutch and brake position - both show high pin #'s - this is likely a big connector with a lot of wires. I am suspicious it's the same connector, but the wiring diagrams are not matched up.
 

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
 
Thank you both for your advice and suggestions. I am not going to take it back to the dealer. Not at least to this one. I don't want them to break more things that I'd have to fix. I already spent last evening glueing broken parts and sitting connectors that were left free hanging. They've disconnected a bunch of them and some still red tabs unlocked. Very sloppy job as far as I can tell.

@NBB - everything you've said and warned about turned out to be true. I appreciate your guidance very much. I am also pretty sure that the issue is either in the harness or one of the connectors. I am going to try check continuity between the connector they've messed with and the PCM. My understanding I have to disconnect the PCM harness in order to do that. The hardest part is getting to it, but I believe there was a video on YT on how to do that.
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
My understanding I have to disconnect the PCM harness in order to do that.
You shouldn't need to disconnect anything to locate the problem. You need to pierce the wires with a probe, or IMO you'll make yourself miserable looking for possibly intermittent issues that come and go as you move things around.

Once you've located the connector giving you a problem and you're certain, then yes, you need to open it and carefully inspect the suspect pins. Look for pin not seated in shell or bodies not seated together correctly.

The vehicle is too new for corrosion issues, but seating and re-seating often fixes corrosion by "wiping" it off the metal, then you lube with dielectric grease.

The next level above that is the solder or crimp to the individual pin is faulty - this is next level stuff to locate and repair - you need a special tool to push the pin out of the shell, then you recrimp and/or solder the wire to the pin and reinsert the pin back into the shell.
 

OldGuyNewJeep

Well-Known Member
First Name
Don
Joined
Sep 21, 2017
Threads
85
Messages
3,816
Reaction score
6,828
Location
CT
Vehicle(s)
2018 Wrangler JL, 2016 Yukon XL
Lol - disagree - how would you really expect that to turn out given what's already happened? I'm thinking very poorly.

My first rule of dealing with idiots - is to stop dealing with the idiots.
Yes, which is why I am suggesting JeepCares... so you can have them make an appt with another shop. They will give all the details.

Many shops will cut corners on warranty work if they can, unfortunately.

That’s just my, opinion, though. I do not like fixing vehicles that are under warranty.
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
I do not like fixing vehicles that are under warranty.
Neither do I, but unfortunately I've generally found it to be the lesser of problems compared to dealing with damage from incompetent mechanics. It's a rough trade - the guys smart enough for it, IMO, are also smart enough to go find better, higher paying jobs. What's left are savages and heathens. IMO.
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
Okay - mind ticking - because I design and debug for a living and love it - tech opened a connector containing both the brake and clutch position sensors - could have been done with the job if he'd just reseated it better - but instead he busted off the locking tab and did a poor job of reseating - now you have the brake trouble code. The clutch sensor wire has been routed around this connector. Just a guess.
 

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
 
Good point. In case this helps someone in the future, here are the location of XY301A and XY302A connectors in the front passenger well (behind plastic molding cover).

IMG_2166.jpg
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
If you're okay with the bypass wiring - then you might almost be done here.

Assuming that's his writing, then it's clear the tech disconnected the brake sensor wire at this connector. Since he replaced the PCM, the problem could be there as well, but you need to do things 1 step at a time here - fix this one first and wait to see if code reappears before messing with PCM connector.

IMO - get some dielectric grease. It will lube the connector, allowing you to get it in more firmly. Connect and disconnect a few times to "wipe" any possible corrosion issues. It doesn't appear from photo any locking tabs were damaged. Firmly reseat and lock.

EDIT - thoroughly inspect the pins - that they are seated in the shell. Looks like you might need a small inspection mirror to see into the mating connectors.
 
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
 
If you're okay with the bypass wiring - then you might almost be done here.

Assuming that's his writing, then it's clear the tech disconnected the brake sensor wire at this connector. Since he replaced the PCM, the problem could be there as well, but you need to do things 1 step at a time here - fix this one first and wait to see if code reappears before messing with PCM connector.

IMO - get some dielectric grease. It will lube the connector, allowing you to get it in more firmly. Connect and disconnect a few times to "wipe" any possible corrosion issues. It doesn't appear from photo any locking tabs were damaged. Firmly reseat and lock.

EDIT - thoroughly inspect the pins - that they are seated in the shell. Looks like you might need a small inspection mirror to see into the mating connectors.

The connectors appear in perfect condition. I doubt there would be any rust in the dry SoCal climate, but will do as you said. Ordered this dielectric grease. Hope that's the right kind.

Checking connections as we speak. My understanding from the wiring diagram, the break pedal position sensor, unlike the clutch pedal position sensor, does not talk to the PCM. The wires lead to the Anti-lock Brakes Module instead.
 
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
 
More wrong doing by the dealership. Apparently, they don't know how to test the clutch pedal interlock switch.

IMG_2171.jpg
 

NBB

Well-Known Member
Joined
Mar 10, 2019
Threads
0
Messages
168
Reaction score
179
Location
Boulder
Vehicle(s)
21 JLUR
The connectors appear in perfect condition. I doubt there would be any rust in the dry SoCal climate, but will do as you said. Ordered this dielectric grease. Hope that's the right kind.

Checking connections as we speak. My understanding from the wiring diagram, the break pedal position sensor, unlike the clutch pedal position sensor, does not talk to the PCM. The wires lead to the Anti-lock Brakes Module instead.
There is always corrosion, it's just a matter of degree and how long it takes to form. There's a reason for using gold on critical connections.

The grease you ordered looks fine, but seems overkill - I use "permatex dielectric grease" - shocked if it's not at local auto parts store. Every single electrical connector I open on a vehicle - if it's not greased already, I add this stuff.

Good catch - I didn't immediately catch that they go to different modules - likely the reason for 2 different connectors.
Sponsored

 
 



Top