This shows the internals of the IMR, the Ignition Monitoring Relay. The operation is pretty basic as you can see. It utilises a LTC1050, a  Precision Zero-Drift
Operational Amplifier with Internal Capacitors. A common failure is contact resistance of the Relay contacts. The contacts carry the load for Injector current for a batch of 4 Injectors, so substantial current is flows at times.