Ripper

Got a truck in the shop the boss wants me to get hooked up to and we don't have any wiring schematics anybody got any ideas about these trucks. This ole truck was a cement truck at one time I am sure some cut something they wasn't supposed to but not to sure where to start looking.

hope the wires arent melted together

That is what is weird I have not yet found anthing melted together

Just an idea, have you tried replacing the relay with a known good one? I'm wondering if the relay could be stuck.

Yes, I bought 3 new ones for the old ones was missing when the truck was boughten. I then thought maybe just by luck I got some bad ones so I bought three more from Napa and the same thing was going on. I am at my wits end on this one. I thought maybe mice or something got in and chewed up the wiring so I got the dash wiring undone and checked to make shure the fur biting criters didnt do any damage.

Have you changed any headlights lately??? be sure you have the right headlight bulb installed, there are 2 diffrent numbers 9007 I beleive is the correct one for your truck!

But check with the dealer for the proper number!If you put the wrong light in one side it will cause this.

Thanks for the help I will look tommorow we bought this at the auction like this but I didnt think of looking at the light bulbs to see if they are the same I know both are burning only it is like there is a day time running light for they dont dim or brighten they just stay on all the time.

There have been problems with the headlight switches failing prematurely due to current spikes. I have also seen this sort of problem when the wrong headlamp switch has been installed. The switches for the different chassis that Mack manufactures often use switches that are similar in appearance but that have different pin locations.

I actually have the switch unplugged and the lights are still on, we got this at the auction this way. I am trying to get it going. You know though the switch dont have the factory plug in the back of the switch. Someone replaced it with female spade connctors. Do you know if the switch has to be in the circuit and working properly to complete the circuit so the lights will shut off?

I have tried everything but the headlights dont shut off. I have to remove the fuse or the relay to get them to go out. I have unplugged the headlight switch the multifunction switch the headlights wont go out. I was told by my local Mack dealer this truck would not have daytime driving lights. Help please..