International 4900 headlight Dimmer switch

[PeterG]

Had some problems with my headlights not working. Thought it was bad ground, as sometimes they would go on, sometimes not. When they worked, the bright lights worked as well. I had a mobile mechanic come out and get the headlights to work again. However, now when you step on the headlight dimmer switch to activate the bright lights, the headlights go out! Mobile mechanic says I need a new Headlight floor dimmer switch? Does this sound right to you guys? Also, for a 1990 4900, they want $100.00 plus dollars for the LH211225 switch. Can I just get the $12.00 one a the auto store and hook up the three wires?

 

[Jonas302]

Yes you can use a parts store one and yes its a likely problem with the headlights
Grab a test light with the lights on you will have power coming in and should have bright or dim leaving on the other terminals test it before replacing

 

[Theweldor]

Sure sounds like the dimmer switch. The parts store one will also work.

 

[PeterG]

Ok, thanks for the replies. Two questions. The real international part has three colors of wire which are red, blue, and black.
The NAPA switch has two opposing flat blade terminals and one sideways. There is no indication of what is what. Any concern with voltage and amps. International part on one web site says 14 volt and 20amps. Not sure what the NAPA one is.

 

[kshansen]

Sure sounds like a bad dimmer switch!

One option would be to go to this site:
https://www.napaecatalog.com/app.php?RelId=6.5.6.3.14&Archival=1&BookCode=crb18flx

Then over to the upper left click on the "Search tab" and type in "Dimmer Switch" that should take you to at least a page of the dimmer switches NAPA has you should be able to find one that looks very close to yours even if in the description it does not list your truck.

I know the same dimmer floor switch we used on the 1970's Ford pickups worked on the 1980's Mack trucks we had at the quarry.

 

[kshansen]

Ok, thanks for the replies. Two questions. The real international part has three colors of wire which are red, blue, and black.
The NAPA switch has two opposing flat blade terminals and one sideways. There is no indication of what is what. Any concern with voltage and amps. International part on one web site says 14 volt and 20amps. Not sure what the NAPA one is.

Well it's not exactly rocket science to figure out what is what on the switch!

If you have an electrical tester that will check continuity hook it up between and two terminals with out pushing the button on the dimmer switch. Make a simple sketch of the terminals on the switch.

When you find the two that have continuity make a note of which two.

Then push the button on the dimmer switch once and now check for continuity again. When you find the two that again show continuity you will notice that one of those is also one of the ones that showed continuity in the first check. So in the sketch mark that one as "HOT".

Now find which one of the three wires in the truck harness shows 12-14 volts with headlight switch in the on position. That is the wire that gets hooked to the terminal you marked hot in your sketch.

Now comes the simple part hook one of each of the other two wires to the other two terminals on the switch. It makes no difference which one goes where as long as you have the hot wire hooked to in input terminal of the switch.

It should take you way less time to figure out the "hot" wire terminal and get the lights working than it has taken me to type up all this description!