900 L4-1985cc 2.0L (1982)
Speed Relay (Turbo Only): Description and Operation
Fig. 31 Speed Relay Terminal ID
Speed governed fuel boosting takes place at engine speeds above 3800 RPM. The pulse ratio was either 85% or 92%.
At engine speeds above 3800 RPM and before the throttle butterfly has passed the 72° position, there is a signal from terminal 1 in the throttle position
sensor to terminal 31A in the speed relay, Fig. 31. Therefore, terminal 7 in the ECU is grounded via terminal 87 in the relay, and terminal 31 in the
speed relay is grounded via terminal 31 in the time relay, resulting in a pulse ratio of 85% being selected.
If the throttle butterfly passes the 72° position, the circuit to terminal 31A in the speed relay is broken, terminal 11 in the ECU is grounded via
terminal 3 in the throttle position sensor, terminal TK in the AC relay and terminal 11 in the time relay, resulting in a pulse ratio of 92%.
