DIAGNOSIS AND TESTING -
BLOWER MOTOR RELAY
The front blower motor relay is located in the Intelligent Power Module (IPM), which is in the engine compartment near the battery. See the fuse and relay layout map molded into the inner surface of the IPM cover for front blower motor relay identification and location. Remove the relay from the IPM to perform the following tests:
A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 2. If not OK, replace the faulty relay.
Resistance between terminals 85 and 86 (electromagnet) should be 75 + 5 ohms. If OK, go to Step 3. If not OK, replace the faulty relay.
Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, use a DRBIII(R) scan tool to perform further diagnosis of the relay circuits. If not OK, replace the faulty relay.
Blower motor resistor
The blower motor resistor is connected to the vehicle electrical system through a dedicated take out and connector of the instrument panel wire harness. A second connector receptacle receives the pigtail wire connector from the blower motor. The blower motor resistor has multiple resistor wires, each of which will reduce the current flow through the blower motor to change the blower motor speed. The blower motor switch in the manual heater-A/C control directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor switch in the lowest speed position, the ground path for the motor is applied through all of the resistor wires. Each higher speed selected with the blower motor switch applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed. When the blower motor switch is in the highest speed position, the blower motor resistor wires are bypassed and the blower motor receives a direct path to ground through the blower motor switch. The blower motor resistor may be diagnosed using conventional diagnostic tools and methods
Wednesday, April 29th, 2009 AT 8:29 PM