EDI DIAGNOSIS
SERVICE MANUAL NUMBER 22
Page 5E-50
90-860074--1 FEBRUARY 2002
Glow Plug Main Relay (Glow Plug Relay Actuator), If Equipped
Scan Code:
1635
Blink Code:
No recognition by ECM.
Malfunction Indicator Lamp:
OFF
ECM
50
BLU/BLK
75476
3
BLK/YEL
86
30
87
86
30
87
85
BRN
BLU/YEL
RED/YEL
RED/YEL
BRN
BRN
BLK
BLU/YEL
a
b
c
d
e
f
b
85
RED
a -
Engine Main Relay
b -
Circuit Breakers
c -
Glow Plug Main Relay
d -
Glow Plug Auxiliary Relay
e -
Engine Harness Connector
f -
To Glow Plugs
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
plug 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 engines glow plugs this relay actuates the Glow Plug Auxiliary
Relay which handles current to the remaining glow plugs.
A failure in the Glow Plug Main Relay circuit should set a Scan Code P1635.
CKT PIN
NAME
50
ECM controlled Glow Plug Relay Ground (–)
3
ECM controlled Ground (–) for dash panel Glow Plug Lamp