Western star low beams not working

I'm not sure everyone in this thread knows a Western Star--or what they're talking about for that matter. So let me help you out with some drawings for you:






(This drawing was borrowed from a 4900 that should be SIMILAR to your setup)

If you still can't figure out what the problem is, it might be worth it to you to take this truck into a certified WST dealer.

 

On many trucks the dimmer switch is part of the turn signal lever, it is a button on the end or the arm lifts like a car.

SignalStat is the most common manufaturer of OEM turn signal switches and has been since the old days when the dimmer switch was a button on the floor, as the times have changed SignalStat has started incorporating the dimmer switch in their devices as well as the canceling unit for the tractor stop lights.

Since the only two likely culprits for having no symptoms other than no low beams is the dimmer switch or the low beam relay the poster said "the SignalStat", I guess he assumed you would know that the SignalStat was where the dimmer switch is located.

It is very possible to have the dimmer switch fail before the integrated turn signal switch starts acting up so he was not saying you had a turn signal problem.

If your Western Star does not have the dimmer switch in the turn signal housing then it is quite old, in that case there would be no reason to look at the SignalStat, but if that is where your dimmer switch is then you need to check the low beam power out wire for current when you have the headlight switch on and the dimmer switch in the low beam position.