Headlights stay on all the time. 1998 International/Thomas 3800

[JBird152]

My headlights stay on all the time now. A while back, the headlights would flicker or turn on at random (while parked-ignition switch off).
I now have to disconnect the battery cable to kill the lights. I'm assuming a relay has gone bad somewhere, but I don't know which relay to check.
Does anyone have a wiring diagram and/or recommendations on where to start looking?

[Brad_SwiftFur]

I can't remember if there is a relay, or the power just goes through the switch. Also, does your bus have automatic daytime headlights? That module could be responsible too. Mine has/had the ADRL (I pulled the fuse for it).

[JBird152]

Yes, it has either the ADRL or just a constant on when you turn the ignition switch to run (not sure if there is a difference).

Where would I find the module and the fuse? Do you have a pic of the fuse panel schematic?

I pulled the connectors off the back of the ignition switch and the lights stayed on. I pulled the connectors off of the headlight switch and the lights stayed on.

The headlight switch is the push-pull type with dimmer.

[Mountain Gnome]

I really think it is a relay somewhere, but I can't tell you where...

[BlackJohn]

A faulty dimmer will cause this condition. pretty sure no relay is involved in headlight circuitry.


Not an easy fix if dimmer is on the steering wheel.



Good luck.


John

[Mountain Gnome]

The daytime running lights in my bus use a relay, methinks.... But mine's a BlueBird.

[Brad_SwiftFur]

Originally Posted by JBird152

Yes, it has either the ADRL or just a constant on when you turn the ignition switch to run (not sure if there is a difference).

Where would I find the module and the fuse? Do you have a pic of the fuse panel schematic?

I pulled the connectors off the back of the ignition switch and the lights stayed on. I pulled the connectors off of the headlight switch and the lights stayed on.

The headlight switch is the push-pull type with dimmer.

My IH/BlueBird has a similar headlight switch. The ignition switch isn't (as far as I am aware) tied to the headlights, but the fact that you disconnected the headlight switch and still had lights helps me a lot.


I'm not sure where the ADRL module is but I remember there was a fuse for mine (which I pulled). I'd like to remove my ADRL module, since pulling the fuse seems to have caused my parking brake indicator to stop working (the bulb has been checked and replaced). I'm not sure where it is, though, or what it looks like. Anyone?

Originally Posted by BlackJohn

A faulty dimmer will cause this condition. pretty sure no relay is involved in headlight circuitry.


Not an easy fix if dimmer is on the steering wheel.

The dimmer has to be getting voltage from somewhere. If the headlight switch is off, then I'm not sure where it would be getting voltage from.

Originally Posted by Mountain Gnome

The daytime running lights in my bus use a relay, methinks.... But mine's a BlueBird.

Uses a relay, likely, but where's the ADRL module? I'd like to remove mine and restore function to the parking brake light.

[BlackJohn]

Originally Posted by BlackJohn

A faulty dimmer will cause this condition. pretty sure no relay is involved in headlight circuitry.


Not an easy fix if dimmer is on the steering wheel.



Good luck.


John

So there is no misunderstanding, my wording wasn't the best, sorry.


I had said dimmer switch when in reality it should be the hi-lo beam selector switch. Can be on the floor or steering column that is why I mentioned it is a tough job on the column.


Gnomer, hear ya on the DLR's but think the circuits aren't connected at all off the top of my head, no diagram to prove it unless someone else can post one.


Happy 420


John

[EastCoastCB]

A thomas I'm looking after did that. The DRL module was bad. Disconnected it.

[JBird152]

Originally Posted by BlackJohn

So there is no misunderstanding, my wording wasn't the best, sorry.


I had said dimmer switch when in reality it should be the hi-lo beam selector switch. Can be on the floor or steering column that is why I mentioned it is a tough job on the column.


Gnomer, hear ya on the DLR's but think the circuits aren't connected at all off the top of my head, no diagram to prove it unless someone else can post one.


Happy 420


John

John,

Thanks for the clarification. The hi-lo selector is on the column. The selector switch still turns the high beams on and off.
Are you saying that the switch may have failed on the low side and could be causing the issue?

[JBird152]

Originally Posted by EastCoastCB

A thomas I'm looking after did that. The DRL module was bad. Disconnected it.

Where is the DRL module located?

[BlackJohn]

Originally Posted by JBird152

John,

Thanks for the clarification. The hi-lo selector is on the column. The selector switch still turns the high beams on and off.
Are you saying that the switch may have failed on the low side and could be causing the issue?

Exactly JBird. Two sections to the switch, one does the beam selection.


To prove it disconnect battery. Test each side thru the connector for continuity from the selector switch when you move it.
Hope this helps, I just forgot what your problem is,


John

[EastCoastCB]

Originally Posted by JBird152

Where is the DRL module located?

I can't recall. Its in the electrical panel. I found it using google.

[JBird152]

Originally Posted by BlackJohn

Exactly JBird. Two sections to the switch, one does the beam selection.


To prove it disconnect battery. Test each side thru the connector for continuity from the selector switch when you move it.
Hope this helps, I just forgot what your problem is,


John

I pulled both of the connectors off of the hi-lo/turn indicator switches on the column and the headlights are still on.

[Brad_SwiftFur]

At this point I'm reasonably sure you've got a problem with the ADRL module/relay(s). There's a fuse for it (and I don't remember which one it was) that you can remove to disable it. I want to say it was an unmarked fuse to the left in the fusebox.

[JBird152]

Originally Posted by Brad_SwiftFur

At this point I'm reasonably sure you've got a problem with the ADRL module/relay(s). There's a fuse for it (and I don't remember which one it was) that you can remove to disable it. I want to say it was an unmarked fuse to the left in the fusebox.

Many thanks. We know what it isn't... We shall keep digging.

[JBird152]

Success!
I was able to locate the DRL module and remove it. Headlights function how they are supposed to now.
Many thanks to everyone for the brainstorming and troubleshooting!

[Brad_SwiftFur]

Originally Posted by JBird152

Success!
I was able to locate the DRL module and remove it. Headlights function how they are supposed to now.
Many thanks to everyone for the brainstorming and troubleshooting!

Excellent. Where was it and what did it look like?

[JBird152]

It was in the lower panel by the left foot, when seated in the driver's seat. I was able to follow the bundle down from the steering column and locate it that way.

Here is the module and it looks like corrosion was the culprit. I'm glad that bug is out of the system now. Back to the build...

[JBird152]

Originally Posted by BlackJohn

Exactly JBird. Two sections to the switch, one does the beam selection.


To prove it disconnect battery. Test each side thru the connector for continuity from the selector switch when you move it.
Hope this helps, I just forgot what your problem is,


John

That switch was by far the cleanest part that I have seen on this bus! The guys at the bus barn must have replaced it not too long ago.

Thanks for pointing me in the right direction