Code No.P0578:
Cruise Control Switch Stuck Code No.P0579: Cruise Control Switch Range
OPERATION
This circuit judges the signals of each switch (SET, RESUME and CANCEL) of the auto-cruise
control switch. The engine-ECU detects the state of the auto-cruise control switch by sensing
the voltages shown below.
When all switches are OFF: 4.7 - 5.0 volts
When the MAIN switch is ON: 0 - 0.3 volt
When the SET switch is ON: 2.0 - 2.8 volts
When the RESUME switch is ON: 3.3 - 4.1 volts
When the CANCEL switch is ON: 0.8 - 1.5 volts
DIAGNOSIS CODE SET CONDITIONS
If the auto-cruise control switch is operated, this diagnosis code will be set when the
engine-ECU terminal voltage is different from the standard value.
POSSIBLE CAUSES
Malfunction of the auto-cruise control switch.
Malfunction of the clock spring.
Damaged harness or connector.
Malfunction of the engine-ECU.
DIAGNOSIS
STEP 1. M.U.T.-III data list
Item 1D: Auto-cruise control switch (Refer to data list reference table ).
Q.
Is the check result normal?
Go to Step 14.
Go to Step 2.
STEP 2. Check the auto-cruise control switch.
(1)Remove the air bag module (driver’s side) (Refer to GROUP 52B, Driver’s,
Front Passenger’s Air Bag Module(s) and Clock Spring ).
(2)Check the auto-cruise control switch (Refer to ).
Q.
Is the check result normal?
Go to Step 3.
Replace the auto-cruise control switch (Refer to ),
and install the air bag module (driver’s side) (Refer to GROUP 52B Driver’s,
Front Passenger’s Air Bag Module (s) and Clock Spring ).
Then go to Step 15.
STEP 3. Measure the voltage at auto-cruise control switch connector
C-201.
(1)Connect the negative (-) battery cable.
(2)Turn the ignition switch to the "ON" position and the MAIN switch to the "OFF"
position.
(3)Measure the voltage between connector C-201 terminal No.2 and earth. OK: 4.7-5.0 V (4)Turn the ignition switch to the "LOCK" (OFF) position.
Repair or replace the faulty connector, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 5. Check the harness between engine-ECU connector B-05 terminal
No.52 and the auto-cruise control switch connector C-201 terminal No.2.
(1)Disconnect engine-ECU connector B-05 and measure at the harness connector side.
(2)Measure the continuity between engine-ECU connector B-05 terminal No.52 and earth. (3)Connect engine-ECU connector B-05.
Q.
Is the measured continuity open circuit?
Install the air bag module (driver’s side) (Refer to GROUP 52B, Driver’s,
Front Passenger’s Air Bag Module(s) and Clock Spring ).
Then go to Step 14.
Go to Step 6.
STEP 6. Connectors check: C-201 auto-cruise control switch connector,
C-202 and C-204 clock spring connectors
Q.
Is the check result normal?
Go to Step 7.
Repair or replace the faulty connector, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 7. Check the clock spring.
Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and
Clock Spring .
Q.
Is the check result normal?
Go to Step 8.
Replace the clock spring and install the air bag module (driver’s side)
(Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 8. Check the harness between engine-ECU connector B-05 terminal
No.52 and the auto-cruise control switch connector C-201 terminal No.2.
Q.
Is the check result normal?
It can be assumed that this malfunction is intermittent, and install the air bag
module (driver’s side) (Refer to GROUP 52B, Driver’s, Front Passenger’s
Air Bag Module(s) and Clock Spring ). Then go to Step 15
.
Repair the damaged harness wire, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 9. Measure the voltage at auto-cruise control switch connector
C-201.
(1)Turn the ignition switch to the "ON" position and the MAIN switch to the "ON" position.
(2)Measure the voltage between connector C-201 terminal No.3 and earth. OK: 0.3 V or less
(3)Turn the MAIN switch to the "OFF" position and the ignition switch to the "LOCK"
(OFF) position.
Q.
Is the check result normal?
Go to Step 13.
Go to Step 10.
STEP 10. Connectors check: B-06 engine-ECU connector, C-38 intermediate
connector, C-201 auto-cruise control switch connector, C-202 and C-204 clock spring connectors
Q.
Is the check result normal?
Go to Step 11.
Repair or replace the faulty connector, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 11. Check the clock spring.
Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and
Clock Spring .
Q.
Is the check result normal?
Go to Step 12.
Replace the clock spring and install the air bag module (driver’s side)
(Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 12. Check the harness between engine-ECU connector B-06 terminal
No.128 and the auto-cruise control switch connector C-201 terminal No.3.
Q.
Is the check result normal?
It can be assumed that this malfunction is intermittent, and install the air bag
module (driver’s side) (Refer to GROUP 52B, Driver’s, Front Passenger’s
Air Bag Module(s) and Clock Spring ). Then go to Step 15
.
Repair the damaged harness wire, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 13. Connector check: C-201 auto-cruise control switch connector
Q.
Is the check result normal?
Go to Step 14.
Repair or replace the faulty connector, and install the air bag module (driver’s
side) (Refer to GROUP 52B, Driver’s, Front Passenger’s Air Bag Module(s) and Clock
Spring ). Then go to Step 15.
STEP 14. Check the M.U.T.-III diagnosis code.
Q.
Is M.U.T.-III diagnosis code P0578 or P0579 set?
Replace the engine-ECU (Refer to GROUP 13A, Engine-ECU ).
Then go to Step 15.
It can be assumed that this malfunction is intermittent.
STEP 15. Check the M.U.T.-III diagnosis code.
Q.
Is M.U.T.-III diagnosis codeP0578 or P0579 set?
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Go to Step 14.
Go to Step 2.)
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