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

[demisx]

Hello fellas. A couple of days ago I got into my 2021 4-dr. JLUR (manual, dual 12V batteries with ESS), pressed the clutch, pushed the start button, and … my almost brand new “since 1941”’ icon will not start. And, of course, this had to happen right before our planned weekend trip.

Here is what happens when I try to start:

1. I push the start button to switch to the ACC mode. Everything powers up and loads as normal.
2. I then press the clutch and push start button to start the engine. I hear a click and then Uconnect 8.4” screen goes black. There is no attempt from the starter to turn over.
3. I let the start button go and the Uconnect screen come back on again.
4. I try this two more times and the same thing happens each time.
5. Here is the video that shows this process (3 start attempts total)

I’ve spent two days going through our forum and trying different things, but no luck. The first thing was to check both batteries. I’ve tested them in isolation and both shown 12.xV voltage. I left the battery tender overnight and brought the charge in both to green. I’ve tried to jump start with a battery pack - still no luck.

Any idea what maybe wrong? Thank you all.

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[Rhinebeck01]

Wild wild guess...

Jeep Wrangler (JL) Clutch Pedal Position Sensor is a muck..

 

[eck]

Wild wild guess...

Jeep Wrangler (JL) Clutch Pedal Position Sensor is a muck..

That was my first thought too. It looks like it's behaving exactly the same as I would expect if you were hitting the button without pressing the clutch in at all.

 

[Sorbs]

It may be your key. The "start" button may need to be reprogramed so try your second key. If that doesn't work the dealer can try to reprogram the ignition module. Note: if your dealer hasn't seen this issue before they will replace everything. PCM, ECU, batteries...and then order a new key from the factory to reprogram your module. Ask them to start with the ignition module first. It might save you time and their hassle getting those parts, only to figure out it was the ignition module, and a quick re-keying process.

Good luck!

 

[Rhinebeck01]

It may be your key. The "start" button may need to be reprogramed so try your second key. If that doesn't work the dealer can try to reprogram the ignition module. Note: if your dealer hasn't seen this issue before they will replace everything. PCM, ECU, batteries...and then order a new key from the factory to reprogram your module. Ask them to start with the ignition module first. It might save you time and their hassle getting those parts, only to figure out it was the ignition module, and a quick re-keying process.

Good luck!

I was gonna ask him if he had tried his other Fob..... indeed this could also be the issue...

 

[demisx]

That was my first thought too. It looks like it's behaving exactly the same as I would expect if you were hitting the button without pressing the clutch in at all.

I've just tested starting without pressing the clutch pedal and it behaves slightly different:

1. The U-Connect screen doesn't turn off
2. I don't hear any click or any sounds coming from under the hood like I do when the clutch is pressed

I'll see if there is a way to bypass clutch sensor altogether.

 

[eck]

I've just tested starting without pressing the clutch pedal and it behaves slightly different:

1. The U-Connect screen doesn't turn off
2. I don't hear any click or any sounds coming from under the hood like I do when the clutch is pressed

I'll see if there is a way to bypass clutch sensor altogether.

https://www.jlwranglerforums.com/JL-Wiring-Diagrams/TRANSMISSION---MANUAL---3.6L.pdf is going to be your friend. I'm not sure which combination of clutch position sensor and clutch interlock switch it's referencing at startup. Interlock for sure, I don't know if it cares about the absolute position or not.

 

[demisx]

It may be your key. The "start" button may need to be reprogramed so try your second key. If that doesn't work the dealer can try to reprogram the ignition module. Note: if your dealer hasn't seen this issue before they will replace everything. PCM, ECU, batteries...and then order a new key from the factory to reprogram your module. Ask them to start with the ignition module first. It might save you time and their hassle getting those parts, only to figure out it was the ignition module, and a quick re-keying process.

Good luck!

Thank you. I've just tried it with my 2nd key. Same result. I'll keep in mind about the "reprogramming the ignition module".

 

[Sorbs]

Oh yeah, ask me how I know...

Thank you. I've just tried it with my 2nd key. Same result. I'll keep in mind about the "reprogramming the ignition module".

Also, if you've been behind the trim panel and unplugged the "start" button to get the trim panel out of the way, that's a "security" feature. It kills the ignition module, hence, why it needs to be re-programmed.

 

[demisx]

Oh yeah, ask me how I know...

Also, if you've been behind the trim panel and unplugged the "start" button to get the trim panel out of the way, that's a "security" feature. It kills the ignition module, hence, why it needs to be re-programmed.

No, never took down any front trim panels. I've only disconnected both batteries before for a few mins trying to restart ECM module (if not mistaken on the name). It was suggested in one of the threads.

 

[Archie PJ]

Almost sounds like an issue with the clutch switch itself--maybe shorted--because of the changes you get when you press the start button with and without depressing the clutch. Just a WAG. Good luck.

 

[demisx]

A little more detail on the 2 mods I've done since last time I was able to start it:

1. Added a fuse block panel under glove compartment with 6 AWG 80A fused wire from the main battery positive https://www.amazon.com/gp/product/B00WM2MWQ4/ref=ppx_yo_dt_b_asin_title_o06_s00 with auxiliary switches "ignition on" wire controlled solenoid https://www.amazon.com/gp/product/B0064MX7US/ref=ppx_yo_dt_b_asin_title_o04_s00. The installation went smoothly without any sparks or any noticeable abnormalities. I did disconnect the whole thing once I've experienced the start problem. Just to be safe.

2. Installed Rugged Ridge rear light guards https://www.amazon.com/gp/product/B07RN6V95S/ref=ppx_yo_dt_b_asin_title_o00_s00 where I had to disconnect and re-connect rear lights.


Also, I had the Jeep sitting in the garage for 2 days without doors and with keyfob inside.

 

[Jebiruph]

A little more detail on the 2 mods I've done since last time I was able to start it:

1. Added a fuse block panel under glove compartment with 6 AWG 80A fused wire from the main battery positive https://www.amazon.com/gp/product/B00WM2MWQ4/ref=ppx_yo_dt_b_asin_title_o06_s00 with auxiliary switches "ignition on" wire controlled solenoid https://www.amazon.com/gp/product/B0064MX7US/ref=ppx_yo_dt_b_asin_title_o04_s00. The installation went smoothly without any sparks or any noticeable abnormalities. I did disconnect the whole thing once I've experienced the start problem. Just to be safe.

2. Installed Rugged Ridge rear light guards https://www.amazon.com/gp/product/B07RN6V95S/ref=ppx_yo_dt_b_asin_title_o00_s00 where I had to disconnect and re-connect rear lights.

I would disconnect the electrical stuff you added and see if it will start. Others have posted about not being able to start after connecting stuff to the aux switches.

 

[demisx]

I would disconnect the electrical stuff you added and see if it will start. Others have posted about not being able to start after connecting stuff to the aux switches.

Yep, that was the first thing I did. Rolled back all my added connections.

 

[Jebiruph]

In your video it looks like the check engine light is flashing after the failed start. Is it and is there a code?

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