Just want to know what drives the LJ-78 tach? Off transmission? from injection pump?
Thanks.
Thanks.
What runs the LJ-78 tach? (1 Viewer)
- Thread starter coldtaco
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Its off the injector pump....
Wouldn't it be less accurate if runs on injection pump? Running on transmission make more sense to me. I'm open to learn more about how it runs on IP.
If its a 2lt engine or a 2lte there is a speed sensor in the pump.....
The 2lte one uses it for ECU and Tacho...
The 2lt one is just for tacho....
Cant see why it wont be any different to a flywheel pickup...
Its all spinning directly off the engine and uses a hall effect pickup... Just depends on how many pulses per rev.....
The 2lte one uses it for ECU and Tacho...
The 2lt one is just for tacho....
Cant see why it wont be any different to a flywheel pickup...
Its all spinning directly off the engine and uses a hall effect pickup... Just depends on how many pulses per rev.....
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There is also a crank position sensor on the 2LTE on the side of the block that helps to time time the injection pump.
~John
~John
Thank you for all of your information!
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Just trying to figure out how to make the tach run off of a 1HD-FT and I have a tach from a BJ-70 and LJ-78.
Thanks.
Thanks.
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The tach on a 3B runs by counting the teeth on the flywheel. IF the 1HDF-T has the same number of teeth on the flywheel, which I doubt it has, then you can use a 3B tach and sensor.
The LJ78 runs off the pump - same deal, counts teeth but there's less of them. Not sure about what the number of pulses is per revolution.
~John
Most fitting thread I found to pose this relatively simple question.
IF an HZ IP has a three wire extension, one being fuel cut and the other two running to the block side of the pump, does that automatically mean it's fitted with the tach pickup?
IF an HZ IP has a three wire extension, one being fuel cut and the other two running to the block side of the pump, does that automatically mean it's fitted with the tach pickup?
Did you come right with the LJ 78 tach ? I found a LJ78 cluster with tacho but sofar the tacho does not work in my HDJ 75 series which did not have the tacho.
Interesting information here. I have been wanting to figure out a way to run my original LJ78 tach with the ECU signal from my VW engine, but have drawn a blank so far. I found a thread a year or so ago that said how many teeth the LJ78 pickup sensor used, but I can't seem to find it now and don't remember the number.
I did find this, which is from an LN130 Hilux Surf but should be pretty much the same. This seems to indicate that the pickup sensor on the IP is a 5V sinusoidal waveform with only two wires...leading me to believe that rather than Hall Effect it is an inductive sensor. Unfortunately that doesn't answer the question of what type of signal the ECU sends to the tachometer. If anyone reading this has a running 2L-TE and access to an oscilloscope and could check the waveform on the ECU tach output that would be awesome!
Edit: just found this thread: Toyota 2LTE error codes - https://forum.ih8mud.com/threads/toyota-2lte-error-codes.201623/post-3002445
Shows that TAC -> ground should have pulse generation when the engine is running. Not exactly sure what form that takes, but "pulse generation" makes me think square waveform.
Edit: just found this thread: Toyota 2LTE error codes - https://forum.ih8mud.com/threads/toyota-2lte-error-codes.201623/post-3002445
Shows that TAC -> ground should have pulse generation when the engine is running. Not exactly sure what form that takes, but "pulse generation" makes me think square waveform.
GTSSportCoupe
2LTE abuser
Fantastic info! Another piece of the puzzle in place, now if only there was similar information about the tachometer signal output...
GTSSportCoupe
2LTE abuser
Haha! Sarcasm? It's the NE output they talk about I believe? Page 18 of first manual and 21 of second (as written on page bottoms).
As the NE pickup is an input to the ECU, what you need to know is what the ECU is actually putting out to the tach, correct? I do have a scope at home.....maybe I'll have a look at that signal next time I have my gauge cluster out for bulb replacement.
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No sarcasm intended, the NE sensor information is very useful, but I don't think that is the signal that gets sent to the tachometer. I'm pretty sure the ECU modifies the signal before it gets sent to the gauge cluster.
I'm cross referencing from a thread I started trying to diagnose a problem with my tachometer ( '96 KZJ78). I'm pretty sure, though not positive, I nailed my problem down to a physical problem with the tachometer as one of the springs looks bent, but I'd like to try and confirm it's not a problem with the ECU signal given the part is $400 and I have no photos of a working tachometer to ensure mine really is bent and isn't supposed to look that way.
KZJ78 Tachometer not functioning - https://forum.ih8mud.com/threads/kzj78-tachometer-not-functioning.1276291/
I'm pretty sure, though not positive, I nailed my problem down to a physical problem with the tachometer as one of the springs looks bent, but I'd like to try and confirm it's not a problem with the ECU signal given the part is $400 and I have no photos of a working tachometer to ensure mine really is bent and isn't supposed to look that way. What would this signal from the ECU look like and how would I test it? The signal I found that I *think* is the right one measures out at 4.7 volts on my multimeter on it's dc setting and does not vary with engine speed.
KZJ78 Tachometer not functioning - https://forum.ih8mud.com/threads/kzj78-tachometer-not-functioning.1276291/
I'm pretty sure, though not positive, I nailed my problem down to a physical problem with the tachometer as one of the springs looks bent, but I'd like to try and confirm it's not a problem with the ECU signal given the part is $400 and I have no photos of a working tachometer to ensure mine really is bent and isn't supposed to look that way. What would this signal from the ECU look like and how would I test it? The signal I found that I *think* is the right one measures out at 4.7 volts on my multimeter on it's dc setting and does not vary with engine speed.
The best way to test the signal would be to hook it up to an oscilloscope and see if it is putting out a waveform. I don’t know what the waveform is supposed to look like, but would really like to know.
Maybe I can find somebody that has one, but doubtful. All my friends make me look like a mechanical genius, and the few car guys I know I'd guess are way more heavily steeped in static dc stuff (i.e., the circuit either does or does not have a 4V signal) and nothing with a wave. The cost of scope appears to be about the same as the part, so at that point I may as well just cross my fingers and hope the part I'm ordering fixes the problem. That said, I hate replacing parts without knowing they are actually the culprit.
I’ve been wanting to try out this: EspoTek Labrador Board – EspoTek Labrador - https://espotek.com/labrador/product/espotek-labrador-board/
Regular oscilloscopes are really quite expensive, but I think this has all the functionality needed for basic automotive applications. I have actually corresponded with the designer, he was very helpful in answering my questions.
Regular oscilloscopes are really quite expensive, but I think this has all the functionality needed for basic automotive applications. I have actually corresponded with the designer, he was very helpful in answering my questions.
