1G Tach question 90 vs 91 gauge cluster

[HondaKiller]

Okay, so I swapped my 90 guage cluster out for a 91 and the tach doesn't work.

I know the two are not compatible straight away with the inverted tach signal. I know if you are swapping ECUs or wiring harness and stuff you need to switch pins 6 and 14 to make it work. I need to know if swapping these two wires on my 90 ECU will make my 91 tach work without messing something else up.

Or if there is a different way to make the tach work that I haven't heard of it would be appreciated.

I'm going to try swapping the tach mechanism in the clusters, maybe that will work...

 

[DevilSperm]

i belive one goes through a filter and the other reads off the CAS or something. I think it's possible to make it work but its a bi***. Might wait for someone that's actually done it to reply though

 

[Lordpaxin]

The 90 model coil pack has a separate tachometer circuit mounted right on the coil bracket.
The 91+ has the same circuitry built into the Power TR unit.

That's one of the problems with the JDM cyclone engine installed, if they try to keep cyclone coils.

I rewired my JDM coils to work with USDM wiring, that's how I know this.
Your manual will have wiring diagram for tachometer, and for the wires on the power tr that match wires on the 90 model tach junk, if your determined, match these wires up.

Pins 6 and 14 aren't related to the Tach, they are for the IPS and MAF reset signals that swapped between 90 and 91.