Which fuse to tap?

[Golfnut]

I installed a business band two way radio in my 2024 Ram yesterday. Its a Laramie with Cummins. It does not have the upfitter AUX switches. I contemplated just going straight to the battery and trusting myself to turn the radio off when I know the pickup will sit for a while but I used my better judgement and put in a relay. For the switched power I tapped into the Heated Steering Wheel fuse. I'll probably be using the same relay or adding another on in the future for an air bag compressor. Is this fuse tap location ok?

 

[stillhere]

Can’t imagine it is not ok…I’m about to hook up a DC to DC charger for a battery in my bed tool box and am looking to tap a fuse as well. What fuse number is the heated steering wheel in yours? Is it in the engine bay or under dash?

 

[Golfnut]

The pickup is in a garage on the other side of my yard so I'm not going to go look but its in the engine bay fuse box. When facing the pickup it was towards the top left of the box.

 

[Brutal_HO]

Can’t imagine it is not ok…I’m about to hook up a DC to DC charger for a battery in my bed tool box and am looking to tap a fuse as well. What fuse number is the heated steering wheel in yours? Is it in the engine bay or under dash?

There are no fuses under dash in pre 25 trucks.

RAM_Fuses

docs.google.com

Thread 'In Cab Power FAQ -- AUX Switch power info -- Chassis power info'

Apr 1, 2022

This is a roll-up thread that should answer most if not all questions regarding power availability in the cab.

A lot of the credit for technical detail goes to @Jimmy07 without whose help and guidance much of this info would be hard to assemble.
There are other contributors, you know who you are. If you recognize a photo as one of yours, shoot me a PM and I'll add the credit.

PDC and AUX PDC Fuse worksheet: https://docs.google.com/spreadsheet...ouid=105565244363658163151&rtpof=true&sd=true
or here...

• Brutal_HO
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• Replies: 58
• Forum: Modifications and Accessories

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[stillhere]

I found a fuse in the engine bay I’m going to tap. 15 amp…it says spare on it but it’s live with acc on and dead with ignition off. Not sure what it would have been for originally.

 

[AH64ID]

Can’t imagine it is not ok…I’m about to hook up a DC to DC charger for a battery in my bed tool box and am looking to tap a fuse as well. What fuse number is the heated steering wheel in yours? Is it in the engine bay or under dash?

I found a fuse in the engine bay I’m going to tap. 15 amp…it says spare on it but it’s live with acc on and dead with ignition off. Not sure what it would have been for originally.

I think for a DC-DC I’d use the HAPP and a stand alone fuse, unless your charger is really small.

 

[stillhere]

It’s only 20 amp. The fuse tap is for ACC on signal wire, not positive source. The charger is hooked directly to the battery. I’m using HAPP for big 3 upgrade.

 

[AH64ID]

It’s only 20 amp. The fuse tap is for ACC on signal wire, not positive source. The charger is hooked directly to the battery. I’m using HAPP for big 3 upgrade.

20A in or 20A out?

The big 3 “upgrade” hasn’t been needed in over 20 years, save your money.

 

[stillhere]

I have 8ga wire running from my battery to the charger. It’s 20amp in and out. Only runs when the vehicle runs.

The fuse tap is for signal wire only to turn it on. Think blue wire for a stereo amp signal.

I had left over wire and stuff so the big 3 didn’t cost me anything. Plus, as I add more electronics to the truck I won’t have to worry about it. That said, I'm sure the wiring in this truck is already pretty beefy. The negative wires look pretty wimpy tho.

 

[stillhere]

This is what I’m doing:

Except, I’m running double 2ga positive and negative for the inverter.