I also want to allow the power passenger windows to be able to operate without the key to allow adjustments during camping, etc. A couple questions:

- If I wire in a switch to put 12V at terminal 1 to energize the relay would I need to add a diode to that it doesn't energize terminal 2 of the ECU?
- I thought about simply jumping terminals 3 and 5 of the PWR window relay. I realize due to its location it is not convenient to reverse this so it would need to be considered semi-permanent. What are the consequences of just bypassing the relay? Is it possible for this to run down the battery somehow?

Can't help you without knowing year of the truck.

1999

First, don't put any good little 12V+ source there, as it will connect to the PWR fuse in normal operation. so you need to tap THAT fuse. You don't want to bridge two fuses.

Second, as to the diode question, the honest answer is I don't think so. The issue is the modules, such as the Body ECU, are not detailed as to what the internal wiring is. We have to guess. That terminal 2 is not a power source for the module. It simply is an exit for the PWR feed when the Body ECU thinks it is time to power up the windows, as in the key is on or during the magic 43-second stay-on time after the key is turned off. It is either a mechanical mini relay or its semi-conductor equivalent. In either case, 12V+ applied to T2 in the off state should just dead end there. But, without circuit details, I can't be absolutely sure.

Third, I don't know about the draw from a full-time bypass. The master switch is really a computer module, and it may have a very small power draw when not in use. I doubt it, but again, I can't see into the black box. It's easy enough to measure once you have done the mod. Even if there is, it would be the kind of thing that could go a few days before it drained a battery.

My suggestion for a non-permanent by-pass is find a dead relay, or sacrifice one, and pop the case off. then wire your by-pass inside the relay and put the case back on and install. One option is the mechanical approach where you simply wedge the contact arm in closed position. Then if you want to reverse, just swap the original relay back in.

Note that none of this applies to the liftgate window. That just ain't happening in a '99 unless you run wires all the way back to the liftgate because of the '99+ multiplex interface.

Thanks for the fuse advise. That sort of caution is not second nature to me, glad you said it.

Thinking with key off I could just put an ammeter across pins 3 and 5 where I want to bridge. If no action then I should be able to bridge either with a jumper or modified relay and not be concerned about battery drain.

A switch is the cleanest solution with the problem being then I have to wire in a switch

@TheDurk if I add a switch to energize the relay rather than bypass it I am concerned that it could cause a power draw. How much current do these little relays draw on the control side? Example if I press the button to put into camping mode and leave it all night will I have a problem?

No, not overnight. Not even close. I once had a Hella harness that was manufactured incorrectly and left my fog relay engaged 24/7. Truck still could go two weeks and then start. The coil will draw about 150mA, so in ten hours it will draw 1.5 amp-hours(Ah). A typical 24F battery for our trucks will run a capacity of 55 Ah, so to go to 50% will take 171 hours. Typical key-off drain for our rigs is about 50mA, so it is a bump, but not that big a deal.

Thanks Durk! Another question for you please...

I want to wire in the switch here:



As I look at pictures and wiring diagrams I see that the "Body ECU" piggybacks on the driver's side junction/fuse block. How do you suggest I get at those terminals?

Not a clue. Never had one open. I'd look at doing it at the fuse and at the relay socket Pin 1. No reason to go inside the Body ECU. I would think that more difficult.

Sorry for my ignorance here. How does one tap a fuse and a relay like that?

I've used fuse taps for the little fuses but not the big fuses (Jcase?) like the 30A and never a relay.

I can't give you an answer. If I were doing it, I'd look for something I could solder a wire to. There is no pretty solution that I am aware of.

Hi guys,
Been reading this tread and I think I came up with an idea.

The easiest way to do it is to put an ON/OFF switch next to the power window master switch (controls on the driver's door). It should be a regular switch that allows current to go from one wire to another like a bridge.

This bridging allows to bypass the relay in the diagram that is switched ON when you insert the key in the ON position, that gives power to the whole system.

You could technically just bridge both wires together without a switch, but I am not sure if there is a significant current draw, because of maybe another device being spliced at the hexagonal splice points on the diagram.

My opinion is that there probably isnt, but just to inform you guys to check with a multi meter for AMP draw, so you don't find the battery drained.

Here is the diagram:



First check for 12v on PIN 3 (blue wire) of the master switch plug pictured in the diagram with the ignition switch in the OFF position.

Then, check that there is no 12V on PIN 10 (blue/red wire) on the same plug, when ignition switch is in the OFF position, and that there is 12v when the ignition switch is in the ON position.

If that so, the you can proceed with connecting an ON/OFF switch to connect those two wires.

You can drill a hole in the master switch bezel and install the switch there, just make sure that the switch can handle more than 30 amps, as that is the current rating of the fuse in that system. Otherwise in case of a short, the switch may become the fuse and burn out.

Should I add a disclaimer - compare that the diagram wire coloring IS the same as that on the 4Runner and use minimum same wire gauge as the two wires, and, of course, do at your own risk!

Attached Images

 

@pavelvoivoda

That is a great recommendation, Pavel. The wires from that plug should be pretty easy to get to, certainly way easier than the relay or fuse.

I am worried about the switch power rating. I suppose if I remember to only run one window at a time this would reduce the amperage but that's not a robust solution.

Perhaps the switch could engage a separate relay that serves to make the 10-3 bridge you are proposing?

I think that the OEM back window lock switch (or any one of the simple push button rectangular switches) used on Gen3 4Runners, that do not have power windows, can handle that power... i think! Contacts seem thicker than the 30 amp fuse's burn point in the casing.

I don't think you'd need a relay. I assume if you open/close all windows at once, it should not draw that much current. But if you have a motor or two that fight against old window seals to raise or lower the glass, then yeah you could get higher amperage draw.

Give it a try, I think that since you are always there when you raise or lower the windows, you will see if the switch that bridges the wires, gets too hot... and you could always say short it intentionally, to see if it will handle 30amps thru and burn the fuse, or if it will spark and melt! haha

If you want to put a relay in the door, here is a edited diagram of the same thing with a relay. It is all doable right there at the door controls bezel

Attached Images

 

Thanks again Pavel! I am thinking about using this nifty "Window Lock" switch from a 1st gen 4Runner:





I'll only use two of the leads. It's a simple push and stay switch (not sure the EE term for that). It's probably 18ga maybe 16ga.

Wondering if maybe I should just wire in a 10A or 15A fuse with this switch just in case.