Guide to Disabling Auto Start Stop + Removing the Auxiliary Battery on a 2025 RAM 1500 SO/HO

[firemedic10584]

Usually my previous RAMs would turn on, but then turn off after a little bit if a check engine or low fuel light was on.

Yes, you’re correct. I did it again later and it turned off after probably 10-15 seconds. So it’s still functioning as designed I suppose.

 

[Carlos.33193]

For sanity, am I missing F52 fuse or?

 

[bigdodge]

For sanity, am I missing F52 fuse or?
View attachment 211733

this one was a few years ago

 

[Jimmy07]

For sanity, am I missing F52 fuse or?
View attachment 211733

Level 2 driver assist trucks don’t have fuse 52, because they have a different dual battery switch module.

Level 2:


Non-level 2:


Level 2 trucks also have 2 intelligent battery sensors, one for each battery:


While non level 2 trucks only have one IBS for both batteries:

 

[RedFred]

Good info here. I can see myself trying this in the future once it warms up outside or if any battery issues arise.

 

[Carlos.33193]

Proceed at your own risk.
I went back and re-did my AUX removal to fix my previous mistakes.
Seeing as how from everything I found the L2+ trucks don't have a PCR or fuse that can be easily bypassed, I went with my original approach.

I tied both IBS from main and aux - to the negative battery terminal, in my original removal I didn't realize i tied the aux battery - IBS to the main battery IBS output, so the main battery IBS was measuring the current draw of both which is what was probably causing my charging voltage to be 14.8 all the time. This was a mistake on my part. With this new method my charging voltage is 14.4 on startup and then drops to 13.8-13.9.

I then used a 50A fused wire link to jumper N3 (AUX Battery +) to N9 (Main Battery +), and disconnected the original N3 wire that runs to the AUX + and heat shrunk both ends just to keep it clean.

Everything is working as expected, with no OBD codes, and start-stop works also (although I will keep it disabled).

I used this to tie both IBS. https://www.amazon.com/dp/B09W24MCHD

Until a better, proven method comes out for the L2+ trucks I'll keep using this.

 

[70runner]

The cynic in me suspects many dealers will see a missing aux battery and refuse warranty service for an electrical issue. My experience, with a 21 Rebel and the current 25 Rebel, suggests a factor in electrical gremlin adventures with these complex networked vehicles is marginal battery condition caused by parasitic drain, modules which don't sleep soundly. The 21 had several electrical issues, including a 4x nominal parasitic drain the dealer couldn't track down. Put it on a trickle charger. No more gremlins. For the 25, I use the start/stop eliminator and trickle charger.

 

[Ram7081]

Here is my 2025 Ram with LV2. I see the F52. I read above they don't have it. I see it on mine.

 

[Carlos.33193]

Here is my 2025 Ram with LV2. I see the F52. I read above they don't have it. I see it on mine.

What trim is your truck?

 

[firemedic10584]

Update on mine after following the steps posted in the first post. My auto start stop does still in fact engage. It started back up fine when I turned the button off, but I thought this process eliminated that from engaging at all?

 

[Ram7081]

What trim is your truck?

Big Horn.

 

[Jimmy07]

Big Horn.

When the schematic refers to lv2+, it means the driver assistance level, not the trim package level. So, it’s referring to the hands free driving feature (not sure what exactly that has to do with the aux battery switching though).

 

[Ram7081]

When the schematic refers to lv2+, it means the driver assistance level, not the trim package level. So, it’s referring to the hands free driving feature (not sure what exactly that has to do with the aux battery switching though).

Thank you for clarifying.

 

[RedFred]

Update on mine after following the steps posted in the first post. My auto start stop does still in fact engage. It started back up fine when I turned the button off, but I thought this process eliminated that from engaging at all?

I thought so too. You followed all the steps and have the 3.0 Hurricane?

 

[firemedic10584]

I thought so too. You followed all the steps and have the 3.0 Hurricane?

Yep. Exactly as the steps he listed. When I drove it around after doing the initial battery swap, the start/stop did not engage at all, even with the AC off. I went out of town for a few days and today was the first time driving the truck again. It fired right up with no issues after sitting for about 4 full days. I was surprised when I came to a red light to hear the engine shut down. So not sure what happened, but it does in fact still work (unfortunately).

 

[firemedic10584]

And my truck is a 2026 Laramie...not sure if it's level 1 or level 2, but I had fuse 52 like he mentioned and I removed that during the initial battery swap.

 

[RedFred]

And my truck is a 2026 Laramie...not sure if it's level 1 or level 2, but I had fuse 52 like he mentioned and I removed that during the initial battery swap.

Maybe because you have a 2026? I'm not sure if there were changes made for the 2026 model, but I would consider putting everything back the way it was if the auto start/stop is still functioning.

 

[firemedic10584]

Maybe because you have a 2026? I'm not sure if there were changes made for the 2026 model, but I would consider putting everything back the way it was if the auto start/stop is still functioning.

I'm not experiencing any issues. I'm 99.99% sure there's no difference, as far as this modification is concerned, between a 2025 and 2026 truck.

 

[Dodge1Ram]

Yep. Exactly as the steps he listed. When I drove it around after doing the initial battery swap, the start/stop did not engage at all, even with the AC off. I went out of town for a few days and today was the first time driving the truck again. It fired right up with no issues after sitting for about 4 full days. I was surprised when I came to a red light to hear the engine shut down. So not sure what happened, but it does in fact still work (unfortunately).

Same result for me here. 2025 Rebel Hurricane SO Level 2 Group package. Removed Aux Battery, Replaced Main Battery with a 7H Diehard Plantinum 850 CCA AGM battery. Holds charge now for multiple days. Start Stop still works. Throws up check engine light related to the Aux Battery missing even though truck starts back up using the Main.

 

[turbom5]

Same result for me here. 2025 Rebel Hurricane SO Level 2 Group package. Removed Aux Battery, Replaced Main Battery with a 7H Diehard Plantinum 850 CCA AGM battery. Holds charge now for multiple days. Start Stop still works. Throws up check engine light related to the Aux Battery missing even though truck starts back up using the Main.

Does your aux battery negative have a sensor like the primary battery negative does ? This sensor is for battery monitoring and charging. My 25 rebel base not even level 1 does not have a negative lead sensor for the aux battery only the main. This is likely why you get the error since the sensor notices the aux battery isn't there.