System Operation Check

WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

Trouble shooting of a cruise control system complaint begins with verification of the customer problem. Perform the Customer Problem Analysis Check (Cruise Control System). See Fig 1.
Check and clear the DTC. See PRE-CHECK under SELF-DIAGNOSTIC SYSTEM.
- If a DTC does not output, check that there is no abnormality in the communication system by inspecting the communication function of the body multiplex communication system with a hand-held tester. If there are code outputs (ECU unconnected and the communication line abnormal), see appropriate MULTIPLEX COMMUNICATION SYSTEM - ES 300 article in COMMUNICATION DEVICES.
- If a DTC is output, go to next step.
Perform a symptom simulation as follows:
- Check the battery positive voltage (10-14 volts with engine stopped).
- Visually check the wire harness, connectors and fuses for open and short, etc.
- Warm up the engine to the normal operating temperature.
- Confirm the problem symptoms and conditions and check for DTC(s). If DTC(s) are set, refer to DTC table. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . Perform appropriate circuit inspection. See DIAGNOSTIC TESTS and/or SYSTEM TESTS . After repairs, go to step 6. If no DTC is set, go to next step.

When no code is output (symptom check and simulation not possible), refer to CRUISE CONTROL PROBLEM SYMPTOMS table. Then, go to next step.

CRUISE CONTROL PROBLEM SYMPTOMS

Symptom

Suspected Area ⁽¹⁾

Main Switch Cannot Be Turned ON (Cruise Indicator Light In Combination Meter Is Not Lit)

⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾⁽⁶⁾

Vehicle Speed Setting Cannot Be Done (Although Indicator Light In Combination Meter Is Lit When The Main Switch Is Turned ON, They Go Off When Vehicle Speed Is Set)

⁽²⁾⁽³⁾⁽⁴⁾⁽⁶⁾

Setting Cannot Be Done (Indicator Light In Combination Meter Is Lit When The Main Switch Is Turned ON & They Remain ON While Setting)

⁽²⁾⁽³⁾⁽⁷⁾⁽⁸⁾⁽⁴⁾⁽⁹⁾⁽⁶⁾

While The Vehicle Is Driving With Cruise Control, The Set Control Is Canceled (Indicator Light & CRUISE Remain ON)

⁽²⁾⁽³⁾⁽¹⁰⁾⁽⁷⁾⁽⁵⁾⁽⁸⁾⁽⁴⁾⁽⁶⁾

Hunting (Speed Is Not Constant)

⁽¹⁰⁾⁽¹¹⁾⁽⁶⁾

Setting Cannot Be Cancelled (When Coast, Acceleration, Resume, Set Speed Change & Control Switch Are Operated)

⁽²⁾⁽³⁾⁽⁴⁾⁽⁶⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the cruise control switch circuit. See CRUISE CONTROL SWITCH CIRCUIT under SYSTEM TESTS.

⁽³⁾	Check spiral cable. See AIR BAG RESTRAINT SYSTEMS article.

⁽⁴⁾	Inspect the wire harness and repair or replace if necessary.

⁽⁵⁾	Check the cruise main indicator light circuit. See CRUISE MAIN INDICATOR LIGHT CIRCUIT under SYSTEM TESTS.

⁽⁶⁾	Inspect the ECM and replace if necessary. See PIN VOLTAGE CHARTS in ENGINE PERFORMANCE.

⁽⁷⁾	Check the stop light switch circuit. See DTC P1520/52: STOP LIGHT SWITCH CIRCUIT under DIAGNOSTIC TESTS.

⁽⁸⁾	Check the park/neutral position switch circuit. See DTC P1780: PARK/NEUTRAL POSITION SWITCH CIRCUIT MALFUNCTION under DIAGNOSTIC TESTS under DIAGNOSIS - U150E article under AUTOMATIC TRANSMISSIONS in TRANSAXLE/TRANSMISSIONS.

⁽⁹⁾	Check the combination meter system. See INSTRUMENT PANELS article.

⁽¹⁰⁾	Check the vehicle speed sensor circuit. See DTC P0500/21, 23: VEHICLE SPEED SENSOR CIRCUIT under DIAGNOSTIC TESTS.

⁽¹¹⁾	Inspect the malfunction in the speedometer circuit. See INSTRUMENT PANELS article.

Identify problem. Make necessary repairs or replacements. After repairs go to next step.
Perform a confirmation test. See CONFIRMATION TEST (ROAD TEST) under SELF-DIAGNOSTIC SYSTEM.

Fig 1: Customer Problem Analysis Check (Cruise Control System)