Low beams not working

[Boppie]

So I have a issue with my 1983 109, on the way home I lost my low beams. High beams work and all the signals do what they should, but the low beam are not working. Can this be a switch issue? What steps should I look at in trouble shooting this. Thanks in advance.

[stomper]

Unhook the floor dimmer switch and then touch the green wire to each of the other two. If they both activate the lights (with the headlights switched on, the switch is the issue.

Very common in wet and snowy environments. Especially when salt is added to the equation.

[o2batsea]

I moved the switch up to the dash.

[Boppie]

I don't have a floor switch, I have the three position switch on the dash.
When in the up position its off, middle parking lights, down headlights. The high beams turn on, so would this be within the high and low beam switch in the steering column? I would be about to drive the truck if it wasn't the high beams.

[SafeAirOne]

Remove the grille on the front of the truck.

In the mess of wires under there, find where the big blue wire with a red tracer goes into the black rubber 4-way connector, along with the 2 smaller blue with red tracer wires.

Remove the wires and clean the bullet connectors and the 4 way connector's contact surfaces. Reassemble, (presuming the brittle metal on the inside of the 4 way connector has survived) then test low beams. If they still don't work, leave the lights on and mess around with the wires and connectors till good contact is made.

I'm very confident this is your issue, however, if it still doesn't work, check for 12 volts between the big blue/red tracer wire and a good ground and we'll go from there.

I'm sure somebody will be along shortly to say that the ground connections are faulty, but they're not.

[SafeAirOne]

And, just in case you read that last post before I corrected it, you should be working the blue with RED tracer wires (dipped beam), not the blue with WHITE tracer wires (main beam) that I originally posted.

[Boppie]

Thanks, I will give that a go, I am sure the wires haven't been cleaned in a while and they need some cleaning. I added this picture of the dash, the leaver for the high and low beams looks clean. All the fuses look good.

[SafeAirOne]

Your problem isn't with the fuses and isn't terribly likely to be with the main/dipped switch on the stalk.

The schematic of the entire SIII electrical system is available on the RN online catalog. Just go under the "Series I, II III" menu and click on electrical. It'll be one of the two PDFs on the bottom of that page.

Or just click this I suppose: http://5037e1fccabb179f1658-62e5af32.../LR-page84.pdf

[SafeAirOne]

And just to help you make sense of the schematic, the headlamps (main AND dipped) get their power directly from the battery, via the light switch on the dash. Once this switch is closed, power for the headlamps (main AND dipped) goes through the main/dipped selector switch on the stalk, where the power is either sent down the blue/red wire to the dipped beams via the 4-way connector under the grille where it is split and sent to each headlamp OR down the blue/white wire to the main beams via their 4 way connector under the grille where it is split and sent to each headlamp.

After the power gets done making light in each of the headlamps, it is sent back to the battery through a ground wire attached to the radiator support panel above the grille. The same ground wire is used for the main AND dipped beams on each headlamp--That's how you know that the grounds are good--the main beam works just fine and it uses the same ground as the dipped beam.

So, if the main beams work fine, then the most likely place where the fault lies is in the connection where the power is split off to each of the headlamps.


There IS one caveat, however: If there was a short in the dipped beam circuit, say if the blue/red wire chafed through and grounded out against some metal while the headlights were on, then, being an un-fused circuit, the wire could have overheated and messed up the dipped beam contact on the switch on the stalk (melted the plastic around the contact).

This happened to me once and I had to disconnect the main beam circuit and use it to power the dipped beam circuit till I received a replacement stalk.

The odds are very low that this is your problem though.

[ignotus]

A test lamp can really help in finding where the lectricity is going....or not going. Highly recommeded bit of kit. OH!, and print out the schematic to take to the car and for future use....