Another 24v vs 12v question

[akifjanjua]

Hi All,

I am starting the conversion of my BJ40 to BJ44.. hav sourced a donor BJ44 body parts.. now the big question. the BJ40 currently has a 12v electrical system with a 2B engine.. the BJ44 has a 24v electrical system.. i got all electrical body parts 24v.

Now the question.. What should I do?

1. repalce all engine electricals i.e. starter, alternator, glow plugs and EDIC with 24v ones and add another battery

2. Convert the body electricals to 12v.. things to swap would be heater blower, A/C box, bulbs, regulator, glow timer, intrument gauge cluster (i dont knw if these are diff for 24v/12v), relays.. what else?

In my country, the weather is not too cold.. so 12v works all well.. just want avoid the 2 battery cost and the 24-12v conversion issues for powering 12v stearo and 2m radio etc.

Please suggest

regards
Akif Janjua

 

[akifjanjua]

plus with 24v i would need to visit the truck/bus shops for electrical parts like bulbs relays ..

 

[AJAEbj42]

Generally speaking, it's easier to change the engine stuff than the truck stuff if that helps.

But if you have both trucks, then you should be able to pick either option as the parts will be similar between a BJ40 and 44 (gauge clusters, lights, etc.). You don't have to buy all 12V electrical or 24V electrical, just need to go through the effort of exchanging them.

So if you prefer 12V, go with 12V. Just my $.02.

 

[Dieseler]

Go with the 12v swapout..... box up all the 24v stuff and send it to me I will pay for the postage stamp.
Are you planning on stretching out the frame if you measure the bodies up you will find a measurement difference between the door and the front of the rear wheel cutout as well the rear frame is further back plus 44 rear axle placement is further back than the 40...good luck with the swap be sure to take lots of pics and post them.
I can give you measurements if needed.

 

[akifjanjua]

@Dieseler

Yes, we would be stretching the 40's frame by about 14 inches at the rear.. relaocate the rear spring shakles to fit a MWB leaf spring that takes care of the added wheel base.. the body tub is of a donor BJ46 so would fit bolt on will trade the 24v stuff with 12v

if you are really looking for 24v stuff.. there is alot available in my country.. shipping cost is another story

 

[akifjanjua]

whats the difference between the 24v and 12v meter gauges ??

 

[Dieseler]

What country.
If you look at the back of the two gauges 12v and 24v you will see they are different I am not sure what they call them resistors of capacitors but they is a difference I think the wiring plugs are also somewhat different if you try connecting a 24v to a 12v system your gauges will not function properly and if you hook up 12v to a 24v system you will fry all the gauges just like running a 12v radio on a 24v circuit...been there a couple of times where things starting going up in smoke now I have learned my leason and keep everything volt specific.

 

[bj40green]

combination meter / cluster 12 V vs 24V

whats the difference between the 24v and 12v meter gauges ??

The clusters are the same. Both are 12 Volt but...... the 24 V version has a resistor (they call it a dropper) to bring the voltage down to 12 Volts.

You need to swap all the bulbs (5x) to 12 Volt bulbs.
So if you want to use the 24 Version for your 12V set up, remove the resistor and replace it by a jump wire and change all the bulbs and you are good to go. Did this swap myself. Easy to do.

Good luck

Rudi

 

[lostmarbles]

The clusters are the same. Both are 12 Volt but...... the 24 V version has a resistor (they call it a dropper) to bring the voltage down to 12 Volts.
View attachment 502903
You need to swap all the bulbs (5x) to 12 Volt bulbs.
So if you want to use the 24 Version for your 12V set up, remove the resistor and replace it by a jump wire and change all the bulbs and you are good to go. Did this swap myself. Easy to do.

Good luck

Rudi

That FSM you've got there has amazing stuff that no other FSM seems to have Rudi. Thanks for sharing more of it here.

I've immediately saved that pic ...

You did that swap yourself and you didn't have any problem with your "oil receiver/gauge"?

I'm puzzled because the EPC gives a different part number between 12V and 24V oil receivers/gauges (while it gives the same part numbers for the other 3 gauges/receivers.)




PS. I believe the 12V and 24V connection points (to the dropper resister) are actually connected together within the printed circuit board for the 12V combination meter (but obviously not for the 24V version). So I think this would make it even more difficult to do the reverse job of adapting a 12V combination meter for a 24V cruiser.

PPS. On a 24V combination meter the dropper resistor feeds 12V to the fuel and temperature receivers but the oil receiver still gets 24V.

Edit: Actually I should have said that the temperature gauge gets 7V (rather than 12V) because it is of course fed this reduced voltage from the fuel gauge. And this topic is very interesting to me. It proves that the temperature and fuel gauge sender units are identical between 12V and 24V cruisers while the oil pressure sender is different. (And I've just checked the EPC to confirm this.)

 

[akifjanjua]

Rudi you are absolutely correct.. image saved you have hands on a gem of an FSM.. will need your help in future

Here is the pic of the 24v BJ46 gauge cluster... notice the white resistor.. thats the only difference

Also checkout the 24V Radio we got

 

[akifjanjua]

@Dieseler

I am from Pakistan..

 

[Dieseler]

bj40green thank you for that diagram I have never come across one before now I can add it to my folder of diagrams.
Can the dropper be purchase seperate from Toyota since I have several 12v version clusters but all my cruisers are 24v

 

[akifjanjua]

The dropper is a simple high wattage resistor.. i'll check the value of the resistor..

 

[bj40green]

Hello to everybody,

I swapped clusters from 24V trucks to 12V trucks several times.
Just replace the resistor for a wire and change bulbs.
In this case all the senders (oil, fuel, temp) stay the same.
The oil- and fuel meters get a direct 12V and the fuel meter acts as a kind of a voltage regulator and creates a 7V for the temp meter. Funny construction Toyota! Anyway, "Lostmarbels" is right in saying that only the oil sender is different for a 24V truck.
The fuel and temp senders are the same for both systems because they are fed through the resistor / fuelmeter combination.

In short if you go from a 24V system to a 12 V system you swap everything but the fuel and temp sender because the are the same in both systems.

Happy driving.....

Rudi

 

[bj40green]

PS. I believe the 12V and 24V connection points (to the dropper resister) are actually connected together within the printed circuit board for the 12V combination meter (but obviously not for the 24V version). So I think this would make it even more difficult to do the reverse job of adapting a 12V combination meter for a 24V cruiser.

Why???? Cut the print between pin 3 and the fuel meter bolt with a sharp knife, add the resistor, change the bulbs and .................go!

Peace of cake!

Rudi

 

[lostmarbles]

The clusters are the same. Both are 12 Volt but...... the 24 V version has a resistor (they call it a dropper) to bring the voltage down to 12 Volts.
You need to swap all the bulbs (5x) to 12 Volt bulbs.
So if you want to use the 24 Version for your 12V set up, remove the resistor and replace it by a jump wire and change all the bulbs and you are good to go.
Rudi

I don't think you should be saying "the clusters are the same" Rudi. (I find this statement misleading and you even refute it yourself with the conversion steps you have listed here.)

The printed circuit board is the basis of the whole cluster/combination-meter and as I've pointed out, even this appears to be different between 12V and 24V models.

.....
Just replace the resistor for a wire and change bulbs.
In this case all the senders (oil, fuel, temp) stay the same.

Anyway, "Lostmarbels" is right in saying that only the oil sender is different for a 24V truck....Rudi

I'm actually saying that both the oil pressure receiver (ie. the gauge itself) and the oil pressure sender are different between 12V and 24V models.

So I guess you're saying you have found you can get away with running a 12V sender with a 24V receiver? (But if this was an acceptable way to go then surely Toyota would have done it themselves and saved themselves the trouble of making both 12V and 24V units?)

I wonder how long the 12V-24V sender-receiver mismatch (oil pressure) will remain working for and how accurate it is? (But I guess you'll reply that there's no accuracy in those gauges anyway. )

Why??? Cut the print between pin 3 and the fuel meter bolt with a sharp knife, add the resistor, change the bulbs and .................go!

Peace of cake!

Rudi

Ugly but certainly do-able ..... And quite a contrast from the opening statement that the 12V and 24V combination-meters are the same.



PS. I think this thread has cleared up a few things that many of us were uncertain about previously. Anyway that's certainly the case for me..

 

[bj40green]

@ Tom,

About the oil gauge / reading. The needle goes up and down with the rpm's, it's just indicates the pressure, so what if the needle is a little bit off ? Or to say off what? since there is no scale or reference to pressure measurements in lbs or kg's or whatever.

Whith "the clusters are the same" I meant the only difference is the little strip between pin 3 and the fuel meter on the PCB (printed circuit board), and yes such a difference is good for a new partnumber. In the swaps I did it worked beautiful and there is/was no need to change the sender.

Ok, since everybody is happy with my pictures I'll put some more in. In this edition I'll do the fuel and water temp meters.
In the next edition I'll do the oil pressure and amp meter.
Stay tuned.........................

Happy driving,

Rudi

 

[bj40green]

as promised

And here is the 2nd edition of the cluster meters.




I hope I made some people happy,

Rudi

 

[lostmarbles]

Thanks heaps Rudi

By the way, here's a pic that shows everyone that those two terminals are linked by the PCB in the 12V version:



PS. This is a 12V BJ42 combination meter

 

[Dieseler]

Just looking at picture post 10 and noticing the green wire which I would assume is the speed alarm wire anyone have pics of a dismantle of the speedo assembly with that wire or verify that is what it is for.
As soon as the weather improves I have a cluster from a 24v that needs some work on the speedo and have a couple of FJ40 clusters that I could use for parts...so far the post has produced alot of information so that I will be comfortable mix matching from the other clusters if needed.