1998 F150 LB with a Hi mount stop light w/o the clear cargo box illuminators. It does have the dome/map light combo.
I'd like to upgrade the Hi mount to include the cargo box lighting.

Will the existing wiring harness work? If not, is it possible to pull a feed from the dome light?

Thanks.

 

Not sure if the truck is wired for it already. 99 and older did not have the full harness in them.

The cargo lamps on the CHSML actually is run off the same circuit as the dome lamp.
The wire you are looking for is Black w/ Light Blue stripe
The connector is usually a bit back in the overhead on the '01-03 MY ( think ~ 8" ), so take a look where the connector is for the CHMSL. This is not the bulb connector, but another one for the wiring to it.

If you cannot find it in the CHMSL connector, you can just run straight to the dome lamp, and tap in there. 6' of 14 AWG solid wire should be able to be carefully pushed to the dome lamp. Be careful in doing this, that you do not poke through the headliner. Best to put a small loop back on the end of the wire, so the end you are pushing is round ( bend the wire back on itself with a pair of pliers, make it tight, not open like when mounted on a switch or outlet ).

 

SSCULLY, Thanks again. Good tip on installing the wiring. Exactly what I was looking for.

 

I went to my local salvage yard and picked up a HMSCL and the wiring harness. I took it out so I saw how it's connected.
The plan is to drop the headliner and see what needs to be done to make all the right connections. With a little luck and my USAF electronics training I figure I have a better than 50/50 chance.
Thanks for your help.

 

Dropped the headliner and everything was there to make all the connections. Removed the old one and installed the new one and plugged it in. It pays to be lucky sometimes. Case closed.

 

yup i just did this one today. all that needed to be switched was the wiring.

its great to have cargo lights