I'm not sure I understand? Are you saying the dimmer switch switches from bright to dim by itself? Are you talking about daytime running lamps? I have seen a faulty battery and or cable cause the headlamp intensity to brighten and dim. Any faulty electrical circuit might cause that. I can't say for sure, one way or the other, that your fuel pump module is the problem? Give me a minute, I'll find the diagram.
Any applicable trouble codes? Has any work been done on the vehicle lately?
Please consider a to help us answer more questions.
Tuesday, November 20th, 2012 AT 5:33 PM