4104 Engine Shut Down

[gus]

When I turn on the running lights the engine cuts off.

I also have no taillights. They are connected to the running lights.

Turn signals work fine, haven't checked the brake lights.

4104 running lights are not connected to the headlights.

I've been digging into the circuit diagrams but so far haven't come up with anything that makes sense?

[NJT 5573]

Gus how about a dead short in the running lites? Do they all lite up with the engine off? I don't know about your setup but you can probably unhook the wire that goes to the electric shutdown and hotwire around it to move your coach.

[gus]

NJT,

All the lights on a 4104 are independent of the engine switch (Called the Diesel Master Switch) including the turn signals. I like your dead short idea but can't understand why the running lights don't go out? All the lights work except the tail lights which are hooked directly to the running lights??

Today I discovered that the running lights also disable the reverse solenoid so I'm getting it narrowed down! I know I can wire around the shutdown switch but would prefer to find the problem. I have to get the TL working too but that shouldn't be too hard. Finding a short is another thing altogether but since there are no fireworks or melted wiring I'm thinking I don't have a short.

If there is a disconnect to the TL somewhere I will just wire around it if I can't find it.

I haven't checked the brake lights yet either, forgot about that, but the turn signals use the same bulbs as the brake lights?

I removed a few yards of excess wire today while trying to track down some of them. Most went to nowhere.

I'm finding a bunch of interesting connections along the way. Can't help but be educational!

I'm kind of suspecting a relay somewhere too because the problem is that the power to the shutdown switch is being cut off. When this switch has power it closes an air valve to keep air out of the engine shutoff air cylinder.

Anyone know what the bottom right corner relay is for? The manual doesn't give a clue. It shows a picture of it but doesn't mention it-strange? Guess I'll have to trace down the wires on that one too.

[WEC4104]

Gus:

My suggestion would be to check your brake lights and turn signals. My guess is they will work fine. If that is the case, get out a Phillips screwdriver and pull the left side dash panel. That, of course,  is where your engine shut down switch and reverse switch reside. (two of the noted problems).

My theory is as follows: Although the marker light switch resides on the right hand side panel, that switch also controls the dashboard illumination. It could be that one of the dashboard illumination bulb sockets has worked it's way loose and is touching the panel ground. I would check the illumination bulbs and the ground connection for that panel.

WEC4104

[gus]

WEC,

I think you have something on those dash bulbs. Today I noticed that the brake indicator light was also on about half normal brightness when the marker lights were on? At the same time the right front marker and tail lights were off but all other lights worked fine.

While I had the driver's side control panel open and was messing around all of a sudden everything worked just fine, the RF marker and TL were on and the engine didn't stop when I turned on the markers??

Shortly after that I noticed that the brake indicator was showing a tiny bit of light, about 1/4 as much as before but all other things were working normally. Shortly after that the light went out and never showed again unless I used the brakes.

When the marker lights were shutting the engine off so did the brake-that sure could have caused some anxious moments underway!!

With your comments I'm about ready to remove the right switch dash panel thinking the loose dash light is in there because of the brake indicator light being on without pushing the brake. If it isn't there I'll look at the left side. If I don't find anything I'll wire a switch directly to the engine shutoff so I can get power directly to it in an emergency. I already have the old interior lights switch as a spare with a wire to the rear.

One interesting thing when things were fouled up was that when I turned on the markers and the engine stopped the diesel master relay didn't trip. I could feel it trip when I used the master switch but not when I turned on the markers?? Very strange? If the relay didn't trip I sure can't figure out why the engine stopped.

[JackConrad]

I would also check all the ground connections. Poor grounds have a way of creating all kinds of strange symptoms.  Jack

[WEC4104]

Gus:

The more I hear about what you are seeing, the more I am inclined to believe your gremlins reside in the dash area.  The dim Brake tell tale and the fact that everything worked fine (briefly) when you had it apart keeps me thinking this is the area to keep persuing.

I have a few more pieces of information, and unfounded theories to throw your way...

First, I'll go back to a question you raised in your April 5th post. You were asking about an unidentified relay in the bottom right corner.  I am assuming you are asking about the one in the electrical compartment that is just forward of the transmission, and you are asking about the relay underneath the reading light magnetic switch.  If so, that would be the "temperature switch relay" and it is used on 4104s equipped with the mercury tube type temperature switch.  It is part of the Safety Control Relay System. But I don't think this item is involved in your particular problem.

Second, the Safety Control Relay System may be what is enabling your engine to shut off without the Master Breaker tripping.   I am way out of my league to discuss this circuit in detail, but I know that the 4104 has a circuit that shuts down the engine for high temp or low oil pressure related problems. But even if this circuit is causing a shutdown, I think that is a symptom, not the cause of the problem.   What I mean by that is, if you have a dash wiring problem, perhaps there is something screwy happening like there is electric bleed back through the oil pressure tell tale or engine hot tell tale, causing the safety control realay system to shutdown. That's just a wierd theory of mine, but it is the only explanation I can come up with to explain what you are seeing.

... and I agree 200% with Jack that grounding issues coud be the cause. I'd pull the dash covers and check all the connections to the dash illumination bulbs, tell tales, and ground connections.

WEC4104

[gus]

Thanks guys, good to get some more ideas.

It happened again today so I have the RH switch panel out to check for bad wiring/grounding. A bunch of these wires have cracking insulation and corroded terminals. Next will be the LH switch panel if this doesn't work.

Bad grounds are very likely the problem but the problem is-which one? I think I have cleaned a thousand corroded connections in the two panels and maybe even more ground connections all over the bus!

If I don't find this gremlin I'll go ahead and make a direct hookup to the engine shutoff solenoid with a separate switch and wire.l

I agree about the "Signal and Alarm  Wiring Diagram". That thing has me baffled. One problem is my diagrams are so small I can't read some of the circuit numbers/letters. My Manual has three of these little diagrams on one page!!

Anyone know a source for larger diagrams?

WEC4104,

Thanks for identifying that relay in the rear compartment. I have a suspicion that all the emergency lights and shutdown sensors have been bypassed because no warning lights/buzzers ever come on including low air. I intend to remedy that with a red warning light.

[4104bigred]

I do have the schematics for my 04 and can email them to who ever needs them. they are very easy to read
on the screen

chris

[gus]

Chris,

Thanks, I'm sending you a private email and do appreciate the offer. Don't understand why they aren't full-size in the Manual??

[gus]

Today I at least solved part of the gremlin problem. I found that the starter relay ground was hooked to the #2 Rear Electrical Compartment (REC) terminal which is supposed to be marker lights and TL? I can see how someone was confused because the first row of terminals has only four whereas all the others are five. The third terminal is supposed to be the starter relay so someone made an easy mistake. This eliminated the stop light TT showing with the marker lights on and the marker lights no longer shut off the engine!! Hooray!!

What I don't understand is how this has worked fine for almost two years?? It is probably because of something I unhooked during my cleaning out old wiring. Another reason to leave things alone!

However, the engine still shuts off when the brake pedal is pushed and I still have no TL?

I hooked up 12v directly to the trailer light connector and had TL so now I have to work back until I find the problem in this wiring. If I can't find it I'm going to hook up the TL to the old "General Light" switch and relay for the interior lights which are now hooked up direct since this switch still works. I'm not sure what this will do to the stop lights?

I suspect some of the numerous relays and rectifiers in the Alarm and Signal System, many of which are connected to who knows what. None of the alarm tell tales (TT) work including Low Air.

I'll probably never know what caused all this mess.

[gus]

I can see that there is little interest in these problems now but, take it from me, there will be a lot of interest if it happens to anyone else! Maybe someone will be able to use some of this info in the future, I sure hope it doesn't happen to anyone else though.

Today was interesting. I now have TL, brake and turn sig but the turn sig don't work with the brake lites on?

Best of all the engine now doesn't shut down when the brake or marker lights are on, hooray!

Also, I didn't mention this before, but the emerg engine shutdown now works. It didn't during all this fiasco even though it had worked for almost two years.

However, the turn signals flash both sides when the brake is used, kind of interesting and maybe not a bad idea.

After unwrapping all the rear light wiring harness I found that the TL were connected to either the emerg engine shutdown solenoid or the starter solenoid, I didn't take time to find out which but it is in the wire bundle to those two items? This is getting strange! I moved this connection to #2 terminal at the rear elect compartment as per original and the TL work just fine.

Two times during all this the starter switch wouldn't work. One time I narrowed that down to a missing ground which I had removed accidentally but never did figure out the second one.

Tomorrow I hope to resolve the rest of this mess and get on our way from AR to the west coast. Our original plan was to leave tomorrow but we won't make that.

After all the work installing the Honda gen and the new LP tanks I sure didn't need all this.

I can see why a PO would wire things kind of screwy just to get them to work for a trip since I have come to that conclusion a few times already!!

I have a very intimate relationship with this electrical system now!!

[Dallas]

Gus,
You may not think there is much interest in the wiring problem, but, you'll notice that the thread has been viewed (368 at this writing) many times.

On my 4103 I had many of the same problems you are having: miswiring, bad frounds, mouse food, squirrel condos, cracked insulation, etc.

I ended up replacing over 3500 feet of the original factory wiring to get it to the point there was reliable in a day to day sense of the word.
(whoda thunk that a 55 year old non electronic coach could have that much wire in it?)
It still isn't completely done, but it's 100% better than it was.

With your turn indicator/stop light problem, you might want to check to see what kind of signal stat turn signal switch you have. It may have been changed. There are a couple of different types, some that incorporate a separate brake light/turn idicator and some that use a single lamp on each side.

I swapped my original out with one I got off a wrecked semi and it uses a separate BL/TI setup.

Here are some of the different wiring set ups:

I hope this will help!

Dallas

[JackConrad]

Gus,
   Glad to see you are getting the problems corrected. I have not chimed in on this except to say "check the grounds" because I do not have any 4104 manuals and am not familiar with 4104 wiring. By the time we get these fine old girls (the coaches), who knows what has been doone to them. On our MC-8, I finnally said enough is enough, I completely rewired it. I had a pile of old cloth insulated wire and rusty circuit breakers & relays about 4' in diameter and about 2' tall that I removed. At least now I know all wiring is good and I drew schematics as I went. So, finally, I have accurate schematics should a problem occur.  Sounds like Dallas may have the answer to your last problem.  Jack

[gus]

Thanks Dallas and Jack.

I wish I had the luxury of changing all the wires but since I bought it converted that is just about out of the question. I really haven't had many wiring problems up to this time even though I had removed many, many old unconnectd/cut wires and mystery boxes.

Love those 4103s, tried to buy a couple but they had too many problems. It has just about the prettiest front of any bus ever made.

Grounds, grounds, grounds!!!!

Final Installment; the primary problem was that the TL and ground wires were reversed in the rear wiring harness. This harness had been added on because, I think, the TL are not original. I think the original lights had two tail and two stop/turn lights since there are four of them. Now all four are connected together and all do the same thing. They are what I call trailer lights, the kind that mount in floating rubber rings. Not sure about this though.

As I said before, I found some incorrect connections which I changed but I'm not really certain what caused the original engine shutdown and may never know. I'm not in the mood to trace out wires on the diagrams any more now that things are working properly.

My guess is that all the wiring faults caused the engine shutdown switch and TL to find improper ground paths which fouled up other things, sort of a domino effect.

My number one lesson from all this is each time I change any wiring or remove any electrical part I'll check for engine shutdown and light operation. There is nothing as frustrating as having the engine die when brakes are applied or marker lights are turned on, that gets your attention!!

Now we will start our 6000 mi trip to Seattle on Thur instead of tomorrow since a bunch of other things had to wait until the lights were working. I'm looking forward to a nice relaxing trip and taking in the many sights along the way.