Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
- Perform SET/COAST, RES/ACC and CANCEL switch input signal checks. See STEPS 1-3 of Cruise Control Input Signal Check. See Figure. If SET/COAST, RES/ACC or CANCEL input signals are not as specified, go to next step. If input signals are as specified, no problem is indicated at this time. Fault may be intermittent, go to step 6.
- Turn ignition off. Remove cruise control ECU with 16-pin electrical harness connector attached. See Figure. Turn ignition on. Using a DVOM, backprobe between ground and cruise control ECU 16-pin electrical harness connector terminal No. 10 (White wire) with switch in specified positions. See CRUISE CONTROL ECU VOLTAGES table. If voltage is as specified, go to next step. If voltage is not as specified, fault may be intermittent, go to step 6.CRUISE CONTROL ECU VOLTAGES
Switch Position Volts Off 10-16 On Less Than 1 RES/ACC 4.7-7.7 SET/COAST 2.6-4.2 - Turn ignition off. Disable air bag system. See AIR BAG RESTRAINT SYSTEMS
article. Remove steering wheel center pad (air bag module) and disconnect cruise control switch Black 6-pin electrical harness connector. Measure resistance between cruise control switch terminals No. 4 and 5 with switch in specified positions. See Fig 1. See CRUISE CONTROL SWITCH RESISTANCE table. If resistance is as specified, go to next step. If resistance is not as specified, replace cruise control switch. See CRUISE CONTROL SWITCH under REMOVAL & INSTALLATION. After repairs, perform confirmation test. See CONFIRMATION TEST .CRUISE CONTROL SWITCH RESISTANCE
Switch Position Ohms Off Infinity On Continuity RES/ACC 240 SET/COAST 630 - Turn ignition off. Disconnect cruise control ECU 16-pin electrical harness connector and cruise control switch Black 6-pin electrical harness connector. Using a DVOM, check for open and short circuit conditions in White/Blue wire between cruise control ECU 16-pin electrical harness connector terminal No. 1 and cruise control switch Black 6-pin electrical harness connector terminal No. 3. See Figure. Check White wire between cruise control ECU 16-pin electrical harness connector terminal No. 10 and cruise control switch Black 6-pin electrical harness connector terminal No. 5. Also check White/Black wire between cruise control ECU 16-pin electrical harness connector terminal No. 16 and cruise control switch Black 6-pin electrical harness connector terminal No. 4. If wires, harnesses and connectors are okay, go to next step. If wires, harnesses and connectors are not okay, repair fault as required. See CRUISE CONTROL in SYSTEM WIRING DIAGRAMS article. After repairs, perform confirmation test. See CONFIRMATION TEST .
- Repeat step 1. If SET/COAST, RES/ACC or CANCEL input signals are still not as specified, go to next step. If input signals are as specified, no problem is indicated at this time. Fault may be intermittent, go to next step.
- Turn ignition off. Disconnect cruise control ECU 16-pin electrical harness connector. Using DVOM, check cruise control ECU ground circuit. See CRUISE CONTROL in SYSTEM WIRING DIAGRAMS article. If ground circuit is faulty, repair and retest system. If ground circuit is okay, substitute original cruise control ECU with a known-good unit and recheck system operation. If system operates properly, original cruise control ECU was defective. If system still does not operate properly, perform cruise control ECU pin voltage check. See PIN VOLTAGE TESTS . Check wiring harness and electrical connectors for an intermittent problem. Repair wiring harnesses or connectors as necessary. See CRUISE CONTROL in SYSTEM WIRING DIAGRAMS article. If voltage values, harnesses and connectors are okay, replace cruise control ECU. See CRUISE CONTROL ELECTRONIC CONTROL UNIT under REMOVAL & INSTALLATION. After repairs, perform confirmation test. See CONFIRMATION TEST .