Tachometer Help Please

[Silvia_Drift]

Hey guys, I need some help fixing my tach. The car is a '90, with a '96 KA-T installed. I swapped in a DOHC cluster and the tach still didn't work.

The wierd thing is that the signal is coming through to the ECU. When I put the tester on the red/yellow tach wire that goes to the ECU, the voltage was raising when I revved the engine like its supposed to.

I was thinking that maybe the tach was just broken but it seems like this isn't the case. The SAFC 2 isn't reading anything for the RPMs. One thing I did notice is that it is getting a signal for Inst1 and that seems to be the RPM. It also raises when I hit the gas. Any ideas?

Any help is appreciated, thanks.
Modified by Silvia_Drift at 10:34 PM 3/14/2007

[180fan]

is there a signal coming from the ecu to the tach? it's possible you've tapped the wrong wire too.

[Silvia_Drift]

I have not directly checked the signal at the back of my tach but I will. The thing is, I thought that even if the tach wiring is screwed up, the SAFC 2 would get a signal since it is connected directly to the ECU. Also, when my friend looked at the S13 wiring diagram, he said that if the fuel gauge signal is coming through, then the tach signal is also coming through. I am so confused lol.

[Silvia_Drift]

Hmm, is it possible that even though the tach ECU wire is getting a signal, and the SAFC 2 is connected directly to this wire, the body harness connection might be messing up the connection somehow?

[bias]

May sound dumb, but did you check the dash harness to the ecu? I had to move my ecu and disconnected the dash harness to the ecu by accident.

[HPR]

Hey guys, I need some help fixing my tach. The car is a '90, with a '96 KA-T installed. I swapped in a DOHC cluster and the tach still didn't work.

The wierd thing is that the signal is coming through to the ECU. When I put the tester on the red/yellow tach wire that goes to the ECU, the voltage was raising when I revved the engine like its supposed to.

I was thinking that maybe the tach was just broken but it seems like this isn't the case. The SAFC 2 isn't reading anything for the RPMs. One thing I did notice is that it is getting a signal for Inst1 and that seems to be the RPM. It also raises when I hit the gas. Any ideas?

Any help is appreciated, thanks.

Modified by Silvia_Drift at 10:34 PM 3/14/2007

The wire you tested... is it red/yellow or yellow/red? The tach wire is YELLOW w/ red stripe. Also how did you test the this wire? Tachometer wire should not read higher voltage when you step on the gas, but rather a faster pulse since it is an AC signal.

Did your tach work before with the old motor in it?