Mitsubishi 3000GT 1991, Service Manual

Page: 269 / 1146

CRUISE CONTROL SYSTEM Troubleshooting
CHECK CHART
Inspection of control unit power supply circuit
CRUISE
SWITCH
TROUBLESHOOTING HINTS
ECU terminal voltage
DESCRIPTION OF OPERATION
The power is supplied through the ignition switch
and cruise control main switch to the control
unit.
1. When the cruise control main switch is set to
ON with the ignition switch at ON, the current
from switch flows through relay in the
switch. Accordingly, the contact of relay is
closed and the power is supplied to the control
unit.
2. When the main switch is released, it automati-
cally returns to the neutral position. Since the
current from switch
flows to relay the
contact of relay Ry, remains closed.
3. When the main switch is set to OFF, current to
relay is interrupted. This opens the contact
of relay to stop the power supply to the
control unit. When the switch is released, it
automatically returns to the neutral position, but
relay Ry, stays in the OFF state.
4. When the ignition switch is set to OFF while
relay Ry, in the main switch is ON, relay is
forced to the OFF state just like when the main
switch is set to OFF. Even if the ignition switch
is set to ON again, relay stays in the OFF
state until the main switch is set to ON.
NOTE
The numbers beside each connector correspond
to those in the section “HARNESS
AND COMPONENTS LAYOUT”
Terminal
No.
Signal name
Condition
Terminal
voltage
2
Control unit power supply
Main switch ON and neutral position
System voltage
thereafter
Main switch OFF and neutral position
ov
thereafter
8, 14
Control unit ground
At all times
ov
16
Control unit back up power supply
At all times
System voltage
TSB Revision