TEST 2: Making Sure The Headlight Switch Is Getting Power

Making Sure The Headlight Switch Is Getting Power. How To Test A No Park-Lamps Problem (1997, 1998 F150, F250, And Expedition)

So far, you've checked fuse #7 (of the under-hood fuse/relay box) and it's not blown. Now, we're gonna' make sure that power is present at terminal #5 of the grey headlight switch connector.

The wire that feeds battery power to female terminal #5 (of the grey connector) is the tan with white stripe (TAN/WHT) wire.

By the way, the TAN/WHT wire gets its power from the #7 fuse (of the under-hood fuse/relay box).

NOTE: All of the test steps in this tutorial assume that you have removed the headlight switch from its place on the instrument panel.

OK, this is what you need to do:

  1. 1

    Place you multimeter in Volt DC mode

  2. 2

    Check that terminal #5, of the grey connector, has 10 to 12 Volts DC.

    The wire that feeds battery power to terminal #5 is the TAN/WHT wire.

  3. 3

    Battery power should be present with the key on or the key off.

Let's interpret your test results:

CASE 1: 10 to 12 Volts are present. So far so good, since this is the correct and expected test result.

Your next step is to go to: TEST 3: Jumpering The Park-Lamps Circuit.

CASE 2: Battery power IS NOT present. This usually means that fuse #7, of the engine compartment fuse box, is blown. But you have already checked the fuse (in TEST 1). So this usually means that there's and open in this circuit.

Although it's beyond the scope of this tutorial to test this problem, your next step is to get a wiring diagram and test the continuity of this power circuit between the connector and the fuse box and repair the open-circuit.

TEST 3: Jumpering The Park-Lamps Circuit

Jumpering The Park-Lamps Circuit. How To Test A No Park-Lamps Problem (1997, 1998 F150, F250, And Expedition)

In this test section we're gonna' jumper female terminals 4 and 5 of the grey headlight switch connector.

Once the jumper wire is installed, and if the circuits between the park-lamps and the connector are OK, the park-lamps should come on.

If the park-lamps do not come on, then we can assume that there's an electrical problem between the connector and the park-lamps.

If the park-lamps do light up, then we can move on to the last test (TEST 4).

OK, this is what you need to do:

  1. 1

    Locate female terminals #4 and #5 of the grey headlight switch connector (see photo above).

  2. 2

    Using a jumper wire, jumper terminals 4 and 5.

  3. 3

    The park-lamps should come on as soon as you jumper the two terminals of the headlight switch's connector.

    NOTE: The park-lamps should come on whether you have the key in the ON or OFF position.

Let's take a look at what your test results mean:

CASE 1: The park-lamps turned on. So far so good, since this is the correct and expected test result. This test result also tells you that there aren't any electrical wiring problems between the connector and the park-lamps.

The next step is to test the continuity between pins 4 and 5 of the headlight switch itself. Go to: TEST 4: Testing The Continuity Of The Park-Lamps Circuit.

CASE 2: The park-lamps DID NOT turn on. This usually indicates a problem in the wiring between the connector and the park-lamps.

Your next step is to check the continuity of the BRN wire between the connector and the park-lamps and repair the open-circuit.