Here's why:
Compatibility Issues:
* Electrical Connections: The wiring harnesses for the different instrument clusters are likely different. You'd need to rewire the cluster to match your car's existing harness or find an adaptor.
* ECU Communication: The instrument cluster interacts with the ECU, and the communication protocols may differ between your 1994 model and later models. You might need to reprogram the ECU or find a compatible one.
* Speedometer Calibration: The speedometer will need to be recalibrated for the new MPH gauge, as the original KMH one is geared differently. This may involve adjusting the speedometer drive gear or reprogramming the ECU.
* Tachometer Calibration: The tachometer signal may be different between the two clusters, requiring modification to the wiring or ECU programming.
Additional Considerations:
* Compatibility of Other Gauges: Other gauges on the instrument cluster (fuel, temperature, etc.) may also have different functions or signals.
* Dashboard Fit: The later model cluster might not fit perfectly in your 1994 Impreza's dashboard. You may need to modify the mounting or use an adapter.
Alternatives:
* Custom Instrument Cluster: Consider a custom instrument cluster built specifically for your 1994 WRX STI. This allows you to choose the gauges, colors, and functions you want.
* Aftermarket Gauge Kit: Install an aftermarket gauge kit to add the desired gauges to your existing dashboard. This might be a simpler and more affordable option.
Before You Begin:
* Research the specific instrument clusters for 1994 and later Imprezas to understand the differences and potential compatibility issues.
* Consult with a qualified mechanic or automotive electrician to assess the feasibility of the swap and discuss the potential challenges.
* Be prepared to invest significant time, effort, and potentially money to complete the project successfully.
Overall, swapping the instrument cluster is a challenging project. While it is possible, it requires a significant amount of work and knowledge. Consider the alternatives before embarking on this complex modification.
