HZJ75 tacho sender make/model and signal (2 Viewers)

[Richard Luksozek]

I have just completed the 4JJ engine/gbox transplant into my restored 70 series and finishing the off getting the instruments working. Got them all except the tacho BUT need help with details of the sender and/or its signal. What I gather is that the sensor is a Hall Effect transducer and pulses are triggered by a rotating magnet inside the 1HZ injector pump. I am looking for technical data sheet on the sensor or manufacturers make/model etc so I can track down the signal characteristics. I know the tacho reads the incoming digital pulses into its PWM circuit then outputs to the needle coil for revs based on input frequency. That's about everything I can work out without a HZJ75 to look at... Would appreciate your help if you have been down that same path. Cheers Richard

 

[RhinoRig]

Same issue here. Watching and impressed by the diagnosis.

 

[Richard Luksozek]

Another question I need help with. If you have an old dismantled HZJ75 injector pump lying around I would love a photo of the main shaft where the sensor goes. I'm hoping to see how many lobes there are which the tacho sender senses. Some housings only had an undrill recess but I'm hoping all the internals shafts were the same. This will help me understand a bit more how the PWM circuit works in the tacho in the event that I need to design a new solution. X# Pulses in to PWM = X# Vout to rev needle coil. = rev displayed.

 

[Richard Luksozek]

New update. Pump main shaft has a Drive Gear which intern drives a Flyweight holder in the upper section of the pump where the tacho sensor is mounted. All pumps will have these so for those of you wondering if there are any internal differences between pumps with tacho sensor or those with a blank then the answer is none. The tacho sensor seems to pick up on the teeth of the driven flyweight holder and from what I can see there is 32 teeth. Can anyone please confirm this if you have a pump in pieces?

 

[Richard Luksozek]

Just putting out there again if anyone has a HZJ injector pump in bits could you confirm the number of teeth on the Flyweight Holder gear. I have it on very good authority (instrument restorer) that it is probably 24 teeth. He tells me the sensor runs at 600hz (600 pulses/sec) for 3000rpm with makes it 12 teeth per engine revolution. Since the pump runs at half engine revs (4-stroke engine) then it follows there are 24 teeth on the gear. Just another assumption correction, it seems the sensor is not a Hall Affect but a bi-directional induction proximity sensor. Output can still be either digital. or AC. I have ordered a sensor and will give it a test in the coming week. If it works then its a fix for under $20..

 

[Houser]

If the new sensor works but the tach. Reads incorrectly there may be a resistor on the Tach circuit board that can de
changed to correct the error. When I switched to a mechanical injection pump on my lj78 I had to increase the correction resistor value 20Kohms. The resistor position on the circuit board was labeled R-T.
hope this helps.

 

[Richard Luksozek]

More research reveals the Denso/Toyota part numbers are 076300-1240 /83180-32020 and although most suppliers are out of stock, they can be found for about US$77, here is one I have found TOYOTA DETECTOR | 83180-32020 - https://carmarka.com/en/toyota-detector-83180-32020. I have also discovered the sensor has an AC analog output (sine wave) but still haven't found the output voltage range.. Unfortunately that means my $20 fix wont work since this sensor is digital. If anyone has put a CRO on the output signal then would love to see the wave form.

 

[Richard Luksozek]

Some good news based on a bit more testing. Wave form input to the tacho from the sensor is definitely sine wave. The signal is sent to the tacho via the signal cable which also provides the sensor excitation voltage which is supplied from the tacho. AC signal over DC operating volts. So I connected sinewave generator output from my digital CRO to the tacho signal cable and viola... tacho works. What I found is the AC sinewave signal voltage is 2vAC and with frequency set at 500hz the tacho reads 1750rpm. So am now hunting for a 2-wire magnetic Induction proximity sensor that uses DC as its operating volts and produces an AC sinewave signal of about 2vAC. Will keep you posted.

 

[coldtaco]

No idea what your talking about but awesome you can find a solution hopefully

 

[Rigster]

Just a thought, but if you are going through this much effort, would it be easier to find a solution that feeds the tach from the alternator? Many newer vehicles do it this way. I have not looked into that option at all, just spit-balling here.

Hopefully you do not need to crack open the fuel pump is all. Big job...

 

[Richard Luksozek]

No idea what your talking about but awesome you can find a solution hopefully

Thanks for your comments and yes the techno stuff isn't for everyone. Ultimately hope to find a 3rd party universal sender that will plug into the Toyota wiring harness and make work any toyota tacho. There are lots of options how to pulse the sender it access to the gears in the pump aren't available.

 

[Richard Luksozek]

Just a thought, but if you are going through this much effort, would it be easier to find a solution that feeds the tach from the alternator? Many newer vehicles do it this way. I have not looked into that option at all, just spit-balling here.

Hopefully you do not need to crack open the fuel pump is all. Big job...

Yes very true, alternators have been used but for me this is trying to get the simple original HZJ75 dash tacho working over the original wiring harness after a D-Max 4JJ motor transplant. Totally different pump so not planning to look at the pump as an option for the sender. Most alternators have metal cooling fins that may be useful as a pickup for the sender to replace the teeth in the original fuel pump..

 

[John Young]

I'm also someone who would like a tach on every vehicle. I have a 1HZ pickup and a couple of 1FZ 70 series without it, and it annoys me.

Is the point of what you are doing to get a factory tach to work in the dash, or is it to have a tach, because I've considered a couple of times adding a tach in the fuel tank binnacle of the 70 series, but not the factory tach.

 

[Rigster]

Yes very true, alternators have been used but for me this is trying to get the simple original HZJ75 dash tacho working over the original wiring harness after a D-Max 4JJ motor transplant. Totally different pump so not planning to look at the pump as an option for the sender. Most alternators have metal cooling fins that may be useful as a pickup for the sender to replace the teeth in the original fuel pump..

Ah shoot, sorry, I missed that you were swapping it with the 3.0 4jj. Which version?? The turbo TCX?? That would make that cruiser zoom along quite nicely and give you decent fuel economy to boot. (When compared to the stock 1HZ)

Best of luck getting a proper current signal to the stock tachometer. I am sure with enough patience you will get it working!

 

[Richard Luksozek]

Ah shoot, sorry, I missed that you were swapping it with the 3.0 4jj. Which version?? The turbo TCX?? That would make that cruiser zoom along quite nicely and give you decent fuel economy to boot. (When compared to the stock 1HZ)

Best of luck getting a proper current signal to the stock tachometer. I am sure with enough patience you will get it working!

No worries, I don't think I mentioned the 4JJ conversion, was more focused on the tacho. Engine (4JJ1), harness, ECU, 5spd G/box all out of a 2012 ute.. Designed a new stub shaft and 25mm Alloy adaptor plate to marry into the Toyota Trans Case. Yes the 4JJ is a serious upgrade in both performance and cruising economy. Here is the engine bay now.

 

[Richard Luksozek]

I'm also someone who would like a tach on every vehicle. I have a 1HZ pickup and a couple of 1FZ 70 series without it, and it annoys me.

Is the point of what you are doing to get a factory tach to work in the dash, or is it to have a tach, because I've considered a couple of times adding a tach in the fuel tank binnacle of the 70 series, but not the factory tach.

Very nice to hear from another Land cruiser collector addict. I have a 60, 70 & 80 in my driveway to be restored. 70 is done and now my day driver. The 4JJ engine conversion left the dash with a few gauges not working and hated the thought of putting in after market gauges rather than getting the ones in the dash working so that was my mission. Since I reused the original TC the mechanical speedo was a no brainer, 4x4 light used the original sw, the Reverse light picked up the sw in the 4JJ 5spd, Oil Pres used a spare bung where the 4JJ pr sw is mounted and water temp needed a new sender. That left the tacho and since I ditched the 1HZ I had to find a new way to send a signal to the original Toyota tacho. I've also replaced the dash in my 80 with one that has a tacho so needed that sorted and will test the solution works with the original tacho in the 60 just to check all the Toyota Tachos are basically the same.

 

[Richard Luksozek]

My $14 inductive proximity sensor is on its way but I won't see it until late in the week. I decided to test a another input signal and just so happened I had a speedo sender unit for my '93 80 series. (Speedos were electric for 78,79 and 80 series from mid 92 onwards). This is a 3-wire sensor (12v+, Gnd , Signal) Hooked the unit up to my Makita drill and my DSO showed 131hz 12v pulsed signal. Connected it to the tacho and the tacho showed about 300rpm. Max rpm of the drill was pretty slow but very encouraging result. Chat more when I get/test my sensor.

 

[Richard Luksozek]

Well its been a bit over a yr since i started this thread and although it stated well and I got all the info to make it work, putting into "Practical" reality turned out to be more difficult. Having a sensor hanging around the engine bay with a convoluted series of bits on the crank pulley for the sensor to pickup pulses just wasn't very practical. So off I went just using the Troopie exploring the Oz outback and in a blink of an eye 13 mts slipped by. I'm now back with a fresh idea and few other problems to fix. Oil pressure gauge and engine water temp as well as the ANNOYING tacho.

Here is my plan. I plugged in my ODB scanner doing some basic service checks and noticed I had water temp, oil pressure and revs all in my ECU. So I plan to develop and ODB interface and pick out the registers for these three readings and convert the ODB value into and Analogue signal for the Troopie gauges. Sounds nice and clean so how hard can it be.. practically?? Will let you know when I work it out but I hope there are some ODB experts reading this. Just in case you are confused, the Troopie has an ISUZU 4JJ conversion with engine harness and ECU.

 

[Richard Luksozek]

A short update:
I appreciate this thread is not for everyone and perhaps should be under another section but for anyone that has a Troopie (or 80) with an engine swap away from the traditional Toyota motors, will find some of the gauges not working and may find this useful.

Hardware over view:
The heart of my project is the Arduino MEGA 2560 that is required to handle all the number crunching and I/O traffic. To connect to the ECU I have decided on the Sparkfun ODB2-UART board for a number of reasons that I will clarify a bit later. This board has a 9 pin DB9 socket that requires a DB9 - ODB2 cable (Make it or buy from Sparkfun) to connect to the ECU ODB2 port. Computer connection is via the FTDI Basic board that has a mini USB socket. A standard USB cable will connect it to your computer. The FTDI board has a 6 pin connector that plugs into the ODB2-UART board. Of these 6 pins you will only be using 3. GND, TX and RX. More on this later. To convert the Digital signals to the analogue signals required for the Toyota gauges (Tacho, oil pres and Water Temp) you will need D/A (Digital/Analogue) converters. One for each gauge. I have chosen the MCP4725 but there are many others. This connects from your MAGA 2560 to the Toyota dash instrument More on the calibration later. To power all this you will need 5vDC and I have chosen to used the LM2596 regulated Buck controller to ramp down the car 12v to a stable 5v. This is rated at 3 amps so is plenty big enough. The car 12v comes from pin 16 of the ODB2 cable and connects to pin 9 at the DB9 socket. From there is feeds onto the ODB2-UART board to a terminal labeled VBAT. This is where you pickup 12v to feed into the LM2596 and rotate the trim pot so that you get 5v on the output. More on this later. I have also decided to include an LCD screen to pickup and display other ECU data. The screen I have chosen is a NEXTION NX8048P070 which can connect to the MAGA 2560 and powered by 5v. Its quite an up market touch screen but there are many simple and cheap LCD screens to choose from as well. However you don't need a screen unless you want to display ECU codes. I want to display MAF, Boost, Fuel Pres and Fault codes. More on this later. Ok thats it for now and thats it for the hardware you need appart from a small enclosure. More on this later.

 

[Richard Luksozek]

Another update, this time an OOOps correction.
On further investigation and testing of the gauges (Temp and Oil pres) it appears they are NOT signal input gauges like the Tacho. (See above for Tacho testing results.) The dash Temp and oil gauges require a variable resistance type sensor that changes its resistance with changes to the process being measured and connects the gauge to chassis earth. eg Thermister for measuring temperature so as the temp increases the resistance of the sensor reduces. (negative coefficient). The oils sensor is the same, as the pressure increases the resistance decreases. So what are the values? Temp sensor is @20 Deg C its 710 ohms and @92 deg C (hot engine temp) its 86 ohms and gauge was showing is a bit below mid range. Same with oil pres, when sensor is reading 86 ohms the oil pres gauge is mid range and representing approx 2000rpm. So that means I have to change change two of the MCP4725 for one AD5204 (4 channel Digital Potentiometer). One channel each for Temp and oil and two spare. Printed and enclosure for the parts but will now need to modify it for the AD5204 boards once they arrive. That's it for now.