Wiring the GRT EIS 4000 Tach leads....

[comfortcat]

OK,

1. I have a regular key switch for my ignition. ACS standard Off, L, R, Both, and Start connected to my O-320 with std Bendix mags.

2. Wire is shielded as recommended by AeroLetric from key switch to bendix mag p-lead.

3. I have GRT EIS 4000 that needs two tach wires (L and R) that go to P-leads on Bendix Mags. These wires are NOT shielded.

Question:

A) should I just run the single wire to the mag and hope I get no noise? or
B) send the tach connections to the key switch for connection?

Note: Both tach wires have an inline resistor per installation instructions.

Thanx

CC

[BobTurner]

I ran my unshielded wires from the EIS to the key switch. Keeps the wires shorter, no firewall penetration. No noise issues.

[rzbill]

Originally Posted by BobTurner

I ran my unshielded wires from the EIS to the key switch. Keeps the wires shorter, no firewall penetration. No noise issues.

+1......And dont forget the resistors.

[comfortcat]

Thanks guys. By the way, GRT gives me two values for the resistors, but I can not find instructions on which one to pick. Is this trial and error?

Which one is a good start?

CC

[rzbill]

I don't remember the multiple values because it has been a couple of years. I was looking at that area behind the panel this past weekend and do remember they were marked 27K ohms. I imagine that was one of the sizes from GRT documentation.

[KatieB]

Both the 27K and 39K ohm resistors will work for the tach. We supply 27K resistors as standard. The 39K resistor note in the EIS manual basically amounts to TMEI (too much engineering information). It's a throwback to an older version of the EIS. Sorry for the confusion!

[NYTOM]

Miss "Katie B" this thread came just at the right time. Just finishing up my wiring and the last wire from my 4000 is that yellow tach wire. Well stupid me went out years and years ago and bought a state of the art ignition system.
Best thing since sliced bread they said. It's called a Lasar. Ever hear of it?
Well I spent too much to abandon it now.
There's one brown wire coming off its control box marked "Tachometer ".
Would just connecting it to the yellow tach wire from the 4000 complete this particular setup or do I have to involve the ignition switch and use any resistors. I've mentioned it around the local aviation community and I'm usually met with a blank stare. I keep putting this task to the bottom of the pile but now I'm at the bottom with nothing to put it under. Any suggestions? ( other than trashing the Lasar).