Clusters, Gauges, Speedo & Odo meters (5 Viewers)

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The amp meter in my 40 (80 production date) has two fuses built into the harness and are shown on the OEM wiring schematic. They're wrapped with Toyota yellow electrical tape near the charcoal canister under the hood where the harness pokes through the firewall.

There's a thread somewhere about how the 50 amp meter was never really functional since the shunt was not designed correctly. In that thread the author looped some 14 ga. fusible link "wire" and fiddled with the length to get the correct resistance and was able to get his 50amp meter to work. May be worth a bit of work with the search function. It seems a lot of the work may already have been done.

Good luck and keep us posted.
 
Sorry Matt;
I'll have to disagree with this one.
This is inaccurate and scaremonger.
Maybe you didn't have time to read the post?
He asks why you can't add an external shunt to the 50A meter to make it perform as the 30A meter does.

The 50A gauge is a Volt meter as 4x4SW clearly understands, but is not a 12V meter as you state. If full scale deflection was at 12V, then you'd be dropping 12V across the remote shunt, leaving zero volts for your truck which is clearly not the case.
FSD is actually few milli-Volts, and the actuall value should be determined by testing it. This is why they die when 12V is applied across it.

The correct answer is that there's NO REASON why you can't do this, however you do need to be a little careful on a few points.
Firstly, you need to correctly size the shunt for the meter. Test the meter to see what voltage is needed to achieve full scale deflection, and then use that voltage divided by 50A to find the shunt resistance.
Secondly you need to make sure that the shunt is properly insulated to avoid a risk of shorts (note that the original design leaves the screw terminals uninsulated and very close to the grounded metal surround, so you don't need to go crazy, just be sensible, and check that you have a fusible link). Remember that over-insulating wires actually has the negative effect of derating them due to their inability to lose heat.
Finally, you might consider adding a small fuse between each side of the meter and the shunt - this avoids any possibility of dumping 50A onto the PCB.
Alternatively, or additionally, you could do this using an inline resistor of around 1K on both sides.

Good luck with this - I think there are quite a few people who might appreciate this type of solution.

Search for current sense resistors on somewhere like Mouser to get a full range of values.
Thanks. I agree the importance of making sure the shunt is protected from grounding out! I was thinking a fuse on the powered side to the guage but heck why not both sides for added reassurance (will do). Now if anyone has the brain power/knowledge to advise what is needed. The shunts in my photo I actually purchased and have. 50 amp 50 and a 75. Part of my issue is I just guessed thinking since the guage was 50 i should get a 50 amp shunt and then there were options on the mv??? I completely and openly admit I do not yet understand the mv…

'
i was not intentionally using any form scaremongery.

my eyes focused in his words i quote in yellow below ,...

, cannot just be installed behind the cluster reconnecting the existing large white wires

when city racer first came on the scene and had the updated YAZAKI 83100-60180 cluster meter offered in his then shutter bug store , i suddenly became a un-affiliated , next needed parts step , as folks needed the 3pin connector for the HBI and the stand alone dedicated ground circuit too , also tons of older pre-72 era cluster trucks needed my recently reproduced 12 pin YAZAKI barrel connector kit too ....


- during that early time period to present day , i have crossed paths , mostly by folks whom PM< me here on MUD and now Igram too , that they flipped up the cluster to install it and it blows up and catches fire , or they then re-hook-up the battery cable and see smoke start to rise from behind the hood , and out the windows in the cab .......


- so , my only intent was to help here and prevent what i have seen TONS of photos or , and folks mailed me the clusters to repair initially ,

only good remaining parts inside is the GLASS pane gauge windows


thanks for clarifying the bigger picture here , :)


matt
 
Thanks. I agree the importance of making sure the shunt is protected from grounding out! I was thinking a fuse on the powered side to the guage but heck why not both sides for added reassurance (will do). Now if anyone has the brain power/knowledge to advise what is needed. The shunts in my photo I actually purchased and have. 50 amp 50 and a 75. Part of my issue is I just guessed thinking since the guage was 50 i should get a 50 amp shunt and then there were options on the mv??? I completely and openly admit I do not yet understand the mv…
What I think I know….. I think the mv will be divided into the 50 amp so I think the 75mv will put less amps to the guage vs my 50mv (total guess based off of reading). Any help from a guru is appreciated!
Well if you have them already then you can start by measuring the resistance of them with a meter set to Ohms.
My 50A gauge was fried when it arrived, but I managed to put some volts across it today, and I'm actually measuring about 2V at full scale - it is pretty trashed though so not sure I trust this.
2V / 50A = 0.04 Ohms
If your shunt resistance is larger than this, then you'll get a bigger voltage drop across it; you will fry the gauge and you might also have ignition problems due to the lower line voltage, so avoid that.
If your shunt is lower resistance then it will work fine, but the gauge just won't move so far.

Yes, put s fuse on both sides - either could provide 50A+ in a fault condition.

If you're not at all sure about anything, then best not to do it though of course :)
Oh I clearly am not sure about anything but here goes. 50 amp 75mv shunt is installed now. I tried to check ohm while unhooked but i get basically open or closed on any setting i try. Voltage is about the only luck i have with my tester thus far which is obviously going to check out. The
 
I struggled getting anything useful out of my multimeter in regards to testing. I think it's too low to read with my cheap meter or operator error. The 50 amp 75 mv shunt was 8.99 for 2 on amazon. My FJ40 is a 76 so it did not have the amp plug it had the two white wires that went on the posts. This allowed them to hook directly to the shunt on the larger posts. I do not notice any issues with starting up which is obviously the largest amp draw. I plan to run everything along the shunt in and out the same side allowing me to slide a large heat shrink tube over it. I will then secure it so that it is not rubbing behind the cluster. I recognize this is not the best option. I agree getting it out of the dash would be the best solution, but I am ok with it. Next, I made three 12 gauge leads that are about 16” long and heat shrunk fuse holders on each one running to the gauge. The 3rd is a ground for the high beam. I do not have a plug, so I used shrouded female spades to go onto the cluster. I didn't love hooking a hot wire to the - side of the amp guage but after testing it was obviously +12 volts coming out of the other side of the amp gauge as anticipated. I put a 5-amp fuse in each of the fuse holders and ran and took cover….. After 5-10 minutes of no loud explosions, I poked my head out only to find no smoke or flames thus far. The needle naturally completely unhooked slightly reads under zero and that is where it reads when I hooked it up. The lights turning on do not seem to be enough to change it much if at all. When I start it up the needle drops slightly due to draw while cranking and then climbs slightly to the positive side enough to give me the indication that good things are happening. Just know that this is a stretch as you have to be watching the needle and manifesting results in your head lol but it is enough to know that I shouldn't need to rush home before I have a dead battery LOL. Now from what I read the design sucks regardless especially with an internally regulated alternator. I simply wanted to keep the guage. Right now, it barely beats that by a slight margin but enough for me to be happy. It is basically a dummy light at this point. Now hear me out I am not saying this worked!!!!! Tomorrow you may hear of a FJ40 that was really nice but went up in smoke! I am simply reporting back, as promised, on what I know so far.
IMG_6581.jpeg
 
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Sounds like your shunt resistance is too low, and not producing enough voltage across it to move your gauge...

Since you have two shunts just sitting there, you could try wiring them both in series to increase your resistance.
 
Sounds like your shunt resistance is too low, and not producing enough voltage across it to move your gauge...

Since you have two shunts just sitting there, you could try wiring them both in series to increase your resistance.

Sounds like your shunt resistance is too low, and not producing enough voltage across it to move your gauge...

Since you have two shunts just sitting there, you could try wiring them both in series to increase your resistance.
I am not opposed to trying it a well as the 50mv shunt as well to rule some things in or out
 
Anybody find a replacement gauge that fits the OEM location and just measures voltage? I gave up on a shunt and am just measuring voltage for alt/bat health.
 
I'm not aware of a VM that will fit the OEM dash but AutoMeter has a relatively small (think 2.1/8" dia.) VM both analog and digital that you can mount off the side of the steering wheel column cover.
 
The OIL gauge and sender / 12 and 24Volt

As mentioned before in this thread, there are 2 models of OIL gauges and senders. The 12Volt and the 24Volt model (for BJ's only). The difference is the internal resistance for each model.
44Ω for the 12V model and 66Ω for the 24V model.
Of course the senders are different too.
Here is how it works. As we've seen before, the FUEL and TEMP gauges are fed 7Volt by the internal Voltage Regulator from the FUEL gauge.
The OIL gauge works on the same 7Volt principle but now the Voltage Regulator is inside the OIL sender.
The (pressure) membrane is moving the working point from the VR to a higher level.
If there is no pressure the VR is open, the gauge shows Low (= 0 kg/cm² or 0 psi).
If the pressure is low the VR will open after a short time of heating up the bi-metal and the gauge will show at the second mark (= 2kg/cm² or 28.4 psi).
If the pressure is high, the membrane moves the VR (and so the bi-metal) to a higher working point which will result in a longer time (heating up) before the VR opens up. The gauge will show at the third mark (= 4 kg/cm² or 56.8 psi)
The fourth (H) mark = 6 kg/cm² or 85.2 psi.
As you can see in the FSM test procedure (posting #7) the gauge is tested by grounding through a 3.4 Watt light bulb. There is no mentioning of "flashing".
The sender is tested by applying 12Volt to a light bulb which is connected to the sender. The test shows the light bulb "off" when the engine is not running and "flashing" when the engine is running.
View attachment 590724

Rudi
 
Rudi-back on post #28 you say to test the oil pressure sender with a 3.4 watt bulb connected to 12 volts. Is that also true for my 24 volt BJ Canadian spec with 3B diesel?
 
Rudi-back on post #28 you say to test the oil pressure sender with a 3.4 watt bulb connected to 12 volts. Is that also true for my 24 volt BJ Canadian spec with 3B diesel?
Thanks Rudi, however, is it correct to supply 24 volts to the oil sender on a24 volt BJ during testing or is 12 volts acceptable on a 24 volt oil pressure system?
 

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