DTC Troubleshooting

DIAGNOSTIC INFORMATION AND PROCEDURES REFERENCE CHART

Step	Action	YES	NO
1	Was "Engine and Emission Control System Check" performed?	Go to Step 2.	Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2	Wire harness check Turn ignition switch to OFF position. Check for proper terminal connection to radiator cooling fan relay (No. 1, No. 2 or No. 3) and ECM connectors. If connections are OK, recheck DTC. Is DTC P0480 or P0481 detected again?	Go to Step 3.	Intermittent trouble.
3	Circuit fuse check Check "RDTR" fuse (1) in fuse box No. 1 with ignition switch turned OFF. Is "RDTR" fuse in good condition?	Go to Step 4.	Check for short in circuits connected to this fuse.
4	Radiator cooling fan drive circuit voltage check Turn ignition switch to OFF position. Disconnect connectors from ECM. Turn ignition switch ON position. Check that radiator cooling fan relay (No. 1, No. 2 or No. 3) drive circuit voltage is battery voltage between ECM connector and vehicle body ground. Is it in good condition?	Substitute a known-good ECM and recheck DTC	Go to Step 5.
5	Radiator cooling fan drive circuit voltage check Turn ignition switch to OFF position. Remove radiator cooling fan relay No. 1 (1), No. 2 (2) or No. 3 (3). Turn ignition switch ON position. Check that radiator cooling fan relay (No. 1, No. 2 or No. 3) power supply voltage is battery voltage between radiator cooling fan relay (No. 1, No. 2 or No. 3) connector and vehicle body ground. Is it in good condition?	Go to Step 6.	Repair or replace power supply circuit of radiator cooling fan relay (No. 1, No. 2 or No. 3).
6	Radiator cooling fan relay check Check radiator cooling fan relay No. 1, No. 2 or No. 3 for operation. Refer to RADIATOR COOLING FAN RELAY INSPECTION . Is it in good condition?	Repair or replace drive circuit of radiator cooling fan relay (No. 1, No. 2 or No. 3). If circuit is OK, substitute a known-good ECM and recheck DTC	Replace radiator cooling fan relay No. 1, No. 2 or No. 3.