2003 LEXUS LS430 Ecm

Fig. 53: DTC P1615 And U1101 Problem Symptom Diagnostic Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, one or more DTCs in the CAN communication system
is/are output if there are any malfunctions in the communication circuit.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)
CIRCUIT DESCRIPTION
The ECM receives signals from each sensor and ECU, then sends signals such as the A/T signal, cruise control
<005200530048005500440057004c0052005100030056004c004a00510044004f000f0003004f0052005a0003005600530048004800470003005200530048005500440057004c0052005100030056004c004a00510044004f000f0003004500550044004e00
480003004600520051005700550052004f0003005200530048[ration signal and laser light emission prohibiting
signal, etc. to the distance control ECU.
<0037004b004800030028002600300003004c005600030057004b0048000300520051004f005c000300460052005000530052005100480051005700030057004b004400570003004b0044005600030044000300490058005100460057004c00520051000300
57005200030055004800460052005500470003004400510047[ output the DTCs in the dynamic radar cruise
control system. Therefore if the distance control ECU detects a communication error from the ECM, it sends the
malfunction signal back to the ECM.
Fig. 54: DTC P1616 And U0100 Problem Symptom Diagnostic Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication
circuit, one or more DTCs in the CAN communication system is/are output.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)
CIRCUIT DESCRIPTION
In the dynamic radar cruise control system, the ECM and the distance control ECU communicate with one
another to control the system based on some designation information. If the designation information of the
ECM and distance control ECU is different from each other, this DTC is recorded.
DTC P1617 PROBLEM SYMPTOM DIAGNOSTIC
INSPECTION PROCEDURE
1.CONFIRM THE DESIGNATION INFORMATION
a. If this DTC is output, confirm the designation information by following the procedures below.
1. Turn the ignition switch to the ON position.
2. Push the ON-OFF button of the cruise main switch on.
3. With the brake pedal depressed, push the cruise control main switch to RES/ACC 3 times
within 3 seconds. Check that the VSC buzzer sounds at this time.
If the light control switch is turned on by mistake, readjust the optical axis (refer to
ADJUSTMENT
for optical axis adjustment).
DTC NO.DTC Detecting ConditionTrouble Area
P1617While the dynamic radar cruise control is either
preparing for
operation or operating, if the designation signal from
the ECM
and the designation return signal from the distance
control
ECU do not match one another for a certain amount
of time or
more, the ECM records this trouble codeCruise control ECU (Distance
control ECU)

4. Clear the DTC and then recheck for DTCs.
OK: DTC is not output.
HINT:
If DTC P1617 is still output after performing the above procedures, replace the distance control
ECU.
If the DTC P1617 is still output after replacing the distance control ECU, replace the ECM.
NG: REPLACE CRUISE CONTROL ECU ASSY (SEE REPLACEMENT
)
OK: SYSTEM OK
CIRCUIT DESCRIPTION
The skid control ECU sends signals such as cruise control cancel demand signal, brake operation demand
response signal from the ECM, etc. to the ECM when the dynamic radar cruise control system is in operation.
Fig. 55: DTC P1630 And U0122 Problem Symptom Diagnostic Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication
circuit, one or more DTCs in the CAN communication system is/are output.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)

CIRCUIT DESCRIPTION
The ECM sends signals such as A/T information signal, dynamic radar cruise control operation signal, brake
operation demand signal, buzzer operation demand signal and low speed mode signal, etc. to the skid control
ECU when the dynamic radar cruise control is in operation.
<0037004b004800030028002600300003004c005600030057004b0048000300520051004f005c000300460052005000530052005100480051005700030057004b004400570003004b0044005600030044000300490058005100460057004c00520051000300
57005200030055004800460052005500470003004400510047[ output the DTCs in the dynamic radar cruise
control system. Therefore if the skid control ECU detects a communication error from the ECM, it sends the
malfunction signal back to the ECM.
Fig. 56: DTC P1631 And U0100 Problem Symptom Diagnostic Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
HINT:
This circuit uses CAN for communication. Therefore, if there are any malfunctions in the communication
circuit, one or more DTCs in the CAN communication system is/are output.
1.GO TO CAN COMMUNICATION SYSTEM (SEE PRECAUTION
)
CIRCUIT DESCRIPTION
The ABS & traction actuator assy (skid control ECU) receives the alarm demand signal from the ECM and
operates the skid control buzzer.
The buzzer sounds to warn that the distance between the vehicle in front and
your own vehicle is shortening.

Fig. 77: Disconnecting Millimeter Wave Radar Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: Go To Next Step.
2.CHECK WIRE HARNESS AND CONNECTOR
a. Disconnect the ECM E3 connector.
b. Measure the resistance according to the value(s) in the table below.
Standard:
MILLIMETER WAVE RADAR SENSOR TERMINALS RESISTANCE SPECIFICATION
Tester connectionConditionSpecified value
M7-1 (LGND) - E3-29 (LGND)AlwaysBelow 1 ohms

Fig. 79: Disconnecting ECM E3 Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
3.CHECK WIRE HARNESS AND CONNECTOR (MILLIMETER WAVE RADAR SENSOR -
DISTANCE CONTROL ECU)
a. Disconnect the cruise control ECU (distance control ECU) connector.
b. Measure the resistance according to the value(s) in the table below.
Standard:
MILLIMETER WAVE RADAR SENSOR AND DISTANCE CONTROL ECU TERMINALS
RESISTANCE
Tester connectionConditionSpecified value
D2-13 (IGB) - M7-5 (IGB)AlwaysBelow 1 ohms
D2-13 (IGB) - Body groundAlways10 kohms or higher

Fig. 81: Disconnecting Cruise Control ECU (Distance Control ECU) Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
CIRCUIT DESCRIPTION
The cruise control main switch operates eight functions: SET, COAST, TAP-DOWN, RESUME, ACCEL,
TAP-UP, CANCEL and MODE. The SET, TAP-DOWN and COAST functions, and the RESUME, TAP-UP
and ACCEL functions are operated with the same switch. The cruise control main switch is an automatic return
type switch which turns on only while operating it in each arrow direction and turns off after releasing it. The
internal contact point of the cruise control main switch is turned on with the switch operation. The ECM then
reads the resistance value that has been changed by the switch operation to control MODE, SET, COAST,
RESUME, ACCEL and CANCEL.

Fig. 83: Identifying Cruise Control Main Switch Position
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
CC (ECM):
DATA LIST (CC (ECM))
OK: When cruise control main switch operation is performed, the standard values will be above.
Item
Measurement Item / Display
(Range)
Normal ConditionDiagnostic Note
MAI NSW
(MAIN)Main SW signal (Main CPU) /
ON or OFFON: Main SW ON (Pushed
on) OFF: Main SW OFF
(Pushed off)-
MAI NSW (SUB)Main SW signal (Sub CPU) /
ON or OFFON: Main SW ON (Pushed
on)OFF: Main SW OFF
(Pushed off)
CANCEL SWCANCEL SW signal / ON or
OFFON: CANCEL SW ON OFF:
CANCEL SW OFF-
SET/COAST SWSET/COAST SW signal / ON or
OFFON: SET/COAST SW ON
OFF: SET/COAST SW OFF-
RES/ACC SWRES/ACC SW signal / ON or
OFFON: RES/ACC SW ON
OFF: RES/ACC OFF-