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Hey guys, I started a little fun project this weekend to put a dedicated switches 12v outlet in the back of my 87 runner. I decided to use power from the hardtop harness plug because I have a softopper. I have 12v at the wires I am using, see pics, but when I hook up my power bank it drops to 7v?? I thought something was bad in the power bank so I bought another one. Same story. If I run ONLY the car outlet 12v item, I get a solid 12v. I I try and add in the usb or the switch, it drops. I can’t figure this one out. Any trouble shooting tips or ideas from anyone?
The wires I’m using from the plug pigtail The pigtail for hardtop Jumper harness I made for my power bank Outlets added
I’ve realized that the voltage seems to drop from the truck when a load is applied.. the green yellow wire appears to be possibly for the wiper power. There most be something in the trucks harness the regulated voltage depending on draw? Looks like this may all be for nothing and I’ll need to run a dedicated power line
Without a wiring diagram its really a guessing game on the connector pinouts. Since I have a 2nd Gen I can't compare mine. I did a quick Google search without great results: One post here for a different year shows the G-Y wire as the Wiper Docked Sense Switch but that was on a connector that included the Rear Widow motor wiring. That diagram also showed Switched 12V on a Red lead and Direct Battery on a Blue lead.
What else is the connector used for? Dome light etc? Unless that connector is for something that gets power all the time (has its own local switch) you may have to run dedicated wiring. Depending on how much your max current draw is at that panel, dedicated heavier gauge wiring might be a better idea anyway.
why not utilize power from wires running to the tailgate? the window key switch will have battery power. you could run a short wire from the control box behind the drivers seat to your power bank.
why not utilize power from wires running to the tailgate? the window key switch will have battery power. you could run a short wire from the control box behind the drivers seat to your power bank.
Yes, permanent key off power to be got at the rear window relay box.
Permanent key-off power terminates at the rear window relay box in the drivers side panel, behind the front seat.
The rear window key switch in the tailgate makes ground to either an up or a down pin on that relay box to facilitate window up or down.
There is no continous 12v+ power to the rear key switch.
Use your multimeter to watch the current draw. "Power Banks" can draw a hefty amount of current. 18ga wire should be fine for 5amps, throw in a 15amp load and some tired connections and a 5v voltage drop wouldn't shock me.
As a sanity check, hook up your power bank directly to the battery and watch the voltage. If the battery holds it up fine, you've got some weak wiring. I wouldn't bother searching for the worst connection; just install a run of 14ga dedicated to your outlets.
[On my '94, the bed is insulated from the rest of the truck. In other words, no "body ground." The taillights have their own dedicated wire for ground. Your '87 may be different, but I wouldn't count on a good ground to sheet metal.]
Try using a local body ground and the + 12v wire. Results same???
afyer my post I thought about using a different ground, same result. I decided to another route, and used the constant 12v on the passenger side speaker plug (was unused in my rig) and I added a switch. Never could figure out the yellow/green wire voltage drop. So strange.
Use your multimeter to watch the current draw. "Power Banks" can draw a hefty amount of current. 18ga wire should be fine for 5amps, throw in a 15amp load and some tired connections and a 5v voltage drop wouldn't shock me.
As a sanity check, hook up your power bank directly to the battery and watch the voltage. If the battery holds it up fine, you've got some weak wiring. I wouldn't bother searching for the worst connection; just install a run of 14ga dedicated to your outlets.
[On my '94, the bed is insulated from the rest of the truck. In other words, no "body ground." The taillights have their own dedicated wire for ground. Your '87 may be different, but I wouldn't count on a good ground to sheet metal.]
no wiring issues on this truck. Outlets checked out fine. From my diagrams it looks like the yellow green wire is for the wiper. I had a solid 12v when not hooked to anything.. or with just a single cig outlet style power outlet on it. Hook up the other outlets and power drops to 7v. So weird. Ground are good. I ended up moving to passenger side. There is a plug that goes to the speaker preamp that I wasn’t using. I ran it to a switched power bank and it works great now.
will post some pics and results tomorrow. The mystery of the yellow/green wire remains!
Are those White with Blk stripe and Green with yellow stripe?
G-Y is input for rear window control. It's not a power supply line. It's meant to float (12V) or be shorted to ground (zeroV) via tailgate key switch.
Best practice would be to run the dedicated power line fused as closed to battery as possible.
White with black stripe is body ground but you'd be better off leaving that alone and best practice would be taking ground directly from body grounding bolt. There should be one on pinch-weld along which the loom runs, near top-off switch.
Last edited by RAD4Runner; 06-19-2022 at 04:01 PM.
06-18-2022, 02:52 PM
