Clusters, Gauges, Speedo & Odo meters (1 Viewer)

[bj40green]

View attachment 1818567 After buying a new speedo cluster I still had low readings of fuel and temperature, I tested the voltage at the tank with a 3watt lamp as suggested. The lamp flickered quickly not the clean on/ off pulses it should be, 1 second on one second off.
This on /off pulse gives the 7 volt discussed, that is 14v (nominal) on /off at a 50% duty cycle giving the AVERAGE of 7 volts.
I took the challenge and installed the electronic voltage regulator as discussed earlier in this post.
Now I have a steady 8 volts ( only 7808 voltage regulator available, 78 is the series and the 08 indicates the voltage output ) wow both displays steady and indicating what I feel to be correct values.
See photos re installation
Photos out of order, sorry.
First shows how I cut the thick wire from the mechanical voltage regulator to the centre connector of the fuel gauge, also the thin wire was unsoldered from the centre connector.
Second photo shows the original Toyota setup in the fuel gauge.
Last photo shows how I mounted the 7808 voltage regulator, a M3 hole was drilled and tapped, M3 screw attaches the regulator to the cluster without any insulation ( the mounting tab is at negative voltage, the top wire goes to 12v, the centre wire goes to negative( to make sure of a reliable negative connection) the bottom wire goes to the connection between fuel and temp gauges supplying the 8 volts.
It works,
Post if you want more details.
The white mess is a NON corrosive adhesive

View attachment 1818565 View attachment 1818566

Nice job. If you want the voltage a bit lower, you can put a diode in series. A diode drops the voltage by 0.6V so you'll get 7.2 Volt.

Rudi

 

[ToyotaMatt]

Yes, 2nd Excellent Job

 

[rstoddard]

Hi Eric,

Those readings doesn't look good, I'm sorry to say.
It looks like you have 2 problems.
The first one is the OIL circuit and the second one is the Voltage Regulator from the FUEL gauge that isn't working.

Pin2 = to OIL sender and should read 5V. You say 12V which means that the gauge is OK but the circuit is open.
Possibilities are: broken wire to sender, sender not connected, faulty sender.

Pin4 = to FUEL sender and should read +/- 6V intermittent. You say no reading which means that the internal Voltge Regulator inside the FUEL gauge is defective.

Pin5 = to TEMP sender. Here we have 2 options why it doesn't works but because this gauge is fed from the FUEL Voltage Regulator we save this one for later.

I don't know your electrical skills and ability to work with really tiny parts and a solder iron but if you want we can dive deeper into that Fuel gauge and see what is defective.

For the FUEL gauge; The easy way to fix this is get another one.
Another option is to buy an external FUEL meter and sender for under the dash.
Third option is to replace the mechanical VR for an electronic (LM7807) VR. The costs are less than 1$ but you need some skills to modify the Fuel gauge for this.
For the OIL gauge you have to trace where the problem is. The wiring or the sender.

Hope this helps a bit,

Rudi

Rudi, is there a diagram or drawing that shows how to make a 3.4 test light like this?

 

[bj40green]

You can use a test light like this

 

[ToyotaMatt]

You can use a test light like this
View attachment 1827118 View attachment 1827119

1995 era Snap-On Test light w/ updated upgraded Green LED bulb

 

[bj40green]

Th led doesn't draw enough current (i think) for this specific test. Did you test it?

Rudi

 

[ToyotaMatt]

Th led doesn't draw enough current (i think) for this specific test. Did you test it?

Rudi

i have not used a LED bulb in this specific FSM field test application



since a LED bulb has little to no resistance , it sounds like it might affect the test results possibly as u suggest ?



good call

 

[bj40green]

Hmmmm, on the FUEL and TEMP test the 3Watt bulb replaces the sender. In other words it is a load.
On the OIL test I'm not sure so it's worth to figure that out.

Rudi

 

[secondharmonic]

Rudi et. al,

I have been following this thread for quite a while and want to thank you and others for your persistence on not only tracking down elusive information but also experimenting and publishing new information.

There are three cluster-related issues I've been dealing with. My rig is a 1979 BJ-40, Gen 4 24V Cluster, imported to the US from Canada. Cluster modified by PO from Km/h to Mi/h at some unknown date.

Issue 1: This is my biggest issue. AMPS. +/- 50A scale reading zero with no perceptible movement even when energizing glow plugs. I will attempt the "18 inch fusible link" modification that others have proposed in this thread and report back.

Issue 2: Oil pressure reading appeared very low. I replaced the oil pressure sender and now appears normal (as normal as can be expected given the oddly calibrated pressure gauge scale).

Issue 3: Speedometer consistently reading 5 MPH low. Note this is a constant 5 MPH offset regardless of speed (verified by GPS), not a proportional error (i.e. not "10% low"). I am less worried about this as I have a B engine and can roughly gauge my speed by the velocity of cars passing me, but would love to hear potential fixes by anyone who has seen this problem.

Thank you all for the work you have done and look forward to contributing to this thread. I'll write back after I tackle the ammeter issue.

 

[bj40green]

Hi Buddy,

#1: Go for it. It will solve your problem.
Note: The Ammeter doesn't show the current for glowing.

#2: Problem solved.

#3: This can be related to tire size. search for: Speedo Gear.

Rudi

 

[secondharmonic]

Rudi,

#1: Concerning ammeter: Great tip, thanks. I now see there are multiple fusible links on this rig, and only one of them informs the ammeter. The glow plugs are on a different path.

#3: Concerning speedometer error: I do not believe the problem is due to a tire size / speedometer gear ratio mismatch. I am seeing a constant 5 MPH error (at a true 10MPH it reads 15, and at a true 50MPH it reads 55). If it were a gearing problem, the absolute MPH error would grow at higher speeds. It's as if the needle is assembled incorrectly and simply points to the wrong number. I am hoping there may be some tuning that can be done to the speedo to fix this constant offset without needing to tear apart the entire delicate mechanism.

Thanks again!

 

[bj40green]

I am hoping there may be some tuning that can be done to the speedo to fix this constant offset without needing to tear apart the entire delicate mechanism.

Take of the front of the cluster. Pull the needle and replace the needle a bit below 0.

Rudi

 

[secondharmonic]

Take of the front of the cluster. Pull the needle and replace the needle a bit below 0.

Rudi

Got it. Thank you for the advice; I will report back on the ammeter fix and the speedo fix.

 

[nateclowar]

I saw on Page 7 of this thread (post#130) Rudi bridged some connections on the PCB and I am hoping to do the same.

I have a 1978 FJ40, and my fuel gauge stopped working. I tested the sender since I had recently changed the gas tank a few weeks earlier, and it tested out ok. The fuse tested ok as well. Looked at the instrument cluster from below, and I saw a fist sized mud dauber nest that had fallen on the barrel connector and was sort of wedged there. When I pulled the cluster out and took the barrel connector off, I saw the PO had soldered a bit on some of the copper tracks. Unfortunately, it bent and fell away as the connector came off. Guessing the impact may have loosened the previous fix?

The picture shows the left side you can see the damage, right side is where I believe I need to solder a wire between. Without the ground the fuel and lights are out. The AMP still works and OIL/TEMP had been moved to aftermarket gauges by the PO.

I haven't soldered anything on a board since high school. Any tips? Instructions or links for a complete novice? What should I do to prep, gauge of wire? Etc?

Thanks!

-nate

 

[bj40green]

The circuit board is protected by a blue film. You have to scratch that off a bit to make space for your solder point,
I use a fiber glass pencil.

Rudi

 

[nateclowar]

I tried bridging, and it did not work. Maybe I've connected between the wrong points? Right side blinker works, no left side, no other lights, no fuel gauge. (Other two gauges go to aftermarket cluster by PO and never worked) Any ideas what I've done wrong, or next steps?

I've read about the 3.4w bulb test, but can only test using the battery. I need to re-read, but I didn't understand there could be an issue using the battery directly? Would I need to use an inline 15A fuse like heater one?

 

[secondharmonic]

Rudi et. al,

I have been following this thread for quite a while and want to thank you and others for your persistence on not only tracking down elusive information but also experimenting and publishing new information.

There are three cluster-related issues I've been dealing with. My rig is a 1979 BJ-40, Gen 4 24V Cluster, imported to the US from Canada. Cluster modified by PO from Km/h to Mi/h at some unknown date.

Issue 1: This is my biggest issue. AMPS. +/- 50A scale reading zero with no perceptible movement even when energizing glow plugs. I will attempt the "18 inch fusible link" modification that others have proposed in this thread and report back.

Issue 2: Oil pressure reading appeared very low. I replaced the oil pressure sender and now appears normal (as normal as can be expected given the oddly calibrated pressure gauge scale).

Issue 3: Speedometer consistently reading 5 MPH low. Note this is a constant 5 MPH offset regardless of speed (verified by GPS), not a proportional error (i.e. not "10% low"). I am less worried about this as I have a B engine and can roughly gauge my speed by the velocity of cars passing me, but would love to hear potential fixes by anyone who has seen this problem.

Thank you all for the work you have done and look forward to contributing to this thread. I'll write back after I tackle the ammeter issue.

I finally got around to working on the Amp meter. As you guessed Rudi, the "adding a long length of fusible link" worked and the gauge is now functional. A few observations and thoughts:

1. The image below shows the maximum needle movement I'm now seeing (top image is engine off with all accessories/lights on (discharging). bottom image is engine on (charging). So the gauge clearly works. It appears that a +/- 50A scale is just too large for what is needed for most normal purposes. Especially on a 24 V vehicle where the consumed currents are lower than a 12V vehicle.

2. I used 2.3 feet of 14 GA fusible link. I believe 18 inches was mentioned earlier in this thread, but the resistance I've seen quoted for 14GA wire is 2.5 ohms/1000ft. Thus requiring 2.3 feet to achieve 0.006 ohms. Does anyone know where the original estimate of 18" came from?

3. Both of the 5A fuses in-line with the ammeter were blown somehow, so make sure to check them if you do this modification. I don't understand how they both could have blown, but all is good now.

Thanks everyone for the great work on this thread.

 

[bj40green]

Good job @secondharmonic
The 50-0-50 Ammeter was designed for 12V Cruisers so in a 24V Cruiser it shows half the Amps.
The set up was designed by member @amaurer with the help of @lostmarbles You can find it here: Clusters, Gauges, Speedo & Odo meters posting #85.
Unfortunately a lot of pictures are removed from Photobucket since they want money for it .
The 5Amp fuse(s) blows when the fusible link burns up. It's a protection to prevent that the full current goes through the Ammeter.

Rudi

 

[hey you]

Good Morning,
Excellent tech! Will a third generation gauge ( fuel and temp) fit into a second generation cluster? I have a temp gauge thats no longer working and have found a couple third generation gauges that are working.

 

[bj40green]

It's doable but you have to make some modifications.
First: Gauges and senders are a set! You can't mix up 2nd and 3rd gen. gauges and senders.
You have a 3rd gen. FUEL and TEMP gauge.
They work different from the 2nd gen. In the 2nd gen cluster each gauge get's 12V and is hooked up to its sender.
In the 3rd gen. the FUEL and TEMP gauge are a combination. The FUEL gauge has a built in Voltage Regulator that feeds itself and the TEMP gauge. That's why the FUEL gauge has 3 studs. You'll find the explanation in this thread.
Next: You have to change the TEMP sender and will need an adapter to make it fit.
Next: You have to change the FUEL sender and have to modify the mounting.
In short: It's doable but I think that you're better of by placing an ad for 2nd gen gauges in the classified section or go for a Dakota cluster.

Rudi