What Happens if Power Transistor is Not Grounded

[Flash]

I searched and read that the car will run fine. I'm trying to figure out why my monster tach won't get a signal. I did pull apart the engine and I have a very good idea that I forget to ground the power transistor when I installed a new intake manifold.
So if the power transistor is not grounded, will my mega tachometer not get a signal? Car still runs, and I can still log RPM on DSMLink. I'm using the same white wire off the ECU I used to get RPM signal for my AFC in the past.

 

[b00stedtalon2]

What I do for aftermarket tachs is use the crank signal wire off the CAS or at the ECU (same thing). DSMlink gets its rpm for this wire, so if your RPM gauge is spliced into it, it should work.

 

[Flash]

Auto Meter said use the white wire off the power transistor in pin #4. So I did that. Same wire as off the ECU I suppose. I just know my power transistor is not grounded.

 

[daren_p]

By not grounded, you mean throught the bracket? I don't think it needs to be grounded this way, reason being I painted my bracket this spring & then was wondering if this would be an issue. I looked at the wiring schematics & from what I could tell its grounded through a wire in the harness & the bracket itself doesn't need to be grounded. If this isn't the case, I'd like to know as well.

 

[knochgoon24]

Wouldn't the way to test be to unbolt the transistor, start the car, then place a voltmeter between the bracket on the transistor and the intake mani. If there's a voltage difference, it should be grounded. Or am I wrong?

 

[Flash]

By not grounded, you mean throught the bracket? I don't think it needs to be grounded this way, reason being I painted my bracket this spring & then was wondering if this would be an issue. I looked at the wiring schematics & from what I could tell its grounded through a wire in the harness & the bracket itself doesn't need to be grounded. If this isn't the case, I'd like to know as well.

Yes. I installed a Magnus manifold and left the power transistor dangling.

 

[JayRolla]

Me too, mine is just dangling in the engine bay not mounted. It does not get its ground from the mount so it should be fine.

 

[Flash]

I'm starting to think that the 1g power transistor doesn't need to be grounded like the 2g. Am I right?