PSA: Megasquirt + EDIS + Autometer Tach (clean signal)
Posted: Mon Apr 05, 2021 5:32 am
I've been using an Equus 3 3/8" tach (Autozone special) for over 4 years and decided it was time for an upgrade. After a trip to Summit (yes, we have a retail store here in Texas) I was the proud owner of an Autometer 5" tach.
Yes, its too big. Yes, I can only utilize half of it. Yes, the shift light is overkill. But it brings me joy.
ANYWAYS! I connected the tach to the TACH out put of the EDIS module. The same one I used on the Equus unit without issue. The Autometer unit did not want to play nice. At first I though I had a bad unit. After hours of testing with a DSO and reading internet stuff I decided to try a different approach.
If you are using an Autometer tach with a Ford EDIS ignition system you can use the PIP circuit (see diagram below) or tap MS 2 pin #24 for a tach signal. This circuit produces a clean 5V square wave. Even though Autometer advises against using a 5V signal it seems to work just fine.
I hope this helps someone in the future. Happy Motoring!
-Nick-
Yes, its too big. Yes, I can only utilize half of it. Yes, the shift light is overkill. But it brings me joy.
ANYWAYS! I connected the tach to the TACH out put of the EDIS module. The same one I used on the Equus unit without issue. The Autometer unit did not want to play nice. At first I though I had a bad unit. After hours of testing with a DSO and reading internet stuff I decided to try a different approach.
If you are using an Autometer tach with a Ford EDIS ignition system you can use the PIP circuit (see diagram below) or tap MS 2 pin #24 for a tach signal. This circuit produces a clean 5V square wave. Even though Autometer advises against using a 5V signal it seems to work just fine.
I hope this helps someone in the future. Happy Motoring!
-Nick-