TEST 4: Testing The HI Blower Speed Circuit
If you take a look at the blower motor circuit diagram, of your 2.5L Ford Ranger (Mazda B2500), you'll notice that the HI blower speed circuit bypasses the blower resistor completely.
This means, that we're going to need to probe the blower motor electrical connector with our 12 Volt test light and NOT the blower resistor block's connector (like in the previous three tests).
These are the test steps:
Place the AC/Heater Control Panel's vent selection control knob on any selection but OFF.
NOTE: The blower resistor and the blower motor must be disconnected from their electrical connectors.
Connect the 12 Volt test light's alligator clip to the positive (+) battery terminal of your Ford Ranger's battery.
Select blower motor speed HI on the AC/Heater Control Panel.
Probe the blower motor female terminal identified with the #2 with the metallic point of your 12 Volt test light.
Female terminal #2 has an orange with black stripe (ORG/BLK) wire connecting to it.
The 12 Volt test light should come on if the HI circuit is OK.
Let's examine your test result:
CASE 1: The 12 Volt test light turned on. This is the correct test result and lets you know that the blower motor switch's HI circuit is working correctly.
If the blower motor switch passed all of the previous tests (TEST 1, TEST 2, TEST 3), then you can conclude that the blower motor switch is not defective on your 2.5L Ford Ranger (Mazda B2500).
CASE 2: The 12 Volt test light DID NOT turn on. This test result lets you know that the blower motor switch is defective and needs to be replaced.
Identifying The Vent Control Switch Selections
More 2.5L Ford Tutorials
You can find a complete list of tutorials here: Ford 2.5L Index Of Articles.
Here's a sample of the tutorials you'll find there:
- Ignition System Circuit Diagram (1998-2001 2.5L Ford Ranger).
- Oxygen Sensor Circuit Diagram (1998-2001 2.5L Ford Ranger).
- How To Test The Front O2 Sensor Heater (1998-2001 2.5L Ford Ranger).
- Rear O2 Sensor Heater Test (1998-2001 2.5L Ford Ranger).
If this info really saved the day, buy me a beer!