Tach Not working

[JAW91]

I have a 1991 Talon but it was manufactured in August 1990, the car has an external oil cooler, the TPS is from a 1990 and the Coil pack is from a 1990, the gauges are from a 1991 though and everything works EXCEPT for the Tach. My question is would the tach be the only thing that shouldn't work if you have 1991 gauges in a 1990? Or would none of them work? (It also says its a 1991 on the title and my sunroof clip is the plastic one, not the metal one)

[007jimmy]

You need the noise filter for the '90 tachometer to work with a '90 ignition system and ECU. Do you have it?

[JAW91]

Yes, but like I said though, the gauges are from a 1991. They are in increments of 10, not 5.

[JAW91]

Anybody know this? The question is what gauges exactly work and don't work when you put a 1991 gauge cluster in a 1990?

[steve]

At this point how do you know that's the original engine? We see people stuffing cheap 90 style engines in 91+ cars all the time.

Check the ECU. You want to know what type/part number it is.
Check for the 90 noise filter which should be attached to the side of the intake manifold stay. It couples the ignition pulse signal from the tach gate on the 90 coil to the ECU and Cluster.

[JAW91]

I know for sure its not the original engine but they would have had to switch the harness too, the noise filter is there and so are the other 90' parts, like the throttle body, external oil cooler, CAS, and Power Transistor. So what I think is that the car itself is a 1991 and the harness and motor are a 1990. Its really weird but it makes sense even if it had a 1990 motor in it before because the car was made in August of 1990 even though its considered a 1991. So I think if I put a 1990 gauge cluster in the tach will start working again but I'm not positive, that's why I came here to try and ask if you guys might know.

[steve]

Originally Posted by JAW91

So what I think is that the car itself is a 1991 and the harness and motor are a 1990. Its really weird but it makes sense even if it had a 1990 motor in it before because the car was made in August of 1990 even though its considered a 1991.

So I think if I put a 1990 gauge cluster in the tach will start working again but I'm not positive, that's why I came here to try and ask if you guys might know.

It's an early 91, the factory switched over to 91's in June of 1990.

Check the ECU, if it's a 91 ECU it won't matter if you install a 90 cluster.

[JAW91]

Will do, if it is a 1991 ECU how do I get my tach to work with the 1990 harness?