tacho interface swap

[cbr600teardrop]

i have a 94 car with a 90 ecu and 90 dash tach so im putting the tacho interface on the 94 coils but what about the Ignition Module do i us the 94 or 90 or do i mod the wires on the 94 also the wiring harness is 94 any body that has done these i would love some step by step instructions and pics if ya got them. thanks to every one that can help

 

[e85_4g63]

So you have a 94 car and turbo harness, with a 90 ecu and gauge cluster correct? If your already have the wiring harness mod'd for the 90 ecu, you'll want to use all the 94 parts. The ignition has to match the wiring harness.

 

[steve]

Why the extra work. If you stayed with the 94 dash cluster and used the 94 PTM and coils all you would have needed to do was swap pins 6 and 14 to use the 90 ECU.

 

[blazinglaser_90]

agreed I had a 90 eprom in my 93 harness and ignition setup'd car and all was well w/out any wiring changes

 

[cbr600teardrop]

i don't have the 94 dash well i do but its broke so im using the 90 dash and the tach signals are totally different between the two years so i ether have to send my ecu back to key diver dsm chips or put my tacho interface on the 94 coils but im wounding how do i do that and what do i do with the Ignition Module because i have to use the 94 as well .

 

[blazinglaser_90]

my dash is a 90 dash and its in a 91 -94 harness car and it works fine. If you would wire up the car for the 91-94 and use your 90 cluster u'd be fine b/c the tach will work either way due to it being the same signal just the 90 needs an adapter to clean up that signal due it coming off the negative side of the coil rather then the power transistor

 

[steve]

Go get a working 91+ gauge cluster or fix yours. Your wasting your time with the 90 cluster.
Jeff doesn't sell conversion boards for 90 ECUs, he sells the circuit for using a 91+ ECU in 90 cars.

 

[cbr600teardrop]

ok jeff at dsm chips told me how thanks guys heres what he said to do.


1) remove the tach driver module from your 1990 coilpack and attach it to your 1994 coilpack. Its only 2 wires, one to each coil. Then, cut the white tach wire loose from the 1994 transistor plug, and attach it instead to the tach output of the 1990 tach driver module.
2) Or, send the ECU back to me and I'll unconvert it, so it is plug-n-play for a 1994 wiring harness and coilpack. The only thing I'm not sure on is if the 1990 tach will work with the 1994 coilpack. worst case you will need to swap the tach.

 

[steve]

1) remove the tach driver module from your 1990 coilpack and attach it to your 1994 coilpack. Its only 2 wires, one to each coil. Then, cut the white tach wire loose from the 1994 transistor plug, and attach it instead to the tach output of the 1990 tach driver module.

Looking at the 90 and 91+ coil packs should have shown you how the 90 tach interface connected to the coils. Make sure you reconnect the red and yellow wires to the same non-common posts on the coils that the Power Transistor wires connect to. The white is the tach output.

2) Or, send the ECU back to me and I'll unconvert it, so it is plug-n-play for a 1994 wiring harness and coilpack. The only thing I'm not sure on is if the 1990 tach will work with the 1994 coilpack. worst case you will need to swap the tach.

How is he going to unconvert your 90 ECU into a 90 ECU. Did you tell us the wrong thing or him?

 

[cbr600teardrop]

ok i bought a 94 eprom stage 3 ecu from him and at the time it was for a 90 car but it got totaled and now i have a 94 with the 90 6 bolt motor in it so he converted it from a 94 to a 90 so now he could convert it back if i wanted

does any one have a pic of the tach noise filter on a 90 and how to wire it in as well

 

[steve]

And you though it would be confusing if you told us you have a 94 EPROM that had been converted to run in your 90 so instead you told us you had a 90 ECU.

Well you should have more than enough information at this point to make it work.

 

[cbr600teardrop]

does any one know where the tach noise filter is and have a pic of it on a 90 and how to wire it in as well

 

[steve]

The 1990 FSM says it (B-03) connects via pin 2 (the white wire I believe) to the white wire from pin 3 on the coil connector in parallel with the wire wire to pin 109 on the ECU. Pin 1 (the black wire I believe) on the filter is connected to the gauge cluster and the engine speed adjustment connector A-54.

It shows that it is one of the three connectors on the engine harness right after the ISC branches off. The other two are the knock sensor and the EGR Temp sensor. I believe that it's bolted to the firewall side of intake manifold but I've never seen it in place. It does need to be attached to something grounded. The case is a ground for the cap inside.