Totally screwed: Installed new Auxiliary Battery and now truck won’t start with multiple errors

[Lucky1]

Interesting info here. 2 weeks ago mine wouldn't start in the driveway. Wipers also had a fit with the truck not on and it told me it wasn't in park at one point! I did use the jump pack and got the truck started with the jumper in boost mode. Put it in the garage and began working..... pulled both batteries from the truck, going thru the top down method. Both batteries read 10.84 volts. Taped of the Aux battery cables, pulled the fuse 42, and replaced the main battery. No issues to the truck at all at this point. Running just fine with one battery. Even for 3 days with no batteries in the truck it retained all the radio presets, clock, temp settings, phone pairs, and dash settings Although i did notice, I have the rough country led headlights and I have lost the "x" pattern daytime running lights. Need to go back in and see what I missed there.

Sponsored

 

[Gladiator Brad 704]

I also changed my aux. battery thru the wheel well. So much easier than thru the top. Just get new plastic rivets (3) and a few of those push in plastic pins from Amazon (5 or 6). Disconnect the big battery first.

 

[Jackpaul]

The clear solution for this issue is to trade in your vehicle on a diesel model. You see, the trap door for the Aux battery is under the main battery...problem solved.

Yessir!!!

 

[Papa Bear]

Went through the top. Disconnected primary battery, pulled it out, popped cover to fuse box and removed the 4 bolts (7mm) then lifted the PCM up and there’s a tray there with 3 more bolts (two 10mm and one 7mm), pulled those and lifted tray to find 4 more bolts (10mm) then that real eases a protective tray which houses the auxiliary battery. I don’t have a problem at to test if the auxiliary battery was good from the dealer so I cleaned terminals and reused the studs for “posts” off the old battery. When I did each step in reverse and got to the PCM and Fuse box, the four 7mm bolts have to be hand tightened very carefully. The first time I under tightened them and that caused all the problems. When I resecured them tighter I had to make sure the four bolts all fit perfectly.
Truck ran fine for about 400 miles then the Christmas tree of dash lights all returned. The ABS, ESC, service 4 wheel drive, sway bar, etc. When I got to a safe place and put it on park, I was unable to get vehicle out of park. I took to AutoZone and the codes they ran stated ABS sensor and vacuum pump needed to be replaced…this could be legit but I have no way of knowing. Called my Jeep dealer parts manager and he said, “getting an AutoZone OBD2 reading is like going to a palm reader, vague and not always accurate or revealing.”
I lifted the hood and could hear the sound of a small motor trying to kick on (buzzing whirring sound) it would go for about 5 seconds then kick off, then come right back and repeat the sound at least 8 times before I used my Tazer to clear all DTC codes. Everything cleared except ABS, that one didn’t want to respond! And the service 4WD light remained in as well.
When I turned vehicle off for a minute then turned vehicle back on, I had no power steering.
For the life of me I couldn’t pinpoint exactly where that whirring was coming from. I’m starting to think a couple issues here all sensor related and possibly the vacuum pump is failing.

Did you go through the wheel well or do it correctly by removing the main then access under fuse box?

e to

 

[IanNubbit]

Did you go through the wheel well or do it correctly by removing the main then access under fuse box?

You got the correct and incorrect way to replace the battery swapped there but good question either way

 

[Fpolanco]

Love this post!! I’m just trying to learn here so be gentle.

In order to avoid being stranded or dealing with any aux battery issues, it looks like I can go one of two ways:

1) Genesis dual battery install if I want to keep/increase battery capacity

or

2) disconnect the main battery, remove the aux battery, remove the fuse, reconnect the main battery and run as a single battery vehicle.

Does that sound about?

 

[Lunentucker]

Love this post!! I’m just trying to learn here so be gentle.

In order to avoid being stranded or dealing with any aux battery issues, it looks like I can go one of two ways:

1) Genesis dual battery install if I want to keep/increase battery capacity

or

2) disconnect the main battery, remove the aux battery, remove the fuse, reconnect the main battery and run as a single battery vehicle.

Does that sound about?

All you really have to do is disconnect the ground cable from the AUX battery at the main ground, and remove F42.

Tape the disconnected ground to prevent incidental contact and grounding.

You can leave the AUX where it is and not have to deal with the fender liner or the fuse box, or you can go all in and take it all out.

 

[Gladiator Brad 704]

As soon as my extended warranty expires I am going to go the dual Genesis route. Great system but unbelievably expensive.

 

[Papa Bear]

Anyone had to replace any ABS sensors or the vacuum pump yet? Very curious to see if the symptoms you experienced prior to doing so mimicked any part of what I am describing.
The auxiliary battery is where most of the advice I received pointed me towards but having swapped both batteries and still having the same electrical catastrophe as before, it clearly wasn’t the batteries.
Another source recommended I take a look at the CAN Bus star: I did a visual inspection but nothing looked out of place and the vehicle functioned perfectly until about 5 months ago when the aforementioned dash lights and behavior of the Jeep became a regular occurrence.
Now I literally cannot drive the truck without this happening at least once per trip and it’s usually much more. Today alone it has acted up 3 separate times in the course of 14 miles. Ridiculous and I feel like I’m chasing my tail. No one seems to have the same exact problem as mine and therefore no definitive answer has come to light. I’m gonna keep holding out that this will reach the right JT/JL owner who knows what I’m dealing with and more importantly, how to rectify the problem.
God bless!

 

[am1978]

Anyone had to replace any ABS sensors or the vacuum pump yet? Very curious to see if the symptoms you experienced prior to doing so mimicked any part of what I am describing.
The auxiliary battery is where most of the advice I received pointed me towards but having swapped both batteries and still having the same electrical catastrophe as before, it clearly wasn’t the batteries.
Another source recommended I take a look at the CAN Bus star: I did a visual inspection but nothing looked out of place and the vehicle functioned perfectly until about 5 months ago when the aforementioned dash lights and behavior of the Jeep became a regular occurrence.
Now I literally cannot drive the truck without this happening at least once per trip and it’s usually much more. Today alone it has acted up 3 separate times in the course of 14 miles. Ridiculous and I feel like I’m chasing my tail. No one seems to have the same exact problem as mine and therefore no definitive answer has come to light. I’m gonna keep holding out that this will reach the right JT/JL owner who knows what I’m dealing with and more importantly, how to rectify the problem.
God bless!

Yes, on my 2018 JLU Sahara 3.6, under warranty. https://www.jeepgladiatorforum.com/forum/threads/ess-and-esc-lights-on.67291/post-1106909

 

[Vtur]

I recommend you to go back and recheck all the connections that you had disconnected during the battery replacement. Check for damage wiring and connector pins. Tapping, wiggles and shaking the fuse box/harness while idling and see if it triggers any cel.

 

[Papa Bear]

The code they seems to always be present during and after is U0121 and P0415.
U0121 ALWAYS present during problem.

 

[Papa Bear]

 

[Lost1wing]

ABS Module faults are commonly associated with low battery voltage. I'm still thinking along the line of the battery power or ground connections. Maybe there is another ground on the engine or transmission that is loose.

 

[Lost1wing]

Ground G907a has a service bulletin on it for u0121. It is the ground for the ABS module and the PDC. There is also another service bulletin on ground G907a for multiple U type codes.​

S2208000025​

S2208000085​

Sponsored