Mazda RX-7 (FC) Electrical Wiring Diagram

This detailed wiring diagram manual provides comprehensive electrical schematics for the Mazda RX-7 FC (1985-1992). It covers all major electrical systems, including engine management, lighting, ignition, charging, and interior electronics. With clear circuit diagrams and component locations, this guide is essential for troubleshooting, repairs, and modifications. Perfect for mechanics, restorers, and enthusiasts looking to maintain or upgrade their RX-7 FC's electrical system.

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1. Ignition System Issues

Ignition Coil Failure – Over time, ignition coils would become ineffective, causing rough running, misfiring, and loss of power.

Bad Spark Plug Wires – High-voltage wires would wear out over time, causing erratic spark.

2. Sensor Issues

Coolant Temperature Sensor – Frequently failing, affecting fan operation and potentially causing the engine to overheat.

Throttle Position Sensor (TPS) – Could give incorrect signals, causing rough idle and throttle response issues.

Oil Pressure Sensor – Could give false readings or fail entirely, potentially misleading the owner about actual oil pressure.

3. Alternator and Charging System Issues

Weak Alternator – The RX-7 FC’s stock alternator might not be able to handle the load, especially if additional electrical equipment is installed.

Worn Alternator Brushes – Over time, the alternator would lose efficiency, causing problems with charging the battery.

Bad Ground Contacts – Oxidized or loose connections would cause unstable voltage and electronic malfunctions.

4. Wiring and Contact Failures

Overheating and Oxidized Contacts – High temperatures under the hood would cause the contacts to oxidize, causing problems with connections in the wiring harnesses.

Chafing Wiring Harnesses – Especially where they attach to the body, which could cause short circuits.

Old Wire Insulation – Became brittle over time, causing short circuits and malfunctions.

5. Lighting and Dashboard Problems

Failure of the Instrument Cluster – Over time, individual gauges and indicators on the dashboard could stop working.

Burning Instrument Cluster Circuits – A common problem, especially if the vehicle has been overheated.

Bad relays and fuses – Over time, these could fail, causing problems with lighting and other systems.

6. Central locking and windows

Bad window motors – Over time, these would lose power or fail completely.

Bad central locking – The central locking motors and relays could stop working due to wear and tear.