Please help: switched 12V under the bonnet/hood (1 Viewer)

[stratus]

I have tried the method mentioned here in few threads to take 12V from the main fuse box, but with ignition ON (or OFF) I measure the top openings of the fuses and I don't have 12V there. I have checked them for continuity, they are fine.

Also, there are 4 plugs / connectors which are not connected anywhere - anyone recognize them? 3 of them have 2 wires and 2 with only 1 wire.

The car has 2 batteries, I assume the battery on the left side (where main fuse box is) is the starting battery, right? Well it died, I temporarily replaced it with a old battery which will stay there until I buy a new replacement.

I wish I had a manual for the car, but the online manuals I found so far are for vehciles with 1 battery and petrol V8 engines. Mine is 6 straight diesel with 2 batteries.

 

[Njck22]

So if I understand:

you are looking to get a 12v source under the hood that only comes on when the ignition is on?
If you get no luck finding one, and don’t want to play guess and check you can get the manual and Toyota - tech.eu
Send a picture of the diagram in the lid of the fuse box

 

[hoser]

Your two batteries are in parallel. Those who live in moderate climates will often isolate one of the batteries for use with accessories. Replace them in a matched pair otherwise they'll be short lived.

 

[stratus]

So if I understand:

you are looking to get a 12v source under the hood that only comes on when the ignition is on?
If you get no luck finding one, and don’t want to play guess and check you can get the manual and Toyota - tech.eu
Send a picture of the diagram in the lid of the fuse box

Yes, correct, I need to feed my front camera with 12V only when the ignition is ON.

I have searched in many locations and everywhere I find only the petrol variant with one battery. Will try to search for this tech.eu you mentioned, but I think I was there (will double check) and exceeded my download limit

The lids from main box and a smaller box from the second battery are below.

 

[stratus]

Your two batteries are in parallel. Those who live in moderate climates will often isolate one of the batteries for use with accessories. Replace them in a matched pair otherwise they'll be short lived.

I thought that they are separated, but to my surprise they are indeed in parallel and when one died, both died.

I am planning to buy 2 identical YUASA 5334/5335 batteries, but would consider isolating them if this something not too hard to do. Would appreciate a link to a good DYI on this topic if you know one.

 

[hoser]

There are a lot of ways to wire up a dual battery system. You'll have to choose one based on our budget and needs. Do your research before buying the batteries though.

 

[stratus]

There are a lot of ways to wire up a dual battery system. You'll have to choose one based on our budget and needs. Do your research before buying the batteries though.

the car is my daily driver, so I need to act fast. I will buy Yuasa 5334/5335 pair of batteries to get the car back on the road.

I read some threads on people adding a second battery, but didn't come across yet of a thread where people would separate their dual battery setup. Anyway, after I will learn how to do that, would the above yuasa 5334 and 5335 be a suitable candidates for the conversion, right?

 

[stratus]

can anyone please comment on the plugs I am holding in the opening post? What are they and why they are just lying around there disconnected?

 

[hoser]

Cheapest way....

Better but more expensive way...

Blog | REDARC Electronic

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www.redarc.com.au

....and then there are a bunch in between (IBS, Blue Sea, etc).

In most cases you want (1) starting battery (i.e. your Yuasa) and (1) deep cycle/AGM/Lithium battery. You can also use (2) dual purpose, AGM batteries (i.e. Odyssey)

 

[stratus]

Cheapest way....

Better but more expensive way...

Blog | REDARC Electronic

Welcome to the REDARC Blog. Learn more about the most recent developments and compare stories and experiences within the industry.

www.redarc.com.au

....and then there are a bunch in between (IBS, Blue Sea, etc).

In most cases you want (1) starting battery (i.e. your Yuasa) and (1) deep cycle/AGM/Lithium battery. You can also use (2) dual purpose, AGM batteries (i.e. Odyssey)

Thank you! I will have to read into it. Do you know which battery is starting and which is house one on the factory dual setup please?

 

[hoser]

The starting battery will be directly attached to this:

 

[stratus]

The starting battery will be directly attached to this: View attachment 2138813

Thank you!

 

[stratus]

after reading about the options on dual battery setups, I think I will stay stock, i.e. with 2 batteries in parallel. I am not running any fridges from it, but I have an audio amp and a 1 farad capacitor in my audio setup. There were no problems with batteries until the car stayed for 3 weeks parked. Usually it runs everyday, so I will probably be OK with just 2 yuasa 5334 and 5335..

However, my question on where to get switched 12V remains. So I need to disassemble somehow the big fuse box under the bonnet where all the relays are? Sorry to ask (perhaps obvious to majority) these questions, but I would rather go on a tested path

 

[Colinz]

WRT to the HDJ100 dual batteries, apparently the Jap imports use a funky 24V start system that puts the batteries in series for starting, and then switches them to parallel for 12V operation of the truck, so I'd be very careful about splitting a factory dual battery setup in a diesel 100 series.

If you're not getting any voltage readings from the test points on the top of the fuses, it's likely that your multimeter has probe tips that are too thick to actually make contact with the conductive material. Also, if you're measuring voltage across the fuse, and the fuse is good, then you'll get 0V ignition on or off. You need to measure between the chassis and the fuse.

 

[hoser]

@Colinz I believe the funky 24/12v system doesn’t apply to the 100 series 1HD-FTE, all markets.

 

[stratus]

I will try some needle-pointed probes, thank you for the tip.

On the voltage measurements, I will use chassis (is negative battery post good for this?), but I was hoping to get here some advice on which wire is a tried and proven to work for feeding the camera (and which I should not even touch as not to introduce some noise into some components?)...
I have the gut feeling that there are wires/areas I better not mess with, while others are not that sensitive even if a novice like me works there...not sure if I make any sense here

 

[stratus]

If you're not getting any voltage readings from the test points on the top of the fuses, it's likely that your multimeter has probe tips that are too thick to actually make contact with the conductive material. Also, if you're measuring voltage across the fuse, and the fuse is good, then you'll get 0V ignition on or off. You need to measure between the chassis and the fuse.

OK, I have done that. More problems I am afraid. On the most forward row of fuses (closer to the headlights of the car, the bottom in my pic) I have 12V even after the car has been in the garage untouched for the night! The keys where in the ignition in OFF position the whole time.

First 4 fuses left to right (Radio, Haz-TRN, AM2, Tel - what is AM2 by the way?) had 12V in the morning, however the 4 next fuses (with word "HEAD" in front) had 0V even with ignition ON! Are these fuses for the headlights??

I now removed the keys, locked all doors and set the alarm for the next night measurements.

Anyway, if/when I find the switched 12V fuse, do I have to take the fuse box out and connect to some wires underneath the fusebox which will be exposed? I never took a fusebox out, is there a good writeup (preferably with pics ot video) on this topic?

 

[stratus]

could it be that the switching is done inside the car (since this is where the ignition is)? And every 12V wire under the bonnet will have 12V permanently?.. Anyone?

 

[stratus]

UPDATE:

spent the whole day in the garage with the DMM, it turns out, those 4 most right fuses from the bottom row in my pic, with the word "HEAD" are also live, but they are fused on negative wire!!!

Is this normal or should I be worried?

 

[stratus]

my mysteries go on:

I found a relay, which was put there by the previous owner - it looks nothing like the stock toyota ones.

Here it is the exact model datasheet: https://www.tme.eu/Document/cbb879783f61f23e95b5f334a949d5e9/LDN_SERIES.pdf

It has 5 pins, but only external 4 are wired. The power from battery comes to Pin 87, then pin 87 and 86 are connected between them with a short wire. Wire from 85 goes towards inside of the car. There is continuity between negative battery pole and pin 30, also between - batt pole and pin 87a (the inside one, without any wires attached to it.

Why I am writing about that? I was hoping that this relay will give me a switched 12V (right, that what a relay very often is for?), but no: there is 12V on the pins 87, 86, 85 in any ignition position. Can a relay fail in this way? Can someone with understanding of how relay work, help me understand this setup, so then I can hopefully see if this relay failed in a closed position?