Wipers only work when high beams are on. I suspect bad ground connections. Not my truck, a friends that called me. It is an older truck. I don't think there is a computer.

 

What year of truck? I would suspect a bad multi function switch if it is a 2004-08 year model truck. If not I can move it to the correct section of the forum for you.

 

I will find out. Where is the switch? How would I test it?

 

If it is an 04-08 it is the turn signal, wiper, brights/dim control lever on the steering column. I don't know of any way to test it, there is quite a bit to them since they control many things. I think most people just replace it. Here is what it looks like but this is for a specific truck so I can not say this will work with your friends truck since we dont know what his truck is exactly. https://www.tascaparts.com/oem-parts...bC12OC1nYXM%3D

 

Thank you. I will get the year and model but my calls have not been answered. I think they are on dial up internet so the phone does not work. I do not have a good E mail for him.