Headlight high beam help needed

[TheHubbardBus]

Asked this awhile ago in tech but got no answer.

Bus is an IC 3800, 2003 (navistar drivetrain, interior tag says Amtran)

High beams work, but only when the multi function switch on the steering console (turn signals) is held back towards me. They won't stay on, as soon as you release the switch lever and allow it to return to it's default position it goes back to low beams. There is no 'push forward ' as there might be in some vehicles. There's also no 'click' or feeling of a detent when you pull the lever back as I would expect to feel on, for example, our passenger car.

My main problem is due to lack of familiarity with the bus + no user manual, I don't know if the switch is working properly, with some relay downstream controlling the high beams staying on, or if the switch is responsible for holding the high beams on & is faulty.

Can anyone confirm how these are supposed to work?

[TheHubbardBus]

Let me ask this a different way...

If you have a bus like ours, how do you activate the high beams so they stay on? That's pretty much all i need to know.

Thanks in advance.

[BlackJohn]

To me that switch operates as it should as for hi beams.


Beam is on when held back and low beam when released again. I use that to flash the road ahead when needed.


Your headlight switch is where I would start and look for a dimmer switch elsewhere, usually on the floor, left side, upper toe area.


I drove my bus for two years to find how most things work and hope I remember these in future. Mine has a foot operated dimmer.


John

[TheHubbardBus]

Thanks for the reply John. That's what I was hoping, as it would indicate the steering column switch is functional.

So you're saying the steering column mounted switch (turn signal) only controls the momentary high beams, and there should be an old school floor switch to toggle between high/low staying on? That seems odd compared to any other vehicle I've driven

[BlackJohn]

Originally Posted by TheHubbardBus

Thanks for the reply John. That's what I was hoping, as it would indicate the steering column switch is functional.

So you're saying the steering column mounted switch (turn signal) only controls the momentary high beams, and there should be an old school floor switch to toggle between high/low staying on? That seems odd compared to any other vehicle I've driven

Hard to say as I have not had similar experience as you. I drive mainly older vehicles and the bus is a 97 GMC.


Yes a floor dimmer foot operated dimmer or might be the headlight switch has another position, or could be faulty inside. Have to ring it out if you have no floor switch.


John

[musigenesis]

Originally Posted by TheHubbardBus

Thanks for the reply John. That's what I was hoping, as it would indicate the steering column switch is functional.

So you're saying the steering column mounted switch (turn signal) only controls the momentary high beams, and there should be an old school floor switch to toggle between high/low staying on? That seems odd compared to any other vehicle I've driven

I think you pull back to flash the high beams and push it forward (where it will lock) to have it on all the time. Or it's the other way around. I'm heading over to my bus and I'll verify how it works - we have the same vintage.

[TheHubbardBus]

Originally Posted by BlackJohn

Yes a floor dimmer foot operated dimmer or might be the headlight switch has another position, or could be faulty inside. Have to ring it out if you have no floor switch.

John

Well, that brings me back to square one of not knowing if the steering column switch is faulty or operating as it should. What I'd give for a user manual.

Definitely no foot dimmer.

Thanks anyway.

[CHEESE_WAGON]

I second MusiGenisis. On most modern vehicles, you push forward (toward the dash) to use high beams, pull back to flash on a spring-loaded momentary.

Alternately, there may be a footswitch on the floor, though I don't think these have been used in years.

[TheHubbardBus]

Originally Posted by musigenesis

I think you pull back to flash the high beams and push it forward (where it will lock) to have it on all the time. Or it's the other way around. I'm heading over to my bus and I'll verify how it works - we have the same vintage.

Thanks musigenesis / cheese. That's how I figured it should work, but there doesn't appear to be a forward position. Either that or it's bound up / stuck / jammed.

[CHEESE_WAGON]

Originally Posted by TheHubbardBus

Thanks musigenesis / cheese. That's how I figured it should work, but there doesn't appear to be a forward position. Either that or it's bound up / stuck / jammed.

Then look on the floor for something like this...



I contacted a local Navistar dealer service department, and they said you might look on the console to your left where your switches are for clearance lights, etc. Dumb place to put the high beam switch, but the guy said he HAS seen them there.

UPDATE: A friend who drives a similar bus for school duty says that there is likely a switch on the console marked 'MASTER' that must be turned on before any other lights will work. Possibly part of a battery rundown protection? If this is the case with yours, likely it is turning on low-beams for daytime running lights, and the MASTER switch must be activated to supply power to the dimmer switch.

Something else I've seen on some vehicles is that the engine must be running in order for the headlights to be switched to high-beam.

[musigenesis]

Originally Posted by TheHubbardBus

Thanks musigenesis / cheese. That's how I figured it should work, but there doesn't appear to be a forward position. Either that or it's bound up / stuck / jammed.

Fudge, I just went over to my bus but forget to check out the high beams. Got into a trance planning my layout in the front. I'll check it tomorrow.

[TheHubbardBus]

I can't thank you guys enough! Haven't figured it out yet but at least i have a better idea how to approach the problem.

I am so out of my element with these buses. I've never worked on vehicles that could be configured in so many ways.

[musigenesis]

Originally Posted by TheHubbardBus

I can't thank you guys enough! Haven't figured it out yet but at least i have a better idea how to approach the problem.

I am so out of my element with these buses. I've never worked on vehicles that could be configured in so many ways.

I just checked out my bus. The lever pulls back and clicks and turns the high beams on, then pulling it back again (with another click) turns them off. There seems to be no way to just flash the high beams (the lever won't push forward). Sounds like maybe just the switch on your lever is broken.

[ol trunt]

Just a heads up. If your bus uses multiplex wiring all over the place as many 2000 + do, ringing out the wiring can be next to impossible. When I added driving lights to my little Isuzu powered (wired) bus I went through a handful of fuses until I discovered that the high beam wiring used the low beam ground wire as the positive for high beam. I hooked up the driving lights to the high beams expecting the driving lights to come on with the high beams and all that happened was it blue the headlamp fuse. I eventually bought a dealer level computer scanner that included a complete wiring diagram and traced my way to the error I had made.
Jack

[CHEESE_WAGON]

Originally Posted by musigenesis

I just checked out my bus. The lever pulls back and clicks and turns the high beams on, then pulling it back again (with another click) turns them off. There seems to be no way to just flash the high beams (the lever won't push forward). Sounds like maybe just the switch on your lever is broken.

*DING-DING-DING*

We have a winner! What do we have for him, Johnny?!

I would still verify whether there is a 'MASTER' switch like my friend has. Could be a feature for later models, and not applicable to the '03, but still something to check for and rule out.

[TheHubbardBus]

Sweet. Thanks for checking that out, musigenesis! Hope to get in there this weekend and see what's up. Just knowing how it's supposed to work is so much of a help.

Multiplex wiring... Never even heard the term. It does sound like one hell if a PITA though. Time to warm up my Google fu. Is this something that would apply to just the lighting circuits if present, or the entire bus?

We have a light switch to the left of the driver... Off / parking / on. I'm guessing this is the switch you're referring to, cheese? If so it makes no difference in regards to the high beams staying on. And I've had that switch on 'on' while testing. (Low beams are on anytime the bus is running regardless of this switches position... I assume that's the daytime running lights)

[ol trunt]

Here is a short discussion of multiplex wiring by Thomas built bus:

https://thomasbuiltbuses.com/content...-fall-2012.pdf.

The system monkeys with just about every electrical apparatus in the bus.
Jack

[TheHubbardBus]

Thanks, Trunt. Examining my wiring it looks like they're individually numbered. Would you know if that's a sure-fire indicator this type of wiring scheme is being used? Is there any other system component that would be a definitive indicator? I've got so much to learn now I was really hoping at least one thing - like a simple negative-ground wiring system - would be familiar (lol).

[wlgroff]

My 96 Navistar 3800 did the exact same thing. It is all in the turn signal / hi-lo switch on the steering column. As I remember that switch can be removed by taking out two screws and disconnecting the wiring harness. Once you are inside, there is a plastic box that has a seam coming apart. I was able to reassemble it with super glue and it has held up just fine. Or you can buy a new one from navistar for somewhere around $90.

[1dmpo]

Originally Posted by TheHubbardBus

Sweet. Thanks for checking that out, musigenesis! Hope to get in there this weekend and see what's up. Just knowing how it's supposed to work is so much of a help.

Multiplex wiring... Never even heard the term. It does sound like one hell if a PITA though. Time to warm up my Google fu. Is this something that would apply to just the lighting circuits if present, or the entire bus?

We have a light switch to the left of the driver... Off / parking / on. I'm guessing this is the switch you're referring to, cheese? If so it makes no difference in regards to the high beams staying on. And I've had that switch on 'on' while testing. (Low beams are on anytime the bus is running regardless of this switches position... I assume that's the daytime running lights)

Your daytime running lights may be your problem. I had my bus for a year and couldn't figure out why I couldn't get the highbeams to come on at all. Then I spent the time one day trying to figure out how to eliminate the daytime running lights because we had slept in a rest area on night in the cold with the engine running and the stupid headlights were on all the time. I found a fairly large heatsink looking deal with a ten wire pigtail plugged into it. unplugged it, suddenly everything worked!!! No more DRL and my highbeams started working like they were supposed to. Might be worth checking into. I have sense seen the DRL control also look like just an extra large square black relay box. but all that have have seen will be clearly marked with DRL control or Daytime Running Light Control. Good luck.