Tach pull up resistor only some E67 cals ??

[95wagon]

Long story short , I have an LS7 with GMPP E67

My 1996 Impala cluster works fine with it using a pull up resistor on the tach line .

In my quest to get ECM controlled A/C and cruise I am mucking with a 2007 TBSS cal in a separate E67 ECU

When I run the car with the TBSS cal, the tach does not work .

The pull up is buried in the dash and not simple to access ( or I would just yank it to see)

From what I can see in wiring diagrams, I think both cals use the same tach output terminal

Has any one seen different cals needing and not needing pull up - pull down - or nothing?

The tach settings look t be the same in , EFI LIve , HP tuners and TunerCat .
Because of plus-minus in the different programs, I do have both ECMs licenced in all 3

Thanks for any input

Gerry

[efiharness]

In all of the e67 's that we have used J1-25 is the tach output. If you just add a pin next to it (j1-24 ) connect the two and connect to your tach all is good. there is a
built in pullup resistor in the ecu connected to that pin. Steve

[95wagon]

In all of the e67 's that we have used J1-25 is the tach output. If you just add a pin next to it (j1-24 ) connect the two and connect to your tach all is good. there is a
built in pullup resistor in the ecu connected to that pin. Steve

At the time I put the car together , I was not aware that you could use "42" tied to "25" to get the pull up
BUT the tach works with the outside pull up I did with the GMPP E67 ECM , but not when I plug in the TBSS cal ECM

Any idea why on one but not the other?

They are both set the same , 15 high 15 low type crank

Interesting thing though, while both files show both choices show in HP Tuners, Tunercat, EFI live does not show the "type " choice for the GMPP cal