TEST 6: Testing The Continuity Of The Headlight Circuit
If you've reached this point, you have checked:
- Fuses (TEST 1 and TEST 2).
- That battery power is available at the DK BLU/ORG wire of the black headlight switch connector (TEST 3).
- That the headlights come ON when you jumpered female terminals 4 and 5 of the black headlight switch connector (TEST 4).
In this last test we're gonna' check the continuity of the head-lamp circuit inside the headlight switch.
Continuity is when your digital multimeter registers an Ohms value. No-continuity is when it registers the letters OL.
This is a pretty easy test that's done with your digital multimeter in Ohms mode.
OK, this is what you need to do:
Place your multimeter in Ohms mode.
Turn the headlight switch knob to the ‘headlights on’ position.
Test for continuity between male spade terminals 4 and 5. See the photo above.
If all is OK, your digital multimeter should register continuity. In layman's terms, this means any resistance value that is not an OL reading.
Turn the knob back to it's ‘headlights off’ position.
Your multimeter should now show NO continuity. This is usually represented on the multimeter's screen by the letters OL.
Let's take a look at what your test results mean:
CASE 1: The multimeter DID NOT register continuity. This tells you that the headlight switch is defective and needs to be replaced.
CASE 2: The multimeter registered continuity. This test result tells you that the head-lamps circuit, inside the headlight switch, is OK.
Where To Buy The Headlight Switch And Save
The following links will help you comparison shop for the headlight switch on your 1997-1998 Ford F150, F250, and Expedition:
More 4.6L, 5.4L Ford Diagnostic Tutorials
If this tutorial save the day, then you might be interested in a few others that I have written up. You can check out the rest of the Ford F150, F250, and Expedition tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Clean The Ford MAF Sensor (Ford 4.2L, 4.6L, 5.4L).
- How To Test The Fuel Injectors (1997-2002 4.6L F150).
- How To Test The Ford EGR Valve EGR Vacuum Solenoid, DPFE Sensor.
- How To Test The Ford MAF Sensor (4.2L, 4.6L, 5.4L).
- How To Test The 4.6L, 5.4L Ford Throttle Position Sensor (TPS).
If this info really saved the day, buy me a beer!