I have a 90 B250 and the PS low beam is not working, it's the only light that's out. The first thing I did was replace the bulb but thinking that was the problem but unfortunately it wasn't that easy. So..... my question(s) are, is each side headlight on their own circuit? Is it possible that the headlight switch or dimmer switch is the problem. I am not really sure where to start my search other than to start checking the wiring with a voltmeter. Anyone have any suggestions on possible causes? Thanx in advance for any help...

 

 

Are the different sides and the high/low all on different circuits?

 

You can get your wiring diagram here:
http://www.bbbind.com/free-tsb/

Do not register, you can go directly in from what I remember. The files you download need to be opened in Adobe should your browser get confused.

 

If it's only one headlight it should be easy to troubleshoot. Take the headlight out and use a voltmeter to see if you're getting 12 volts DC at the low-beam connector pin while the headlight is on. Be sure to ground the other meter lead first. If you have voltage the only other thing it could be is a bad ground to the headlight but that's not likely because you mentioned you have hi beam working. So, most likely it's a bad headlight (even if new) or no power at the connector.