Service manual

90-898303 2-16

ELECTRIC FUEL PUMP

The ECM contains a fuel pump driver circuit that provides power to the electric

fuel pump (2 speeds). The fuel pump does not have its negative terminal (-)

“red/purple wire” grounded to the pump housing. The fuel pump positive

terminal (+) “red wire” and the negative terminal (-) are at 12 volts with the

ignition switch in the off position for a zero differential. When the pump is on,

the negative terminal is brought down to near ground (i.e. 1.5 volts at high

speed). The fuel pump is run at two speeds by the ECM. It is run on slower

speed during slow speed engine operation, and at a faster speed when the

engine is operated above approximately 2000 RPM.

WATER SENSING SYSTEM

The system consists of a water separating fuel filter (starboard side

powerhead), sensing probe (bottom of filter) and a water sensing module

(below ECM box). The water sensing module has four wires:

• Purple - Connects to 12 volt power supply.

• Light Blue - Connects to lube alert, which sounds the warning horn when

activated.

• Tan - Connects to sensing probe.

• Black - Connects to ground.

EFI Detonation Control System

2.4L & 2.5L (1987–1999)

The Detonation Control System consists of a detonation control sensor

located on the port side cylinder head and a detonation control module

mounted on the engine. The detonation control module has seven wires:

• White/Blue - Connects to knock sensor, transmits knock signal to control

module.

• Green - Connects to #2 primary wire. The primary voltage signals the

controller to monitor combustion “noise” during a window of time.

• White/Black - Two of these wires connect to the switch boxes bias circuit

terminals. A third wire is spliced in one bias circuit (inner switchbox) and

connects to the idle stabilizer module.

• Gray/White - Connects to the ECM; signals ECM to enrich fuel mixture

when knocking occurs.

• Purple -12 Volt power supply.

Notes

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