Test Description

NOTE: For On-Board Diagnostic (OBD II) System Check procedure, see appropriate SELF-DIAGNOSTICS article.

The following items refer to step(s) in the diagnostic chartS. See Figure -Figure in DIAGNOSTIC CHARTS .

Step No. 4, along with step 5, checks for the ability of the ECM to operate the cooling fans.
Step No. 8, along with step 9, checks for the ability of the ECM to operate the cooling fans in response to A/C pressure readings.
Step No. 16. After confirming battery voltage and the ECM supplying a ground to the coil side of the cooling fan relay "A", by jumpering connector terminals 30 and 87 it will be determined if the relay is at fault or a wiring problem is present.
Step No. 31 checks for the presence of battery voltage to the main cooling fan when the A/C is on. If battery voltage is present and the cooling fans are not operating, the problem is in the ground side of the cooling fan circuit.
Step No. 37. By directly grounding the ECM connector terminals K28 and K12, the main and auxiliary cooling fans should run at high speed.