Help - Gladiator throwing all the codes

Clubbs

Well-Known Member
Joined
Jun 15, 2008
Location
Blounts Creek
My son's 2020 gladiator wigged out while driving last Wednesday. 12 codes about lost communication with various engine, chassis, and trans computers. All sorts of dash light, wipers going bazurk etc.

Told him to take it to the dealer figuring it was some can sensor they could find easier than me. They said the batteries were bad (small one has been disconnected for years). So I replaced the battery and it seemed fine until yesterday.

Did not start as quickly seemed to catch and then stop starting like you turned off the key. Hit the button again and then it stated but couldn't move the shifter to drive.

Battery is still good, alternator is good. Several codes related to brake system. Thinking it's the break pedal sensor switch thing due to it's not starting or shifting and this all started after he left a stop sign. Maybe the low batt voltage sent to much current through this sensor thing???

Is the brake pedal position sensor a common fault on these jku / gladiators?

All can connections behind the glove box look good, all dry, never had the roof of this thing. Under hood seems fine, no loose connections, pretty clean low mileage vehicle... Only been wheeling once
 
I don't know much about JK/Gladiators, but that all points to a corroded or loose ground in my mind (or maybe ECU connections). The stronger battery is just bridging the gap better with stronger voltage or cleaner connections.
 
My 2015 jku did this a few years ago. Cut out on me going down the road, dash lit up. Turned out to be the ground at the chassis.
 
Used a different scanner to test various sensors. Brake position sensor and all others I could find and think to test are reporting as they should. The small aux battery has been disconnected for years via the top side and pulling fuse number 42, but actually removed it to verify there's nothing going on there. Pulled major plugs apart checked pins and hosed them with wd40. No dash lights and all seems normal again, but it's still storing 8 codes that I can't clear. Going to run it around today and see what happens.
 
rockmafia said:
Replace the green canbus connector behind the glove box.

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I don't see how that block can go bad, but the CAN network does seem to be going nuts. Asked my son to pick one up at the dealer today. I don't imagine that's an AutoZone part...
 
Clubbs said:
I don't see how that block can go bad, but the CAN network does seem to be going nuts. Asked my son to pick one up at the dealer today. I don't imagine that's an AutoZone part...
Click to expand...
Search it. There are loads of complaints about it going bad. Mine did the same thing in Colorado, I had a spare and fixed it in about 10 minutes. You can also unplug each thing from the canbus to trouble shoot it, thats why they put it there.
 
Noel said:
@TJody didnt you have something like this with your jl
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Yep, you would be driving down the road and the whole dash would light up like a Christmas tree, sometimes I would even loose power. Green cambus block for some stupid reason the jlu glove box sets right on the wires when closed , I now keep a spare with me at all times and glove box stays empty.
 
Replaced it tonight. Tried to clear codes that didn't work. Unhooked the battery for awhile and tried again. Got the U0001 code and U0121 code still. That's better than 8 codes. Main CAN and the abs module if I remember right.

We'll drive it around some more and see what happens I guess. Thanks for all the replies, I never would have thought to replace that piece.
 
benXJ said:
oh man.
canbus
2 batteries
christmas tree dash
brake position switch?!

oh how the mighty have fallen

I thought this was a offroady jeep?!
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For real - me too.

It's going to Ivy Branch this weekend to follow the old sarge CJ around. We'll see.
 
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