EDI DIAGNOSIS SERVICE MANUAL NUMBER 22
Page 5E-46 90-860074--1 FEBRUARY 2002
Main Relay
Scan Code: P1625
Blink Code: 1231
Malfunction Indicator Lamp: OFF
ECM
42
WHT/RED
75342
23
RED
b
c
d
g
h
e
f
a-Electrical box
b-Battery 12 Volt To Circuit Breaker
c-Circuit Breaker
d-Main Relay
e-11 Terminal ECM Harness Connector on Electrical Box
f-11 Terminal Connector
g-Ground (–) CKT Pin 42 for Relay
h-12 Volt Power Supply to ECM
CIRCUIT DESCRIPTION:
The Main Relay test monitors whether the power supply was shut off too early or too late
and the condition of the Fuel Shut Off Valve function.
If a signal change from Battery (Switched K15) occurs and the main relay was shut off before
the ECM had given the shut off command (After-Run not completely finished), then there
has been a control unit defect. Over the defect validity check. The defect “main relay
switched-off too early” is reported during the next control unit initialization.
If a signal change from Battery (Switched K15) occurs and the functions for after-run test
has ended with a complete error storage then the main relay is shut off and monitored for
a specified length of time. If the main relay is shut off before the programmed time elapses
then the main relay is functioning correctly. If not, then the defect “main relay turned off too
late” is reported after the ECM does a defect validity check. This test may only be carried
out if no system error exists.
DIAGNOSTIC HELP:
Verify the following:
• Replace the ECM.
Recognition by the ECM of a Main Relay fault influences engine performance as follows:
• No loss of power.
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