'87 Windcruiser, 12V appliance power issue

87Itasca · January 16, 2016, 09:48 AM

Hi all,

The biggest issue with my Windcruiser right now is a lack of power to 12V appliances when the engine is off.

When hooked up to shore power, all my interior lights work, as does the microwave, AC units, etc.

My control panel, water heater, water pump, power step, and refrigerator control panel (therefore the whole fridge) do not. If I have the engine running, and the battery switch set to the Dual position, everything works correctly. If the switch is set to the middle position (which the owners manual says I should do when parked) none of the appliances listed above work. If I leave it on Dual with the engine off, they still do not work. Only when the engine is running (or the key turned to ON), do they work.

When it is not hooked to shore power, nothing works at all unless the engine is running, and the battery is set to dual mode. Then the lights, and all the 12V stuff works, as I believe is correct. Once I shut the engine off, the whole coach goes dead, and I have no lights or anything inside unless I restart the engine. I cannot test with the generator at this time, as it is currently partially disassembled.

It likely is related, but I cannot "see" the condition of my aux. batteries as well. There is a switch to check the voltage of them, and I can check the main battery, but when switched to AUX, the gauge does not move to indicate the condition of the batteries. When checked manually with a meter, they are about 12.5 V.

I can't imagine having to keep the engine running to run the fridge control board, water pump, and other stuff mentioned above. Any idea what is wrong, or is this correct operation?

Rickf1985 · January 16, 2016, 10:42 AM

Your coach battery switch is turned off. There should be a switch somewhere, mine on my 89 Winnebago is on the dash by the radio. On my Pace Arrow it is in a cabinet above the entrance door. It should be marked Coach power or coach battery shut off. Something like that. That switch is in addition to the switch you are mentioning, all you are doing with that switch is providing power from the chassis battery. If you find the switch in question and it will not engage then switch the other one and then try the coach switch again and it should engage. at this point you will be able to charge the batteries and you can also switch the chassis battery back off like you have been doing. Make sure the coach batteries are full of distilled water but if they are completely dead they are going to need to be replaced.

87Itasca · January 16, 2016, 11:42 AM

I have one that says "AUX Batteries" that is selected to ON, and there is a green light, but that light does not come on unless I am in Dual mode, with the engine either running, or the Key switched to ON.

According to the owners manual, the light will come on when connected to shore power, and if the converter is equipped with a battery charging section. Mine does not come on in the instance, however, I do hear the battery charger kicking in from time to time to charge the batteries. All the 12V fuses in the converter are good, as are the circuit breakers.

There is a small On-Off switch by the entrance door, above the switches for the floor, ceiling, and door lights, but I have yet to figure out what it does. I think it's for the electrical switches on the exterior of the RV, which are right in the same area, but I haven't tested them to see.

Also, all batteries are about a year old, and have all been tested and are in good order. I could see dead coach batteries causing 12V stuff to not work, but that's not the case in this instance.

Rickf1985 · January 16, 2016, 12:11 PM

It sounds to me like the latching relay that controls that function is not working. Dave has some really nice diagrams on just this subject. You could try the search function on the top right of the page. I am absolutely terrible at searches so I am no help in suggesting what to search for. I am hoping Dave sees this and jumps in with is famous diagrams. Do you know where the relays are? If so there are two Fuses on the relay, one on each side of the relay itself and one of them may be bad. They are 5 amp plug in automotive style fuses. Do a search for "Latching relay" and you will see what it looks like and then you know what you are looking for on your rig. A latching relay stays in the position it was last changed to without requiring power to hold it there. The one for the coach battery disconnect works off of the coach battery power though so if they are dead it may not change over. It "Should" change when you connect the chassis battery though, that is why I suspect the fuse on the relay.

Rickf1985 · January 16, 2016, 12:19 PM

Here is one thread I found with picturs of the relays. You are looking for the second one in the picture. Not the silver one. The silver one is the one you have been unsing to switch the chassis battery. The one with the light will be the other one and will have one or two fuses on it.

http://www.classicwinnebagos.com/forum/index.php/topic,7600.msg64497.html#msg64497

And here is one that shows the relay with a diagram showing the fuses.

http://www.classicwinnebagos.com/forum/index.php/topic,5977.msg23115.html#msg23115

TerryH · January 16, 2016, 05:58 PM

Quote from: 87Itasca on January 16, 2016, 11:42 AM
however, I do hear the battery charger kicking in from time to time to charge the batteries.

What you are hearing may be the cooling fan for the converter.

DaveVA78Chieftain · January 16, 2016, 11:17 PM

Sounds like the relay in the converter is working correctly, Selects converter power when on shore power. De-energizes and provides battery power when not on shore power.

I think the AUX Battery relay is not working correctly

The contacts in those relays have a bad habit of getting pitted and loosing connection. I think it would be located by the coach/chassis isolator typically located in the battery well (under steps?). In your case, the isolator relay would be connected on the output side of your AUX Battery relay (to coach system on that diagram) because you get voltage when the engine is running and in DUAL. You can test if the AUX relay is the problem by shorting across the 2 large terminals to see if you then have power to the rig.

Rickf1985 · January 17, 2016, 10:05 PM

I'll bet it is out under the hood just like mine. W%

87Itasca · January 18, 2016, 11:40 AM

Yes, they are under the hood. I'll try and take a peek at them when I get a chance this week and check the fuses. I know they have been replaced before, as they are neon colored. One is red, and one is green, I believe.

Once I can get that issue resolved, it'll be "livable" inside.

87Itasca · January 18, 2016, 11:57 AM

These are the culprits, I assume?

Looks like someone has been in here before...

NOTE: Fuse is not missing, I had it in my hand when I snapped the photo. One is a 10A, the other is a 30A...

DaveVA78Chieftain · January 18, 2016, 04:33 PM

1st photo = Aux battery cuttoff relay
2nd photo = chassis/house battery cross connect relay

Aux battery relay is not like a normal relay. It is a mechanical latching relay so the relay coil does not have to have constant source of power to it. A pulse from the switch in one direction causes it to latch. A 2nd pulse of reversed power causes it to unlatch. The switch simply reverses the B+ and ground leads. The switch returns to a center "OFF" position when you release it.

Rickf1985 · January 18, 2016, 08:54 PM

You know the bottom one is working so on the top one be sure to check those fuses on the sides of the relay.

On edit, I see where you checked the fuses, did you check them with a meter? I have seen many that looked good but were not. ALL of the connections on that relay are suspect! They all need to come apart and be cleaned.