Hi. I'm new to this site. I have changed out the heater core and blend door on my 2001 f150 supercrew. After reinstalling the dash, everything works but the low beam headlamps. Any ideas as to what went wrong?

 

Did you pull the dash? How did you address the steering column? Was it dropped or removed?

 

Yes, I pulled the dash and I dropped the steering column, I didn't remove it.

 

Assuming no autolamps or DRL, the basic headlight circuit is:

The headlight switch feeds the MFS on the column via a RED/YELLOW wire. The output of the MFS is either the HIGH BEAM circuit on a GRAY/ORANGE wire that feeds fuse F16 in the CJB or the LOW BEAM circuit via another RED/YELLOW wire that feeds fuses F26, F28, and, if equipped with fogs, F27 in the CJB.

Check those circuits.

 

Will do. Will take some time to get back here. I don't have the steering column covers off yet. Hope to get started this morning.

 

No autolamps or DRL. Two red/yellow wires from the back of MFS are hot when I turn on the headlamp switch. Fuses 26 & 28 are good.

 

Check for power at F26 & F28 when the low-beams should be on, that's what's important.

 

No power to the fuses when the switch is on.

 

Then you have an open circuit between the output of the MFS and the fuse panel.

The schematics show a connector that is supposed to have a jumpered plug in it where the DRL relay block would have been if the truck had been equipped with DRL. The connector is round and has 8-pin connector (only 6 are used) and is located somewhere up behind the glovebox area. I'd look for that first as anything else would involve a physically damaged wire somewhere in the path from the MFS to that connector and back again to the fuse box.

 

Ok, I will check for it. Do you think I will need to remove the passenger side airbag?

 

Don't know, never had to dig around up in there on a half ton. Maybe someone else can chime in with hands-on experience.

 

I found it. It's located under the access panel that is on top of the dash. Just had to snap off the access panel and there it is. I didn't have the harness plugs connected all the way. I feel like a fool but I'm glad it wasn't anything more serious. Lowbeams work now. Thank you so much for your help.

 

Sweet! Glad to help!