i wanted to let folks who drive pickups that you can tap a convenient wire in the dash for your painless brand dual-battery setup, which needs a +12v source that's only powered in ON and START modes. this may apply to other solenoid-operated isolator/combiners, and to other models such as 4R in this year range as well. ymmv.

here's the switch for mine:



to remove that panel enough to do the work, undo three or four screws with obvious formed holes in the plastic around on both sides of and kind of below the steering column. another is a larger 10mm bolt. i also took out the three screws above the instruments. carefully pry the panel loose enough to see the rear of the clutch-start switch. the black and yellow wire going into it (it's on the left side for me) is the one to tap.

due to the shortness of that black/yellow wire, clamping the T-tap on there is kinda tough, but it'll work with some effort. the only other exposure of that wire i found is in a big bundle of wires below the key, and it's even tighter there. i did that part of the install a few days ago and completed the cable-routing to the starter solenoid with a little help today, so was finally able to confirm success on the tests in the painless installation guide.

 

I know this is an old thread but I'm going to bump it to say thanks! Great tip on the wire to save some time!!!

 

What exactly is this. I have run dual batteries before.. I never had a switch or anything just wired them in line... What's the switch supposed to do?

 

I have the same toggle switch with my Painless dual setup.
The switch isolates the batteries via solenoid so they are not both on at the same time, or you can have them power at the same time.
Also turns off the charging for the second battery in the middle position.