Page 1376 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-45
STEP 15. Measure the terminal voltage at Engine ECU
connector B-21.
(1) Disconnect all the connectors from the Engine ECU.
(2) Connect special tool MB992044 between the Engine ECU
and the body-side harness connector.
(3) Turn the ignition switch to the "ON" position.
(4) Measure the terminal voltage between special tool 94-pin
connector terminal 21 (Engine ECU connector B-21
terminal 21) and ground.
When the brake pedal is depressed, the voltage should
measure battery positive voltage (approximately 12
volts).
When the brake pedal is released, the voltage should
measure 1 volt or less.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
(6) Disconnect special tool MB992044 between the Engine
ECU and the body-side harness connector.
(7) Reconnect all the connectors to the Engine ECU.
Q: Is the measured voltage battery positive voltage
(approximately 12 volts) when the brake pedal is
depressed and 1 volt or less when the brake pedal is
released?
YES : Go to Step 20.
NO : Go to Step 16.
STEP 16. Check the stoplamp switch.
(1) Remove the stoplamp switch. (Refer to GROUP 35A, Brake
Pedal P.35A-24).
(2) Connect an ohmmeter to the stoplamp switch between
terminals 3 and 4.
(3) Check for continuity between the terminals when the
plunger of the stoplamp switch is pushed in and when it is
released.
(4) The stoplamp switch is operating properly if the circuit is
open between terminals 3 and 4 when the plunger is
pushed in, and if resistance value is less than 2 ohms
between terminals 3 and 4 when the plunger is released.
Q: Is the stoplamp switch operating properly?
YES : Install the stoplamp switch. (Refer to GROUP 35A,
Brake Pedal P.35A-24). Then go to Step 17.
NO : Replace the stoplamp switch. (Refer to GROUP 35A,
Brake Pedal P.35A-24). Then go to Step 22.
Page 1377 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-46
STEP 17. Check Engine ECU connector B-21 and stoplamp
switch connector C-30 for loose, corroded or damaged
terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES : Go to Step 18.
NO : Repair or replace the damaged components. (Refer to
GROUP 00E, Harness Connector Inspection
P.00E-2). Then go to Step 22.
Page 1378 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-47
STEP 18. Check the harness wire between Engine ECU
connector B-21 terminal 21 and stoplamp switch
connector C-30 terminal 3 for damage.
Q: Is the harness wire in good condition?
YES : Go to Step 19.
NO : Repair the damaged harness wire if possible, or as
recommended, replace complete harness. Then go to
Step 22.
STEP 19. Check the harness wire between stoplamp
switch connector C-30 terminal 4 and ground for damage.
Q: Is the harness wire in good condition?
YES : Go to Step 20.
NO : Repair the damaged harness wire if possible, or as
recommended, replace complete harness. Then go to
Step 22.
Page 1379 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-48
STEP 20. Using Diagnostic Tool MB991958, check data list
item 89: Normally closed Brake Switch.
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958.
(1) Connect Diagnostic Tool MB991958 to the data link
connector. (Refer to P.17-11).
(2) Turn the ignition switch to the "ON" position.
(3) Set Diagnostic Tool MB991958 to data reading mode for
auto-cruise control system. (Refer to P.17-11).
Item 89, Normally closed Brake Switch.
When the brake pedal is depressed, the display on
Diagnostic Tool MB991958 should be "ON".
When the brake pedal is released, the display on
Diagnostic Tool MB991958 should be "OFF".
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.
Q: Is the switch operating properly?
YES : Go to Step 21.
NO : Replace the Engine ECU. [Refer to GROUP 13A,
Engine ECU 13A-675] . Then go to Step 22.
STEP 21. Using Diagnostic Tool MB991958, read the
diagnostic trouble codes.
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958.
(1) Connect Diagnostic Tool MB991958 to the data link
connector. (Refer to P.17-11).
(2) Turn the ignition switch to the "ON" position.
(3) Set Diagnostic Tool MB991958 to read the diagnostic
trouble codes. (Refer to P.17-11).
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.
Q: Is DTC 1571 set?
YES : Replace the Engine ECU.[Refer to GROUP 13A,
Engine ECU 13A-675] . Then go to Step 22.
NO : It can be assumed that this malfunction is intermittent.
(Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunction P.00-14).
Page 1381 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-50
DTC 1574: Engine ECU and Its Related Components
.
DTC SET CONDITIONS
This DTC is set when there is a failure in the Engine
ECU and its related components.
.
TROUBLESHOOTING HINTS (THE MOST
LIKELY CAUSES FOR THIS CODE TO BE
SET ARE:)
Malfunction of the MPI system.
Malfunction of the A/T system.
Malfunction of the Engine ECU.
Circuit drawings
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
Refer to component locations GROUP-70
DIAGNOSIS
Required Special Tools:
MB991958: Diagnostic Tool (MUT-III Sub Assembly)
MB991824: V.C.I.
MB991827: MUT-III USB Cable
MB991910: MUT-III Main Harness A
STEP 1. Using Diagnostic Tool MB991958, read the MPI
system diagnostic trouble code.
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958.
(1) Connect Diagnostic Tool MB991958 to the data link
connector. (Refer to P.17-11).
(2) Turn the ignition switch to the "ON" position.
(3) Check for MPI system diagnostic trouble code. (Refer to
GROUP 13A, MPI Diagnosis
Diagnostic Function How
to Read and Erase Diagnostic Trouble Code 13A-6) .
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.
Q: Is any DTC set?
YES : Diagnose the MPI system. (Refer to GROUP 13A,
MPI Diagnosis
Diagnostic Trouble Code Chart
13A-17) . Then go to Step 4.
NO : Go to Step 2.
Page 1382 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-51
STEP 2. Using Diagnostic Tool MB991958, read the A/T
system diagnostic trouble code.
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958.
(1) Connect Diagnostic Tool MB991958 to the data link
connector. (Refer to P.17-11).
(2) Turn the ignition switch to the "ON" position.
(3) Check for A/T system diagnostic trouble code. (Refer to
GROUP 23A, A/T Diagnosis
Diagnostic Function How
to Read and Erase Diagnostic Trouble Code P.23A-13).
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.
Q: Is any DTC set?
YES : Diagnose the A/T system. (Refer to GROUP 23A, A/T
Diagnosis
Diagnostic Trouble Code Chart
P.23A-34). Then go to Step 4.
NO : Go to Step 3.
STEP 3. Using Diagnostic Tool MB991958, read the
auto-cruise control system diagnostic trouble code.
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958.
(1) Connect Diagnostic Tool MB991958 to the data link
connector. (Refer to P.17-11).
(2) Turn the ignition switch to the "ON" position.
(3) Use Diagnostic Tool MB991958 to read the auto-cruise
control system diagnostic trouble codes. (Refer to P.17-11).
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.
Q: Is DTC 1574 set?
YES : Replace the Engine ECU.[Refer to GROUP 13A,
Engine ECU 13A-675] . Then go to Step 4.
NO : It can be assumed that this malfunction is intermittent.
(Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunction P.00-14).
Page 1384 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-53
SYMPTOM CHARTM1172002300366
NOTE: If engine speed reaches and exceeds 6000
r/min the Auto Cruise Control System will be can-
celled automatically.SYMPTOM INSPECTION
PROCEDURE NO.REFERENCE
PA G E
Communication with
Diagnostic Tool is
not possibleCommunication with all systems is
impossible- Group 13A, MPI
Diagnosis
Symptom
Procedures
Inspection
Procedure 1
13A-539 .
Communication with the Engine ECU only
is impossible- Group 13A, MPI
Diagnosis
Symptom
Procedures
Inspection
Procedure 2
13A-541 .
Auto-cruise control
system is not
cancelled.When brake pedal is depressed 1
P.17-54
When selector lever is moved to "N" range 2
P.17-54
When "CANCEL" switch is turned ON 3
P.17-55
When clutch pedal is depressed 4
P.17-55
Auto-cruise control system cannot be set. 5
P.17-56
Hunting (repeated acceleration and deceleration) occurs at the
set vehicle speed.6
P.17-60
When "CRUISE" (MAIN) switch is turned "ON", "CRUISE"
indicator lamp inside combination meter does not illuminate.
(However, auto-cruise control system is normal).7
P.17-62
Page 1385 of 1500
AUTO-CRUISE CONTROL
ENGINE AND EMISSION CONTROL17-54
SYMPTOM PROCEDURES
INSPECTION PROCEDURE 1: When the Brake Pedal is Depressed, Auto-cruise Control System is not
Cancelled.
.
COMMENT
The stoplamp switch circuit is suspected.
.
TROUBLESHOOTING HINTS (THE MOST
LIKELY CAUSES FOR THIS CASE:)
Malfunction of the stoplamp switch.
Damaged harness or connector.
Malfunction of the Engine ECU.
Circuit drawings
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
Refer to component locations GROUP-70
DIAGNOSIS
Refer to P.17-35, Diagnostic Trouble Code Procedures DTC
22: Stoplamp Switch System.
INSPECTION PROCEDURE 2: When the Selector Lever is Moved to "N" Range, Auto-cruise Control
System is not Cancelled.
.
COMMENT
The transmission inhibitor switch circuit is suspected.
.
TROUBLESHOOTING HINTS (THE MOST
LIKELY CAUSES FOR THIS CASE:)
Malfunction of the transmission inhibitor switch.
Damaged harness or connector.
Malfunction of the Engine ECU.
Malfunction of A/T ECU.
Circuit drawings
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
Refer to component locations GROUP-70
DIAGNOSIS
Refer to GROUP 23A, A/T Diagnosis Diagnostic Trouble
Code Procedures
DTC 0705: Transmission Inhibitor Switch
System (Open/short Circuit) P.23A-97.
