Dome Light not working

PPRINCE72

MEMBER
2004 FORD F-150
5.4L
V8
4WD
AUTOMATIC
226,000 MILES

My symptoms are; when driving sometimes parked for hours and the dome lights and rear box lights come on, no door ajar light comes on. Last time driving it turned on and turned the switch on and off and light went off. Today a service guy came and said my dome lights were on. Looked hour later and they were off by them self. Question is, do you think it is the dimmer switch? I'm guessing it is. Thank you!

Wednesday, November 17th, 2021 AT 2:44 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,077 POSTS

Hi,

This could be the switch or the battery saver relay. I attached the wiring schematic below for your reference. I had to cut it in half to make it readable for you, but I did overlap them.

When this happens, I want you to try something. In the central junction box, there are two fuses that are relevant for this, fuses 6 and 24. When the lights turn on by themselves, remove one fuse at a time to see which one causes the light to turn off.

Also, relay 304 in the central junction box (in vehicle) can also be bad. If there is another relay with the same part number, switch them to see if the problem stops. If there isn't, here is a link that explains how to test the relay. Pic 3 shows the relay I'm referring to.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find.

Take care,

Joe

See pics below.

Images (Click to make bigger)