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Old 05-03-2022, 06:46 PM   #1
Bus Nut
 
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Join Date: Dec 2020
Location: Las Vegas, NV
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Year: 1995
Coachwork: Bluebird
Chassis: International 3800
Engine: DT466 / MD3060
Help diagnosing Turn-Signal / Clearance Light issues

Hey Gang! It's been a while - we're rounding our 10,000th mile on our lovely 1995 DT466 International 3800. Smooth sailing so far, but as of a few days ago we've got a fun electrical issue to solve!

TLDR: Are the clearance lights and hazard / turn signals connected? Once flashers went out, my clearance lights now overheat. Replaced all flasher bulbs and get constant ambers but still no flashers.


The problem started with the flashers going out - all of the constant amber lights worked but when I hit either turn signal or the hazard lights, nothing flashes properly.
There is a slight off-time click, and the bulbs dim briefly, but not proper turn-signal behavior and the inside dash signal icons remain constant, they do not flash as usual.

Then, about 40miles down the road as I'm pulling out of the gas station to head to Walmart for new flasher bulbs, I smell electrical fire and see my dash control-pannel is smoking! I pull over immediately, shut everything down, and pull out the 10 screws - no fire, just smoke, we're good.
The clearance switch gets exteremly hot inside the dash, and is melting the wires somewhere.

What I've done so far:
  • I replaced all 8 flasher bulbs: 4 up front, 1 one either side, and 2 in the rear.
  • I also replaced the one clearance bulb that appeared burnt out. All clearnace bulbs now light up, and flash, but the switch still gets super hot after about 10 seconds.

All fuses look good inside.

My questsion for the gurus:
  1. Could these 2 issues be related?
  2. What would cause a short in the clearance lights wiring - old wires / if I replace all wiring inside the dash rat's nest, could this help solve and/or prevent this from happening with other circuits?

Happy to take some photos, or get into it if anyone has any ideas - I appreciate your time and willingness to help

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Old 05-03-2022, 11:21 PM   #2
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anything is possible ..

The switch getting hot....... that should never happen... I think there is a very good chance something is wrong inside the switch...... that is the clearance lights.....

I sure dont expect turnsignals.hazards to be interconnected to the clearance lights....but...I have seen a couple of buses with some sort of hack job "field fix" so anything is possible.

try this on for sized..... there is a power wire for the clearance lights that has some how worn through the insulation and is now making contact with a wire in the turnsignal/hazard system... so the when the clearance lights are "ON" they are also feeding power to the other system. Now, that interconnection is not a good connection has a lot of resistance....

that smoke under the dash would seem to be too much current going through wires and for some reason did not trip a breaker or blow a fuse.

that would indicate the power is coming in on a circuit that is a higher breaker capacity, like maybe blower fans, or maybe even main power cables connected to one of those big solenoids that is always on with the key on... some sort of big power is feeding little wires and resulting in letting the magic smoke out.

do you have any previous signs of rodents chewing on wires under the dash?

wires for clearance lights and turn signal/hazards -- where do those wires run along side each other?

this kind of electrical stuff is THE single most time consuming repair I do on machines... cars trucks boats airplanes chasing angry pixies takes time. I have seen multi layer circuit traces in fuse boxes go bad from a water leak in a front windshield that dripped into the fuse box, that corroded over the years and the fuzzy corrosion was conductive and caused multiple odd and strange problems. I have seen a ground strap connection on the passenger floor of a car with so much corrosion that the ground did not work correctly and that was under the carpet, under a shield under the center console. I have seen wires to fuel injection corroded to the point they broke and the injectors quit working...... that was inside a harness in an engine bay... I unwrapped 6ft of harness between the firewall and the engine to find that one. There was the coil wire that had spark jumping out the side and into a fuel shut off solenoid on a carburetor.... you would replace the solenoid and in a couple of hours of run time, the solenoid would be bad again.

any ways....you are not looking for a simple answer.... just the answer. Now that you have partially melted plastic under there this is going to be harder or easier... lay your hands and eyes on all the damaged wire and separate out so that none of them are touching... you can use paper as temporary insulation...you may find the smoking wire that is the cause when you do this.

vw air cooled beetles..... when the ground strap would fail on the engine/transmission to the chassis of the car. The clutch cable and the throttle cable became the ground pathways..... most of the time this is not super awful. but BUT when you turn the key to start the engine,,, you can watch the cables glow orange .... for a little while anyways....


william
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Old 05-04-2022, 09:11 AM   #3
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Quote:
Originally Posted by Bear Gerschafer View Post
Hey Gang! It's been a while - we're rounding our 10,000th mile on our lovely 1995 DT466 International 3800. Smooth sailing so far, but as of a few days ago we've got a fun electrical issue to solve!

TLDR: Are the clearance lights and hazard / turn signals connected? Once flashers went out, my clearance lights now overheat. Replaced all flasher bulbs and get constant ambers but still no flashers.


The problem started with the flashers going out - all of the constant amber lights worked but when I hit either turn signal or the hazard lights, nothing flashes properly.
There is a slight off-time click, and the bulbs dim briefly, but not proper turn-signal behavior and the inside dash signal icons remain constant, they do not flash as usual.

Then, about 40miles down the road as I'm pulling out of the gas station to head to Walmart for new flasher bulbs, I smell electrical fire and see my dash control-pannel is smoking! I pull over immediately, shut everything down, and pull out the 10 screws - no fire, just smoke, we're good.
The clearance switch gets exteremly hot inside the dash, and is melting the wires somewhere.

What I've done so far:
  • I replaced all 8 flasher bulbs: 4 up front, 1 one either side, and 2 in the rear.
  • I also replaced the one clearance bulb that appeared burnt out. All clearnace bulbs now light up, and flash, but the switch still gets super hot after about 10 seconds.

All fuses look good inside.

My questsion for the gurus:
  1. Could these 2 issues be related?
  2. What would cause a short in the clearance lights wiring - old wires / if I replace all wiring inside the dash rat's nest, could this help solve and/or prevent this from happening with other circuits?

Happy to take some photos, or get into it if anyone has any ideas - I appreciate your time and willingness to help
I had posted lots of wiring diagrams for an Amtran Re (1995) -> https://www.skoolie.net/forums/f49/a...ams-25055.html

I know your bus is different but it is still built on an International chassis so maybe these diagrams might provide some insight.

Post #2 has clearance lights and blinker circuits.
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Old 05-04-2022, 09:18 AM   #4
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You might also want to find your turn signal and hazard flashers, you could have two separate problems. I had an issue where my hazards didn't work and the turn signals acted weird, turned out both flashers were cracked and rusty (plastic housing filled up with water over time I guess). Took me forever to find the flashers tucked away in the electrical cabinet but once I replaced both problem solved!
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Old 05-04-2022, 10:00 AM   #5
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I had this very thing happen on my DEV bus and it burnt up the headlight switch (that bus doesnt have a CL light switch).. I found that one of the sockets with a dual bulb had gotten water in it so when my headlight switch was on it was driving both the high-watt filaments of the left turn signal and also the low watt of all the Clearance lights.. my headlight switch was suspect and so before it tripped the breaker it got the switch hot.. I found it was in a socket of the front fender mounted lamp that has a parking light and a turn signal both in it..
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Old 05-04-2022, 10:14 AM   #6
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Quote:
Originally Posted by Bear Gerschafer View Post
Once flashers went out, my clearance lights now overheat. Replaced all flasher bulbs and get constant ambers but still no flashers.

The problem started with the flashers going out - all of the constant amber lights worked but when I hit either turn signal or the hazard lights, nothing flashes properly.
There is a slight off-time click, and the bulbs dim briefly, but not proper turn-signal behavior and the inside dash signal icons remain constant, they do not flash as usual.

Then, about 40miles down the road as I'm pulling out of the gas station to head to Walmart for new flasher bulbs, I smell electrical fire and see my dash control-pannel is smoking! I pull over immediately, shut everything down, and pull out the 10 screws - no fire, just smoke, we're good.

The clearance switch gets exteremly hot inside the dash, and is melting the wires somewhere.
Is it correct to say that before this issue started everything worked properly and as expected with the exact same lights / flashers / switches as what you have now?

Is it also correct to say that everything that stopped working correctly (turn signals not flashing correctly, switch heating up, wire insulation burning) happened on or around the same day?

Quote:
All clearnace bulbs now light up, and flash, but the switch still gets super hot after about 10 seconds.
I'm confused. Are you saying that the clearance lights do - indeed - flash (along with the turn signals)?

Quote:
All fuses look good inside.
What are the values for the fuses protecting the clearance lights & turn signals? Either they're not correctly sized or something isn't wired correctly. A fuse should have blown before you wiring started burning.
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Old 05-04-2022, 10:51 AM   #7
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Engine: DT466 / MD3060
Thank you all - I'll try to address everything here:

Correct: everything worked fine up until the turn signals / hazards went out - everything failed within 24hours. Fun fact - we got our first mouse 2 or 3 days prior (he's gone now, RIP)

The only things different leading up to the failure:
  1. we just hit 10,000miles on our trip, nothing else is acting weird though.
  2. We just had our first mouse - cute but dead.
  3. Driving through dust storms in NM, UT, and NV.
  4. Using the hazards more on long climbs through the mountains in states mentioned above.

What works now: Running (amber) lights work fine. Clearance lights do light up, but the switch gets too hot - they also flash with the foot pedal, but I'm not using them until this is solved

Hazard / Turn Signals do not "blink": have an off-time tick, and all bulbs pulse a little brightness off-time, but they do not "blink" as usual, with the normal "tick-tock" sound. The arrow indicators on the dash remain constant instead of flashing.

My clearance lights are on a separate switch in the dash to the left, with a foot switch to make them flash.

Hazards and turn signals are on a lever-switch on the steeing column.

Headlights / running (amber) lights have another separate switch in a different location on the front dash, with a foot pedal for brights.

No fuses are blown, but our fuse box is verys suspicious - there are hardly any fuses in there compared to the daunting amount of wires in the dash switchboard. Everything has always worked so I just run with it.

Planned repair steps:
I plan to go through the switchboard wires ASAP, trace & replace all of the suspicious wires, then go through all of the light bulb sockets outside.


It doesnt sound like the clearance and hazards should be on the same circuit - but you have all confirmed my fears: This is going to be a pain in the a$$.

I can still use my turn signals manually, flipping the lever on/off on/off, so we can limp until I get somewhere I can post up for a while to go through all of the wires. We don't drive at night very often so the clearance lights shouldn't pose any problems either - as long as nothing else starts smoking!
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Old 05-04-2022, 10:57 AM   #8
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Did you find the wire(s) that were producing the smoke? That would give you a wire to chase looking for a short. You'd think a wire that was producing a lot of smoke would show evidence of heat damage to the insulation.
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Old 05-04-2022, 03:19 PM   #9
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Quote:
Originally Posted by Oldyeller View Post
Did you find the wire(s) that were producing the smoke? That would give you a wire to chase looking for a short. You'd think a wire that was producing a lot of smoke would show evidence of heat damage to the insulation.
It looks like it is from the wires leading to the CL switch - I haven't pulled everything out to chase them all to/from sources - it's cramped in there and we're in-between stops right now = major pain to pull everything appart right now.

When I turn on the CL, the back of the switch gets hot enough to burn my finger - I always drive with CL on, so when it started smoking the first time it was just from being left on too long without noticing the heat.

Just odd that everything went sideways at the same time - makes me thing our little mouse may have done some damage, or the original wires & bulb sockets all reached the end of their life at the same time.
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Old 05-04-2022, 04:39 PM   #10
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Quote:
Originally Posted by Bear Gerschafer View Post
It looks like it is from the wires leading to the CL switch - I haven't pulled everything out to chase them all to/from sources - it's cramped in there and we're in-between stops right now = major pain to pull everything appart right now.

When I turn on the CL, the back of the switch gets hot enough to burn my finger - I always drive with CL on, so when it started smoking the first time it was just from being left on too long without noticing the heat.

Just odd that everything went sideways at the same time - makes me thing our little mouse may have done some damage, or the original wires & bulb sockets all reached the end of their life at the same time.
With these old buses we run it could be mice, long standing abrasion or a crappy Mechanic's feeble attempt to upgrade the wiring. At least you have some wires to trace.
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Old 05-12-2022, 09:17 AM   #11
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My turn signal light on the side of the bus(behind the main door, is wired to come on with the clearance lights and also to blink. So maybe thatís where the two systems converge 🤷🏼

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Old 05-17-2022, 03:43 PM   #12
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Alright - so I've got the problem solved! Wanted to post the fix to close off the thread:

The clearnace light switch problem was the result of some old wires, or at least that is the only thing I could find. I got into the switch panel and replaced all of the wires and now everything seems to be working fine - no more smoke, no more hot switch!

The blinkers were just the result of the blinker fuse going out - I couldn't tell anything was wrong visually, unlike traditional fuses. But I could hear the fuse ticking off time, so I picked one up at Nappa for $27 and we're good to go!

Thanks for all of the replies, stay safe out there on the road!
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Old 05-18-2022, 09:59 AM   #13
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If you have a trailer plug installed. Pull it apart. It might have road debris built up and shorting it out.
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