Mercury MerCruiser D2.8L D-Tronic Service Manual page 620

EDI DIAGNOSIS
Glow Plug Auxiliary Relay, If Equipped
Scan Code:
Blink Code:
Malfunction Indicator Lamp:
CIRCUIT DESCRIPTION:
The Glow Plug Main Relay (or Actuator) and the Glow Plug Auxiliary Relay are inside the
electrical box of the engine. The ECM determines if, when and for how long a period the glow
plugs (relays) should be activated based on coolant temperature information from the ECT.
This processing by the ECM is done before, during and after the engine is started. It is the
relay that controls the large amount of amperes needed by the glow plugs. Concurrent with
supplying power to half of the glow plugs the Glow Plug Relay Actuator relay activates the
Glow Plug Auxiliary Relay. The Auxiliary Relay's coil is energized closing a switch which
thereby supplies current to the remaining glow plugs.
The ECM closes a ground path circuit for the Glow Plug Lamp whenever the system is
operating.
A failure in the Glow Plug Auxiliary Relay circuit should set a Scan Code P1640.
50
3
Page 5E-52
BRN
b
c
RED
86
30
b
RED
85
87
BLU/YEL
a - Engine Main Relay
b - Circuit Breaker
c - Glow Plug Main Relay
d - Glow Plug Auxiliary Relay
e - Engine Harness Connector
f - 16 Terminal Instrument Harness Connector
g - To Glow Plug Lamp
CKT PIN
ECM controlled Glow Plug Relay Ground (–)
ECM controlled Ground (–) for dash panel Glow Plug Lamp
P1640
No recognition by ECM.
OFF
BRN
87
85
d
30 86
BRN
BLU/BRN
a
87
85
SERVICE MANUAL NUMBER 22
g
f
BLU/BLK
BLK/YEL
e
NAME
90-860074--1 FEBRUARY 2002
ECM
50
3
75476