On our 91.5 truck we've almost got put back together and ready to hit the road again. Started checking all my lights and started at the fuse panel when my gauges and few things wasn't working. Most all my problems were simpily some goob as the PO had shoved fuses in and out of the fuse panel twisting the spades the fuses plug into to where the fuse wasn't getting good contact. Fixed all that and checked for any burned or stripped wires and everything is in great shape. Start checking all my outside and interior lights and EVERYTHING on the truck works flawlessly except for the running lights. I have no running lights including the gauge lights but have headlights,flashers,turn signals,brake lights and everything and all the blubs are brand new. So I checked my fuse for running lights and I had no fire and it only had a 5amp fuse...is that what it takes? Seems a little small in my opinion but put a new 5 back in,no power. So I started testing(with my test light dont have a ohm meter) for power and I have no power at all coming to the fuse panel for the lights. Everything is good and tight,no cut wires at the fuse panel everything is good but no power in the wires to where it runs up into the huge bundle of wires and I don't want to cut into them checking. Looks in my Haynes and Chiltons manuals for wiring diagrams but no go nothing at all for the 91-up BOOOO them books stink. Could yall help me out with any ideas or a good diagram showing the panel and the wires so I can figure out where in the world they go to,to see if I can get power to them. It would be nice to have running lights at night Thanks yall sorry for the long post just wanted to cover the bases so yall wouldn't be just having to guess

 

Same thing happened to me. It was a bad headlight switch. good luck

 

You have a PM. It would help if you filled in your sig, but in this case I am not sure if there is much difference in the wiring of a D or W 250 or 350. There are minor differences in wiring for Canadian or U.S. trucks.

 

I would take a close look at the headlamp switch.

 

Well I replaced the headlight switch and carefully checked all the wires around it for breaks or anything but nothing was out of place. Put it all back together and still no running lights. I traced the pink wire from the fuse panel to the plug in for the headlight switch but wasn't getting any fire to it. Tried to trace the orange wire but it ran way up into the bundle of wires and I couldn't find it. I jumped a wire from another fuse over to the orange side of the fuse for the running lights,plugged the fuse up and ta-da I got running lights. I still can't trace down the orange wire cause now I know it is the hot wire supplying the power.

I'm not a fan at all of cutting into the factory harness but if the lights are only pulling a 3amp fuse from the factory would it be a really bad idea to jump a wire from one of the higher amperage fuse to supply the power to the running lights? I attached pictures with arrows showing what I'm talking about. Don't worry about the wiring looking crappy now I have to re-do some of my wiring and make it look a lot better :P Thanks yall




Jimbo

 

I have a couple of questions. First, is your truck early or late model? When you say running lights, are you referring to the clearance lights? The tan wire runs from the light switch to fuse 14 (the 3 amp). The orange wire powers the dash lamps only (including the ash tray and OD indicator. It does not power the clearance lamps don't run it jumpered. The only way the clearance lights could come on would be if someone has jumpered to that circuit or you are back feeding power thru the tan wire to the light switch resistor to the black and yellow wire. The black and yellow coming off the light switch should power the clearance lights, as well as park lights, tail lights and license plate. Check for 12 volts on the pink and red wire going to the light switch. That wire runs from fuse number 4 and its only purpose is to power the dash and clearance lights. Fuse 4 gets its power from the fusible link. Did you receive the wiring diagrams I sent you?

 

Sorry. I see where you said late '91. The wiring appears to be the same.

 

Fusibe links- check them out.

Daniel