Tach Signal?
Moderators: JeffC, rdoherty, stieg, brentp
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AE86 MJLJ user
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- Joined: Thu Dec 30, 2004 4:43 am
Tach Signal?
Hey, i was wondering what some of the reasons could be for the MJLJ to not get a tach signal from the EDIS module. I am pretty certain that it is wired correctly and the module is brand new so there is nothing wrong there, yet when the starter is turning the engine over, the MJLJ reads the engine speed at 0 RPM. What could be wrong?
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AE86 MJLJ user
- Posts: 0
- Joined: Thu Dec 30, 2004 4:43 am
Hey guys i really need some h
Hey guys i really need some help on this. If i cant get this to work im gonna go with a MSnS setup.
With the MJLJ and megasquirt,
With the MJLJ and megasquirt, you need to hook it up this way:
EDIS PIP -> PIP on MJLJ
EDIS SAW -> SAW on MJLJ
Tach out on MJLJ -> Tach in on Megasquirt.
This is how I have mine setup.
As an experiment, you should be able to start your engine with the megasquirt by connecting it's tach input to the PIP line on the EDIS module - the EDIS module will run at 10 degrees.
You should be able to piggy back the PIP input on for the MJLJ to verify you're getting a signal, then you should be able to verify the runtime screen.
If you have something wrong with your tach-out circuit on the MJLJ, you won't get a signal to the Megasquirt, and things won't work that way.
EDIS PIP -> PIP on MJLJ
EDIS SAW -> SAW on MJLJ
Tach out on MJLJ -> Tach in on Megasquirt.
This is how I have mine setup.
As an experiment, you should be able to start your engine with the megasquirt by connecting it's tach input to the PIP line on the EDIS module - the EDIS module will run at 10 degrees.
You should be able to piggy back the PIP input on for the MJLJ to verify you're getting a signal, then you should be able to verify the runtime screen.
If you have something wrong with your tach-out circuit on the MJLJ, you won't get a signal to the Megasquirt, and things won't work that way.
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AE86 MJLJ user
- Posts: 0
- Joined: Thu Dec 30, 2004 4:43 am
Tried splitting signal betwee
Tried splitting signal between megasquirt and megajolt and does not work. Car starts with just PIP signal and no megajolt attached. However, when the megajolt is attached, it does not start.
Hm. there may be too much cur
Hm. there may be too much current draw on the PIP line to drive both.
However, there is another way to test it.
The EDIS module has an "IDM" output, pin #2, which is a diagnostics signal. You can hook the Megasquirt tach input to this line, and hook the MJLJ PIP line to the EDIS PIP connection.
The only thing is the IDM output has a slow pulse when the car is not running, like a "hello I'm alive' ping. The megasquirt will interpret this and fire the injectors, so while you're testing it this way you don't want to leave your engine to 'on' without the engine running, or you'll flood the cylinders. It's not a big deal if you start the engine right away.
So try testing it this way. You should be able to get the engine running, and also get a valid PIP signal into the MJLJ, and therefore be able to view it on the runtime screen.
Remember, this is only for diagnostics purposes, I don't propose permamently leaving it this way.
Let us know what you find out.
Brent
However, there is another way to test it.
The EDIS module has an "IDM" output, pin #2, which is a diagnostics signal. You can hook the Megasquirt tach input to this line, and hook the MJLJ PIP line to the EDIS PIP connection.
The only thing is the IDM output has a slow pulse when the car is not running, like a "hello I'm alive' ping. The megasquirt will interpret this and fire the injectors, so while you're testing it this way you don't want to leave your engine to 'on' without the engine running, or you'll flood the cylinders. It's not a big deal if you start the engine right away.
So try testing it this way. You should be able to get the engine running, and also get a valid PIP signal into the MJLJ, and therefore be able to view it on the runtime screen.
Remember, this is only for diagnostics purposes, I don't propose permamently leaving it this way.
Let us know what you find out.
Brent