Dash Electric Problem

My dash has a "Radio Power" switch with Aux and Main settings. This rig came with a very nice Alpine upgrade to the dash radio. However, it appears that the added boom box is wired to the chassis vs. the house batteries. I brought this up in a question last summer to get input on what was causing my chassis batteries to continually go down while parked. So even tho I switch to Aux (house batteries) while parked and using the radio, the chassis batteries still go down. For now I've learned to live with it and just keep the house batteries charged as needed.

Now, the problem. Yesterday while driving the rig, I noticed electrical burning smell -- then smoke from under the dash. After pulling over and cutting the engine I was able to look under the dash.  Fortunately, this model Winn Adventurer has the dash on hinges so I can raise it to see what is going on. I also noticed that I had forgotten to change the switch back to Main when I was ready to drive off. Under the dash, the harnesses  that appeared to lead to that switch cluster had become so hot they had melted the ducting from my heater.

I then tried driving again with the switch turned the right way. Everything was OK for awhile then smoke and smell again. This time, the heater duct was smoking. This duct is like a sewer hose in that it is housed in metal spring kinda wire. When things cooled down, I cut the entire length of melted ducting out of the system as the exposed duct wire was now against the metal of the chassis and looked like it was causing the lastest problem. The rest of my trip was then uneventful.

So my question is -- whey would having that switch turned the wrong way cause a potential hazardous situation like that unless something else is wrong? I "did" have the radio turned on when the problem occurred. (If I recall, I had picked up Al Hirt playing with the Boston Pops but I doubt that caused the problem.  ) Wouldn't current just come from the house vs. chassis batteries to the radio and while the chassis battery was doing it's thing with the chassis? It almost appears that current was coming from both at the same time to cause such overheating of the harness wires.

Bob Buchanan said:

.....I also noticed that I had forgotten to change the switch back to Main when I was ready to drive off......

Click to expand...

Hi Bob,

This is only a guess as to the cause of your problem, but certainly could cause the same symptoms.

Your dash Radio Power switch is like mine, in that it is suppose to supply power to the radio from the coach battery when the ignition is OFF. So the radio is powered by the coach battery when it is in the AUX position and is powered by the chassis battery when the switch is in the MAIN position AND the ignition is ON. It is a single pole double throw switch with the output of the switch (to the radio) being the center position and the input positions being either the chassis battery via the ignition circuit or the coach batteries.

Now if the former owner miss-wired the switch when he installed the new radio OR some other device so that the coach battery is connected to the chassis battery via the ignition circuit when the switch is in the AUX position, some of the charging current applied to the coach battery by the alternator while underway will flow though that wire. This "additional wire" would not have the capacity to handle the current demand and would over heat. If the switch is in the MAIN position it would not make any difference because the coach batteries are no longer in the circuit. In effect you would have the "normal" charge cable and the "new miss-wired" wire parallel to each other with both supplying current to the coach battery bank.

I have the same potential problem with my coach. When parked for extended periods, I connect a 10 AWG jumper wire from the positive of my coach battery bank to the positive of the chassis battery. This prevents my alarm system (powered by the chassis battery) and other parasitic drains from running my chassis battery down. If I left that jumper attached when I started the coach, a large amount of current would pass through it, as well as the normal alternator charging cable to the coach battery bank, depending on how low the coach battery bank is at the time. Any time I attach my jumper between the coach and chassis batteries, I put a red 3"x6" card on the dash console covering the speedometer. This reminds me to disconnect the jumper BEFORE starting the engine.

I am not sure how you can test this theory, especially since you have already fried some of the wires. You can pop that switch our of it's mounting hole by squeezing the tabs on each end of the switch housing (be sure to mark the switch so it can be installed correctly) and pushing it out. Now by tracing the wires from each of the outputs, you may be able to determine whether the previous owner "jumpered" the coach and chassis batteries.

I hope this gives you something to work with and check out.

Good Luck.

Richard

PS Theoretically, if the switch is wire as intended, you should be able to drive with the switch in the AUX position with no problems. I do it all the time. It just means that when you turn your ignition OFF the radio (and in my case the CB) keeps playing because the radio was never powered by the ignition; it was always powered by the coach batteries even with the ignition ON. If you drive with the switch in the MAIN position, only the ignition provides power to the radio.

PPS I hope this makes sense to you. After rereading the entire message it seems a little convoluted. If you have any questions, please ask them. Finally, your radio and boom box should both be wire to the coach batteries!

Bob,

Could it be just simply that the wire in the duct shorted between the back of the switch and ground? Vibrating down the road it wouldn't take much to get a tiny bit of duct wore off to cause a short.

Bob Buchanan said:

I also noticed that I had forgotten to change the switch back to Main when I was ready to drive off.

Click to expand...

Bob,

A followup question. How did you determine that you had to "change the switch back to Main when I was ready to drive?" As I mentioned in my ramblings above, that should not be necessary. Did you just assume that was necessary or did the previous owner tell you that?

Richard

RLSharp said:

Now if the former owner miss-wired the switch when he installed the new radio OR some other device so that the coach battery is connected to the chassis battery via the ignition circuit when the switch is in the AUX position, some of the charging current applied to the coach battery by the alternator while underway will flow though that wire. This "additional wire" would not have the capacity to handle the current demand and would over heat.

Click to expand...

Thanks, Richard. I appreciate the detail of your thoughts. This has been frustrating me for the past year since I bought this rig. I "have" been playing the radio w/it's boom box when parked because it is a outstanding sound system. But if I do, the chassis battery slowly goes down. I too have a positive lead from the house to my chassis battery to keep it charged while parked (with the reminder note on my steering wheel to unhook it before starting the engine).

My plan now is to just not use the Aux setting until I can get to an auto electric shop and have it checked out. I'm not an electrical guy other than basic stuff so don't feel comfortable messing with the ignition switch wiring. As far as I know, I have never driven the rig with the switch in the Aux position -- but can't say that for sure.

For now, turning the switch back to main while underway seems to have solved the problem. The second occurrence after that seems to have been solved by cutting the heater duct out of the area. So I surmise that the exposed duct wire was causing a short as it was exposed and touching the metal housing around the area. Actually, as Don suggests, that may have been the culprit all along. It may have just worn away exposing the metal duct wiring.

This whole thing may have been building for some time. I had never really looked at that duct before that meanders through the field of dash wiring. The harness wiring cover had melted into the duct and had to be pulled away before I could remove the ducting. Not sure of damage to the harness wiring leading to the dash switch. Will just have to have it checked out.

Will be leaving Arizona within the next few days and slowly winding up in NCal. Will be stopping in Laughlin so will probably take it to the dealer beside the Riverside park. They did some good work for me there last year. Hopefully, it won't flare up again before that. Not a thing one can check w/o driving far enough for the heat to build up again enough to start smoking and such.

Thanks again, Richard. Nice to get advice from someone with a rig much like my own. Good to see you in QZ again . . .

RLSharp said:

Bob,

A followup question. How did you determine that you had to "change the switch back to Main when I was ready to drive?" As I mentioned in my ramblings above, that should not be necessary. Did you just assume that was necessary or did the previous owner tell you that?

Richard

Click to expand...

The former owner never mentioned it. I have just always done that -- with this rig as well as the Tioga before this one. The thought that it "must" be done never entered my mind.  My thinking that it had something to do with the problem was based on (1) after I turned the switch off, it appeared to stop the problem, and (2) the wiring harness covering from that switch area was the one that melted into the heater duct.

Of course, as mentioned in my repines, the problem flared up again with the duct burning and melting in front of me until I cut that section out.

So the possibly shorted wiring in the duct may have caused the melting in that direction into the harness vs. the source of problem coming from the harness into the duct. ???

Alaskansnowbirds said:

Bob,

Could it be just simply that the wire in the duct shorted between the back of the switch and ground? Vibrating down the road it wouldn't take much to get a tiny bit of duct wore off to cause a short.

Click to expand...

Richard and Don:

Don, you may be right.

Decided to post a couple of pics to help explain -- and in so doing, discovered I have misrepresented the problem.

Seems that the harness wire that was melted into the duct was leading to the instrument panel vs. the Aux switch. So -- the melting probably "did" occur from the duct into the harness vs. the harness getting hot and melting the duct.

The "Wiring-1" pic has a yellow arrow pointing to the melting segment of the harness. I had to pull that away from the duct prior to cutting it out. That harness I see now goes to the instrument panel area.

Note that the section of duct that I cut out I placed in the foreground so you could see it's condition.

The harness below the instrument panel harness leads to the switch area -- and pic Wiring-2 includes the switch area on the face of the dash. That harness after more inspection is not damaged.

So -- me thinks now that the duct may have just worn through over time and exposed the metal core wiring to the metal housing to the left of the wiring area, eventually causing a short.  As you can see, the duct I removed is in pretty bad shape. Unfortunately, I do not know how much of that occurred during the recent event -- or how much it had deteriorated over time.

As my math professor used to declare, "A word to the wise is sufficient". If you purchase used rig, check out the heater ducts!!!

Looks as if there has been problems there before, much of your ducting works seem to be melted.  Not good for air flows from heater and AC.  Might should check and see if something is overloaded.  Much of that wiring looks congested.  But then that's just MHO  Cause mine sure doesn't look anything like that and I thought it was packed.

Bob,

I would be curious to know what wires are attached to the back of of your Radio Power switch. Originally, it should have had three wires attached to it.

                                  O---------O-------O
                                    |          |          |              Don't forget that the terminals for the
                                  Ign      Radio    Coach              switch are opposite to the labels
                                        Terminals at                      on the front of the switch.
                                      Back of Switch

If the previous owner wired the sound system to the ign terminal instead of the radio terminal, he would have essentially made a connection from the chassis battery to the coach battery when the ingition is ON and the switch is in the AUX position. This might not matter if the coach battery were fully charged when the engine was started but if the coach batteries were down when the engine was started, high current would flow through this "jumper" circuit.

A quick check of what is attached to the back of the switch might show what sort of connections he made. On the other hand, he might have attached the sound system, or the radio, to the wires after the switch and it would not be so obvious. He could have even picked up an ignition source other than that provided by the Radio Power switch but that would not change the overall "jumper" effect. If this "jumper" problem is the cause, the wires may have been over heating in the past but not burned to the point of causing a short to the reinforcing wire in the duct work.

When or if you have to have someone look at the problem, you may want to have a copy of my theory for them to look at before starting on he problem. It will at the very least give them something to consider in making a diagnosis, rather than just starting cold. I may be all wrong as to the source of your problem but my theory certainly could give the same symptoms and results.

From your pictures, it looks likes repairing this could be a major job, especially if any non-involved wires in the wiring harness are damaged. Those damaged wires could easily lead a technician down the wrong path. I know from experience that troubleshooting and tracing wiring problems can be a major PITA, especially if the wires are in a wiring harness.

Good luck.

Richard

PS The switch should not be hard to pop out. Just push on the retaining tab on one side of the switch and push that side of the switch out of the hole. Then do the same for the other side.

RLSharp said:

I would be curious to know what wires are attached to the back of of your Radio Power switch. Originally, it should have had three wires attached to it.

Click to expand...

Interesting, Richard. When I land in Laughlin I plan to have that checked out.  Also, there's the boom box thing. Have not had the time to follow the wires from the boom box to whatever power source supplies it. That appears to be the problem with the chassis battery running down. If the scenario you outline is true -- and I had just never turned on the radio with the switch in Aux mode, that could explain things.

Today I drove from Gila Bend to QZ.  I began by making sure the switch was on Main, with no radio on or heating/cooling. I also looked closely at the harness wires. I noticed that the harness to the switch covering was also melted away a bit. However, the wires inside both harnesses didn't seem damaged at all. So as mentioned in my last note leads me to believe the heat that caused the covering to melt into the heat duct came from the heat duct as a source vs. from the wires inside the harness.

Anyway, the 140 mile or so trip with the radio and dash air "on" was uneventful. I stopped every so often and checked the wiring and no over heating was happening. From the pic I posted, you can see another larger duct under the one that got fried. That one is from the air conditioner and it was cold and working fine. I did "not" switch to Aux during the trip. I plan to be sitting at the RV repair place in Laughlin when I do that.

Will keep you posted, Richard -- and thank you again. I will print your posts to take with me -- tho I think I understand the points you have made.

Bob,
Judging from the pictures, I'd say the ducting was the problem. It looks like the left side (in the picture) goes right under one of the fuse blocks. Possible short to one of the terminals there from wear over the years. Suggest replacing the entire section of ducting. The smell was probably the wire inside the duct burning the duct itself, and not any wiring. Again from the pictures, the damage to the wire loom doesn't look that bad. You should be able to carefully cut away the outer plastic shielding an inch or two on either side of the damaged area (side cutters would work well) to expose enough of the inside wires, then remove any damaged sections of wire individually and splice them together with crimp connectors. When done, insulate with electrical tape and/or another piece of wiring loom. Done this successfully many times.

Are you going to be in QZ any time soon? I'm leaving for there today, and would be happy to help you fix it.  

Karl said:

Are you going to be in QZ any time soon? I'm leaving for there today, and would be happy to help you fix it.  

Click to expand...

Well folks, since Karl posted this he did arrive in QZ -- and this AM we had a great breakfast at that little restaurant East of the Post Office. It was nice to get caught up on the latest. And as promised, he then diagnosed and fixed my dash problem. Thank you, Karl.

Seems the original heater duct actually came into contact with the back face of the circuit board supporting the instrument cluster. As the movement and "time" wore the covering off the duct wire it was metal on metal against one of the exposed circuits. (I had not looked there, whereas Karl was able to get into a contorted position with a mirror and flash light). The problem became obvious from the discoloration of that circuit. As we slowly closed the dash itself we could see how that duct would have been right against the circuit board. And, of course, if the duct itself was simply replaced as it originally was installed, the problem would eventually have happen all over again.

Karl suggested that I route the repaired heater duct "behind" the air duct vs. how it was originally on top of it.  We then came up with an even better solution by routing it so it will not go thru that area at all. The duct simply led to a an outlet on the left side of the steering column, whereas it is now on the right side of the steering column.

Richard, still do not know how the boom box is wired -- so that will have to wait until another day. However, for now, it does not seem to be the culprit involved in the electrical short around the heater ducting. Closer examination of the wiring around and from the Aux/Main switch indicates that there was not an overload of any kind. All the damage to existing wires, a dash light housing, and the harness covers appears to have been caused by the electrically charged heater duct wires.

Thanks again, Karl. I really appreciate your help today.

Bob,

I am glad to hear that Karl was able to diagnosis and fix your problem. Also glad that my theory proved incorrect. Had some sort of jumper connection between the chassis and coach batteries been the problem, more of your wiring could have been involved and probably more difficult to repair.

Richard

Aw shucks, twern't nuthin'. Besides, Bob did all the really important stuff - he paid for breakfast