Power & Ground Locations Hybrid 4Runner 2025+ (6th Gen)

[Trail4R]

In the 2025+ Toyota 4Runner Hybrid (6th Gen), the 12V auxiliary battery is located in the rear cargo area, specifically on the driver side behind the driver-side rear tire. This placement is different from the gas-only models, where the 12V battery is located on the passenger side in the engine bay.

You have a couple of options for alligator clip placement and grounding purposes in the hybrid engine bay. These power and ground locations are suitable for jumping, compressors, and other 12V accessories.

Power (Positive Terminal) In Fuse Box: ​

The positive (+) terminal for jump starting is clearly shown and labeled in the engine bay fuse box on the passenger side. Pop off the fuse box cover, and you will see the red cover to the positive (+) terminal. Flip the red cover open and connect your alligator clips.

Ground (Negative Terminal #1): ​

Toyota specifies that the negative (-) jumper cable should be connected to the metallic point in the engine bay, not directly to the battery.

“Connect the clamp at the other end of the negative cable to the metallic point shown in the illustration on pages 608–609 of the Owner’s Manual” - pictured above and below in the Toyota owners manual diagram section.

The owner's manual also says:

• Unpainted metal surfaces: Areas such as bolts or brackets attached to the chassis can serve as grounding points.
• Existing ground straps: These are often found connecting the engine block to the chassis and can be utilized for grounding.

Ground (Negative Terminal #2):​

If, for some reason, your jumper cables or your 12V accessory alligator clips do not reach the metal clip, you can use any unpainted metal surfaces like bolts or brackets attached to the chassis, which serve as solid grounding points. There are 12mm bolts along the inner fender wall in the engine bay a larger 17mm chassis ground bolt under the air intake inlet cover. Remove the air intake inlet cover, and you will see a big black bolt that will provide another suitable ground. This might be a good option if you have large alligator clips that won't bite the small 12mm bolts.

Power and Ground Location Diagrams from Toyota: ​

 

[stellarbuilt]

We’ve had a few of these hybrids in the shop already, and can confirm that Toyota really changed things up with the auxiliary battery location and under-hood layout on the i-FORCE MAX platform. The rear-mounted 12V battery definitely throws people off the first time.

For jump starting, powering accessories, or running a compressor under the hood, the fuse box terminal and the designated chassis grounds you listed are the go-to spots. We’ve used both grounding points (metal tab near the intake and the bolt under the air duct cover), depending on clamp size and what’s being powered. Both work.

If you're wiring something more permanent, like a dual battery setup, inverter, or accessory fuse block, we’d suggest routing clean power from the rear battery directly to a switch panel or new terminals in the engine bay. After your switch is mounted in the engine bay, you can then power all your 12V accessories from the switch.

We've been working on a 12V Relocation Kit for the 4Runner and Tacoma as well. We've installed a few on the 4th Gen Tacoma and will have a kit available for the 6th Gen 4Runner soon as well.

Feel free to reach out to StellarBuilt in Sacramento if anyone needs help with a full 12V system build. We're always around if you have any questions.

CONTACT - Stellar Built - Off-Road & 4x4 Fabrication Sacramento, CA

stellarbuilt.com

 

[Farzad_k]

We’ve had a few of these hybrids in the shop already, and can confirm that Toyota really changed things up with the auxiliary battery location and under-hood layout on the i-FORCE MAX platform. The rear-mounted 12V battery definitely throws people off the first time.

For jump starting, powering accessories, or running a compressor under the hood, the fuse box terminal and the designated chassis grounds you listed are the go-to spots. We’ve used both grounding points (metal tab near the intake and the bolt under the air duct cover), depending on clamp size and what’s being powered. Both work.

If you're wiring something more permanent, like a dual battery setup, inverter, or accessory fuse block, we’d suggest routing clean power from the rear battery directly to a switch panel or new terminals in the engine bay. After your switch is mounted in the engine bay, you can then power all your 12V accessories from the switch.

We've been working on a 12V Relocation Kit for the 4Runner and Tacoma as well. We've installed a few on the 4th Gen Tacoma and will have a kit available for the 6th Gen 4Runner soon as well.

Feel free to reach out to StellarBuilt in Sacramento if anyone needs help with a full 12V system build. We're always around if you have any questions.

CONTACT - Stellar Built - Off-Road & 4x4 Fabrication Sacramento, CA

stellarbuilt.com

On the dual battery setup, when tapping from the rear battery to a device that charges the dual battery, wouldn’t it be the same as tapping directly off the DC-DC converter that is also attached to the rear battery to charge it? Would you know if attaching a 35 amp REDARC DC-DC charger to the rear battery would draw from the battery or from the DC-DC converter?

Thanks

 

[stellarbuilt]

If you're running a REDARC DC-DC charger to the rear battery - it's still pulling power from that battery. It's not bypassing that starter battery and pulling power from another source. The starter battery is still a traditional 12V lead-acid starter battery. You connect terminals to that battery and it pulls power from that battery. What is your goal? Just a dual battery setup? If so, you're perfectly fine running a REDARC DC-DC charger to the starter battery.

 

[Farzad_k]

If you're running a REDARC DC-DC charger to the rear battery - it's still pulling power from that battery. It's not bypassing that starter battery and pulling power from another source. The starter battery is still a traditional 12V lead-acid starter battery. You connect terminals to that battery and it pulls power from that battery. What is your goal? Just a dual battery setup? If so, you're perfectly fine running a REDARC DC-DC charger to the starter battery.

Thank you for the note. Yes, the goal is to have a dual battery system similar to what I had in my 5th Gen.

According to their tech support, REDARC stops pulling power at 12.7 volts. It requires more than 12.7 volts to pull power "The BCDC1225D features a start battery isolation circuit, turning on at 12.9Volts and then off at 12.7Volts..." The rear battery when vehicle is not in Ready mode shows 12.0 volts. When vehicle is in Ready mode the voltage reads 14.1 volts. If connected, the REDARC will only pull when the vehicle is in the Ready mode.

The rear battery itself is part of a circuit that feeds 4 other fused lines while powered (or charged) by the built-in DC-DC converter. The READARC is added in series to the overall circuit. It is hard for me to think if the REDARC is pulling from the battery while the battery is pulling from the Converter or not. Similar to my 5th Gen 4Runner where I actually was getting the power from where the alternator connected to the battery - not really sure what I was drawing from but if from the battery, then the alternator was compensating for it. In case of the 6th Gen if the power is drawn from the battery by the REDARC then the converter is putting that power back into the rear battery.

My diagram is attached. I have a feeling the converter is fused at 200A.

 

[HOTTSistotle]

Im in the process of buying an off road premium i force max but I need a specific answer and hoping this thread is the place for it. I run a dielectric unit that anplifies the current up to 100kv to test insulation on construction and electrical equipment off the battery of my current 2019 tundra. I attach a 50v inverter to the battery and plug the controller box into that. A grounding wire from the amplifier to the truck is attached to a grounding bolt in my engine bay that the battery also grounds to. Is this possible to do with the i force motors without frying the hybrid battery. The dealership hasn't been the most helpful so far and this was the closest ive seen anyone talking about this. Thanks for the help in advance

 

[Farzad_k]

Yes, the dealerships don’t want to get into these things, I am afraid. I am still waiting to hear back from their expert on another electrical question.

Good luck.