Tachometer not working

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A

Atthruhiker

10 Year
Joined
Jan 27, 2014
Threads
16
Messages
42
Location
Bozeman, MT
Could someone please help me troubleshoot why my tachometer is not working? It just sits at 0 all the time. Everything else on the instrument panel works.

I am new to all this, so what would be your first step in figuring this out?
 
This is for a 1982 FJ60?

Do the other gauges (oil pressure, temp, speedometer) in the instrument cluster function correctly?
If not, check/replace the 5A 'Gauge' fuse at the main fuse box (see attached section of USA FJ60 wiring diagram from the 1980 Chassis Body FSM).

If so, the problem likely lies in a poor signal being sent from the coil (see attached section of USA FJ60 wiring diagram from the 1980 Chassis Body FSM) or in the gauge itself.

You might start by checking to make sure that the green wire connector at the coil is fastened correctly...

Gauge Circuit Wire Diagram FJ60_1980 Chassis Body FSM.webp


Tach and Emission Cont Circuit from chassis-body-1980 repair manual.webp
 
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Cable ? The tach uses an electrical reference from the (-) side of the ign. coil . The Tach needs 3 things to work
1) 12 vdc +
2) 12 vdc-
3) signal reference from the (-) Side of the ignition coil
 
Atthruhiker said:
Could someone please help me troubleshoot why my tachometer is not working? It just sits at 0 all the time. Everything else on the instrument panel works.

I am new to all this, so what would be your first step in figuring this out?
Click to expand...
Did you ever get this problem solved?
 
Slow Left said:
Did you ever get this problem solved?
Click to expand...

No I have not. I checked the green wire at the coil, it looked fine but I went ahead and took it off and cleaned it. I also checked the emissions "computer" and that looked fine too. I also checked the tach itself and also looked fine. I am a little bit suspicious that it might be related to some other electrical problem I have.
Sometimes the volt meter on the dash will read low (below 12V) when trying to start the car and I have to rev the engine like crazy to keep it from turning off. After a few seconds of this the volt meter will suddenly jump up to 14. Other times, weird things will happen like the seat belt light will turn on randomly while driving. The car has also stalled a few times coming to a stop.
 
Which type of alternator do you have: the Tirrill type regulator (the regulator is external and separate from the alternator itself) or the IC type regulator (the regulator is the square box on top of the alternator).

See images below.

Also attached is the part of the wiring diagram for the USA FJ60 from the 1980 Chassis_Body FSM.

Charging System FJ USA Tirrill Regulator.webp


Charging System FJ60 IC Regulator_arrow.webp


Wiring Diagram_FJ60 USA_1 1980 chassis-body FSM .webp
 
alternator.webp
There is my alternator, I believe that is internal. Original one from 1982. I had a suspicion that the voltage regulator might be going bad.
Also, one more thing to ad, Im not sure if this has any relevance but a while back I discovered that the RED wire on the fusible link was bad. I have since replaced it but before that, my car ran very poorly. Battery always died, stalled all the time things like that.

After replacing the fusible link, the car runs perfectly most of the time. (Besides the problems I mentioned above) It will act up occasionally and stall every once in a while or not start.
 
Atthruhiker said:
View attachment 1007016
There is my alternator, I believe that is internal. Original one from 1982. I had a suspicion that the voltage regulator might be going bad.
Also, one more thing to ad, Im not sure if this has any relevance but a while back I discovered that the RED wire on the fusible link was bad. I have since replaced it but before that, my car ran very poorly. Battery always died, stalled all the time things like that.

After replacing the fusible link, the car runs perfectly most of the time. (Besides the problems I mentioned above) It will act up occasionally and stall every once in a while or not start.
Click to expand...

The alternator circuit runs off that RED fusible link (see wiring diagram posted in post #11 above), so if that fusible link went bad or blew it could have been caused by or the cause of additional problems in the charging system.

Are you familiar with taking electrical measurements? Do you have a mulit-meter for taking electrical measurements?

see page 9-11 on in the the Charging System chapter of the 1980 2F Motor FSM for On-Vehicle Inspection for the IC type Regulator.

You can download the FSM here:
https://forum.ih8mud.com/threads/fsms.743084/

Circuit diagram for the IC type alternator on the FJ60 (from page 9-3 in the Charging System chapter of the 1980 2F Motor FSM):

Charging System Wiring Diagram FJ60 IC Regulator.webp
 
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Thank you for your help. I do not have a multimeter unfortunately. I took the alternator off the engine and brought it to the auto parts store. They told me it was fine. I do not know if they checked the regulator.
So are you saying that if the voltage regulator is bad, then the RED fusible link wire will blow?
What other things could cause that red wire to blow?
 
Atthruhiker said:
Thank you for your help. I do not have a multimeter unfortunately. I took the alternator off the engine and brought it to the auto parts store. They told me it was fine. I do not know if they checked the regulator.
So are you saying that if the voltage regulator is bad, then the RED fusible link wire will blow?
What other things could cause that red wire to blow?
Click to expand...
Hmmm...any way you could team up locally with another MUDer who is familiar with doing electrical testing procedures outlined in the FSM? And has a multi-meter?
The procedures is well outlined in the FSM, but it's often helpful to have a co-conspirator on site when building an intuition around electrical circuits for the first time...

https://forum.ih8mud.com/forums/mt-big-sky-cruisers.276/

I can't tell you for certain that the voltage regulator caused or is the likely cause for the failure of that fusible link, but it is on the same circuit, so I would definitely take that into account when approaching the trouble shooting...

The fusible link is a fuse, built to protect a circuit, so any surge in current above it's rated value will cause it to 'blow'. When it blows, it creates a gap in the circuit, preventing further flow of current through that circuit (until it is repaired). This is how it protects the circuit, because if there is a problem with, for instance a spike in voltage allowed to be seen by the battery (one of the primary functions of the alternator is to charge the battery, but it does so at a constant voltage regulated by the voltage regulator), the voltage regulator will allow a current in excess of it's expected value to flow to the battery (if V (Voltage) goes up with R (Resistance) remaining constant, then I (Current) increases proportionally with Voltages...for a DC (Direct Current) circuit...as explained by Ohm's Law where V = I x R). When the voltage regulator makes this error and allows excess current to flow to the battery, it's path is through the Red fusible link. If that current is in excess of the threshold of the fuse, it will cause the fuse to 'blow'.
On the other hand, if the Red fusible link breaks on it's own (old age finally got it, or a mechanic with superhuman strength accidentally breaks the connection) then the path for charging the battery from the alternator is now broken and all that charge being generated by the alternator might try to find another path to ground (but if I really study the diagram, I think there is a diode in there that will prevent that excess current from flowing back through the system in another direction).

Those are two scenarios I might keep in mind when building an intuition during trouble shooting...
 
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Beno lists the part number for the IC voltage regulator as follows (see post #8 in the thread linked below):

27700-38100-84: this is the one bolted to the alternator itself.

https://forum.ih8mud.com/threads/voltage-regulator.791031/

I just did a quick Google search using that part number, and the Toyota Overstock site has it listed as less than US$40...

You might call your local Toyota dealership to see what their price is (or contact @beno here on MUD).

Also, if you use that Toyota part number and cross reference it at your local auto parts store, they might carry it too...

This will give you the cost of the 'trial and error' approach...
 
Thank you Slow Left, you have been incredibly helpful. I went ahead and removed the voltage meter just to see what it looks like. I was surprised how small and simple it is, how could it malfunction? Ill probably just buy another one and if that doesn't work I will give up and go to a mechanic. I have a good friend who is a mechanic so I know he wont cheat me, or overcharge me.
If it was any other car I wouldn't care and I would just drive it as is, but because its my landcruiser I am incredibly picky and want everything to work like its supposed to.
 
Atthruhiker said:
I went ahead and removed the voltage meter just to see what it looks like. I was surprised how small and simple it is, how could it malfunction?
Click to expand...
They are very innocuous looking...but serve a purpose beyond their size and simplicity in appearance (as is often the case with things of real value)...

Atthruhiker said:
Ill probably just buy another one and if that doesn't work I will give up and go to a mechanic. I have a good friend who is a mechanic so I know he wont cheat me, or overcharge me.
Click to expand...
Hmm...on a philosophical note, sometimes identifying the problem (troubleshooting) is the hard part...and once you know what to do, turning the wrench it doable...

In this case, the troubleshooting happens to be electrical...so if that is a new angle on wrenching, then you're fortunate to have MUD and would even increase in fortune if you've got a local MUD co-conspirator...

Atthruhiker said:
If it was any other car I wouldn't care and I would just drive it as is, but because its my landcruiser I am incredibly picky and want everything to work like its supposed to.
Click to expand...
Understood.
 
Here are some common symbols for components in a DC (Direct Current) circuit...written in 'Toyota', nonetheless...

Toyota Wiring Diagram Symbols.webp
 
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