BJ40 24 volt gauges

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N

NielsC

10 Year
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Jan 26, 2014
Threads
32
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152
Location
Belgium
None of the gauges on my 78 BJ40 work, the senders are there but no wires connected.
I checked the back of the cluster and the wires for the gauges are in the plug but they are simply not connected. Is it simply a matter of connecting these wires to the gauges ?

I also checked the voltage dropper at the back of the cluster, but on either side of the resistor I measure 24 volt. Shouldn't it drop the voltage for the gauges to 12 volt ? If it is supposed to but it doesn't, are the gauges burnt out or not ?
 
Hoi Niels,

Everything about clusters and gauges you can find ->Here.

There is only a voltage drop when everything is connected.

Only the OIL gauge is 24V. The Fuel and Temp gauge are fed by the resistor.

Rudi
 
The gauge side of the resistor should be 12v....if you are getting 24v something is wrong.
I am not sure if you can check them with a 12v jump wire I believe they work off resistance from the sender but I would think if you applied 12v to the gauge the needle would spike to the top .
 
Dieseler said:
The gauge side of the resistor should be 12v....if you are getting 24v something is wrong.
I am not sure if you can check them with a 12v jump wire I believe they work off resistance from the sender but I would think if you applied 12v to the gauge the needle would spike to the top .
Click to expand...

If there is no current draw the voltage is 24V on BOTH sides of the resistor.

If you jump the sender (to ground) the needle will go into the corner and if you do that too long you'll see smoke!

"I'm not sure....." , "I believe....." and "I think...." is a bit risky advice.

Rudi
 
Danku Rudi !
Yeah i should have known that if there is no current draw the output stays the same as input.
Will wire them up tommorow and see if the work.

The wires from the gauge to sender, should i measure 12 volt on those wires ?
 
It's important to understand that a 24V cluster is a 12V cluster with 3 modifications.
1. The voltage for the FUEL and TEMP gauges is lowered from 24V to 12V by a 30 ohm dropper resistor.
2 The OIL gauge is 24V.
3. All light bulbs are 24V.

First: check the value of the dropper resistor. It should be 30 ohms +/- 20%.
If the reading is MUCH more it means it's defective, blocking the current flow.
If it's "OL" (Open Loop) you should not have 24V on the left side.

You can apply 24V to pin 3 (or the right side of the dropper resistor) or you can apply 12V to the left side of the dropper resistor (= left stud FUEL gauge).
May I suggest that you use an in-line fuse for this purpose. I mean you can do some nice welding with a battery.
cluster.webp
At this point the internal VR (Voltage Regulator) inside the FUEL gauge should start working. This VR is a bi-metal that switches the 12V on and off which results in an average 6 to 7Volts. This voltage appears on the top and right stud of the FUEL gauge. If you use a digital volt meter you'll see rolling numbers. If you use an old school analog meter you'll see a wobbly needle around 6 -7 Volts.
Most people don't know how to handle this and that is why the FSM says "dont test this".
Okay. The top stud is the output for the TEMP gauge and the right stud is the same as pin 4 for the FUEL sender.
Pin 5 is for the TEMP sender. So on pin 4 and 5 there should be that wobbly 6 - 7 Volts.
Pin 2 is for the OIL pressure sender (which has an build in VR BTW) and this pin should show the same voltage as what you applied on pin 3, so 12V or 24V.

Rudi
cluster.webp
 
Thanks mate but shipping from the US to Europe is a bit too expensive i guess, not to mention there are alot of second hand toyota parts in Belgium as well :)
 
So i checked the voltage output on pin 4 and 5 and indeed i get something from 3 to 12 volts, it's always changing but seems to settle around 6 volt. I checked with ign turned on and cluster plugged in. So i simply connect the wires to the senders and they should work ?
 
Dropper Resister

Rudi

If the Dropper Resister is brunet, is it possible to replace it with a normal high ampere 30 Ohm Resister from a electronic shop OR a Ceramic type is required ? (for a 24V Cluster)
 
WDT Siri said:
Rudi

If the Dropper Resister is brunet, is it possible to replace it with a normal high ampere 30 Ohm Resister from a electronic shop OR a Ceramic type is required ? (for a 24V Cluster)
Click to expand...

Yes, you need a Ceramic type power resistor.
30 ohm, J = 5% tolerance, 20H = 20Watt, Brand = Micron, model = X
Toyota part #83145-60010 if it is still available, but you can buy them at electronic shops or Ebay as well
83145-60010 dropper.webp


Rudi
83145-60010 dropper.webp
 
fatdiesel said:
...and I would assume that the amps gauge is 12volt as well?
Click to expand...

The Amp gauge is not voltage rated. It measures amperage. It doesn't matter if it's a 12V or 24V or even a 48V circuit is.

Rudi
 
I checked the gauges today as Rudi said, I also followed the manual to use an 3,4 watt test lamp. And I got the gauges working this way. The fuel gauge is connected now but doesn't work, so I think it has a bad ground.
 
NielsC said:
I checked the gauges today as Rudi said, I also followed the manual to use an 3,4 watt test lamp. And I got the gauges working this way. The fuel gauge is connected now but doesn't work, so I think it has a bad ground.
Click to expand...

Or broken wire, or bad connection, or defective sender, or..... always a nice puzzle.
Check the sender with the ohm meter. Should be between 17 and 130 ohms.
If that's okay, continue with the sender wire from barrel connector to sender. Should be 0 ohm.

Rudi
 
Recently I changed Alternator(24V) to a single wire type & now Amp Gauge just lying idle without any connections.

How to convert this as a Volt Meter ? May be +50 end could show 24V.

Thank you in advance.
 
WDT Siri said:
Recently I changed Alternator(24V) to a single wire type & now Amp Gauge just lying idle without any connections.

How to convert this as a Volt Meter ? May be +50 end could show 24V.

Thank you in advance.
Click to expand...

You can not convert an Amp gauge into a Volt meter.
You can install an external Voltmeter like this.
DSC06311.webp

Rudi
DSC06311.webp
 
WDT Siri said:
Recently I changed Alternator(24V) to a single wire type & now Amp Gauge just lying idle without any connections.

How to convert this as a Volt Meter ? May be +50 end could show 24V.

Thank you in advance.
Click to expand...

Here is another option; remove the Ammeter and replace it with a 24V Voltmeter.
For more info look at this thread: https://forum.ih8mud.com/40-55-seri...ven-mechanical-gauges-into-stock-cluster.html

Find a 24V meter, take it apart, make it fit your cluster.
Thanks to Amaurer for the pics.

In this pic the Amp gauge is replaced by a meter for 12V systems.
7.webp

4.webp

5.webp

Rudi
7.webp
4.webp
5.webp
 
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