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JLMunsil · 12-08-2017, 07:41 PM

The solenoid is used to combine the battery banks. When the banks are combined the one with the higher voltage will feed the other until the voltages are equal.

The signal for the solenoid to close comes from the vansco when one of the banks reaches 13 volts for 15 seconds. Does not matter what the difference to the other bank is. Does not matter what causes the voltage to increase. The alternator, the inverter charger, or an external charger all can do it. Chassis battery voltage 13 volts, Coach battery voltage 13 volts, or the boost switch are the inputs to cause the solenoid to close.

The two small wires attached to the solenoid are the signal wires one positive one negative. Does not matter which stud they are on just one per stud.

The number 19 light is the indicator that the vansco has recognized that one of the banks has reached 13 volts.

If the house batteries are above 13 volts and the #19 light is not coming on, than the vansco is not recognizing the house battery voltage. I am not sure where that signal comes from. Need to look at the vansco pinouts to see where it might come from.

This all works thru the rear vansco. The front vansco is only involved to supply the signal to the rear vansco when the boost switch is pushed.

When the ignition is on it uses the chassis batteries. When the ignition is off the vansco uses the coach batteries,

RVPioneer · 12-08-2017, 08:09 PM

Quote:

Originally Posted by JLMunsil

The solenoid is used to combine the battery banks. When the banks are combined the one with the higher voltage will feed the other until the voltages are equal.

The signal for the solenoid to close comes from the vansco when one of the banks reaches 13 volts for 15 seconds. Does not matter what the difference to the other bank is. Does not matter what causes the voltage to increase. The alternator, the inverter charger, or an external charger all can do it. Chassis battery voltage 13 volts, Coach battery voltage 13 volts, or the boost switch are the inputs to cause the solenoid to close.

The two small wires attached to the solenoid are the signal wires one positive one negative. Does not matter which stud they are on just one per stud.

The number 19 light is the indicator that the vansco has recognized that one of the banks has reached 13 volts.

If the house batteries are above 13 volts and the #19 light is not coming on, than the vansco is not recognizing the house battery voltage. I am not sure where that signal comes from. Need to look at the vansco pinouts to see where it might come from.

This all works thru the rear vansco. The front vansco is only involved to supply the signal to the rear vansco when the boost switch is pushed.

When the ignition is on it uses the chassis batteries. When the ignition is off the vansco uses the coach batteries,

Looks like you've identified the probable cause of why the OP's chassis batteries aren't charging on shore power. VMM is not recognizing house battery voltage and switching solenoid to charge chassis batteries. Now we need to find out why. Bad connection, bad VMM, bad gremlins? Great info.

On my 2005 it sure seems like the VMM uses the chassis batteries with the ignition off. It has drained the batteries when stored without power in the past and it goes off when I throw the chassis disconnect switch.

JLMunsil · 12-08-2017, 08:24 PM

The VMM is powered by the chassis batteries.

When the ignition is on it looks at the chassis batteries voltage to determine when to energize the solenoid to also charge the coach batteries.

When the ignition is off it looks at the coach batteries voltage to determine when to energize the solenoid to also charge the chassis batteries.

JLMunsil · 12-08-2017, 09:06 PM

I think the # 18 pin on the J1 connector is the house battery sense wire and the # 19 pin on the J1 connector is the chassis battery sense wire.

The J1 connector is the 35 pin connector on the same side as the 23 pin connector. It is opposite the round 3 pin connector.

Pull the connector and check for voltage. Turn off the chassis battery disconnect first.

JLMunsil · 12-08-2017, 09:48 PM

With the VMM face up and looking at the side with the 35 pin connector the top left is #1 pin and the bottom right is # 35 pin. The corresponding # 18 pin on the wires coming to the VMM is the one to check .

Janet and Todd · 12-08-2017, 10:11 PM

The black and white wires in the shrink tubing go to the stud on the right. The single black wire goes on the left. I do believe it makes a difference.

swprdog · 12-09-2017, 09:03 AM

JLMunsil: Great info: I think i'm narrowing it down. It makes sense that the VMM is not sensing house battery voltage because I have swapped forward and aft VMMs several times and the results have been the same. I did check pin voltage earlier but I think it was the incorrect pins. Once it warms up a little I'll go check it out. (I keep the coach in a heated shop but the walk from the house to the shop is COLD). Thanks again

swprdog · 12-10-2017, 11:10 AM

I tested the pin and voltage was good. I've been thinking it may be intermittent signal to the VMM thus not seeing it for 15 seconds. I will try to repin the connector. Has anyone done this who can give me guidance on pin style? I've also been thinking of wiring a jumper, with a switch, from the hot side of the house batteries to the activation side of the Trombetta but am not sure if there will be too many amps. I would do this just to ensure it's the VMM before I go through the headache of buying one. I have also swapped VMMs front to rear and nothing changed. I simply swapped them and didn't go through any procedure. I cannot find the installation procedure. Can someone guide me to it? Thanks

Terry W · 12-10-2017, 01:11 PM

Pat, When I was having VMM problems I swapped mine front to back and then back to original, the problem followed the bad one, I don’t believe there’s anything you have to do other than swap ‘em.

There’s a procedure for programming a blank one I believe it’s in the tech library, I have it somewhere if you’d like to see it.

FWIW, I tried to program my bad one from my good one and it didn’t make any difference.

Terry

swprdog · 12-10-2017, 02:22 PM

Thanks Terry: I have swapped mine several times and it makes no difference. It's back to the original positions now. Being that I bought this coach used maybe both VMM's are bad in that position. That's why I want to make a jumper to insure it's the VMM. I believe #19 on the front VMM has to do with the ABS system which probably wouldn't light until it detected a fault so if it's not working I wouldn't know.

JLMunsil · 12-10-2017, 02:38 PM

Switching the VMM’s is all you have to do. After the switch if the problem does not change than the VMM is not the cause. It must be the signal from the coach batteries or something else.
Putting a jumper from the battery to the solenoid is a good test there isn’t a problem with amps. The solenoid will click and the voltage on the chassis batteries will increase to equal the coach batteries.
Another check is, have someone push the boost switch and check if # 19 light comes on and the solenoid clicks.

swprdog · 12-11-2017, 04:34 PM

OK...several questions. I took apart the connection and inspected it and nothing looked abnormal, I took some voltage readings and things looked normal. I still want to repin it when I borrow the tools from a friend. I put it back together and swapped VMMs AGAIN. No change. I jumped from the house battery stud to the Trombetta and it clicked and the voltage readings equaled out. #19 light did not illuminate. Is that normal? I pressed the battery interconnect switch on the dash and heard the click and the wife stated she saw the #19 light illuminate. I looked the whole mess over and realized I have no idea where the charger input enters the system. My remote panel shows 14.6 volts and the batteries read 13.0 or less no matter where I took readings. Shouldn't they read the same? What if the Trombetta activation inputs(little studs) are backwards? I don't think it would make any difference, like any other solenoid.

Terry W · 12-11-2017, 05:06 PM

Pat,

I agree with your thinking on the relay, I don't think it cares.

You can go back to my post #42 and see my findings with the batt boost and #19 & #20.

If you want me to I can go out and jumper to the relay closing lug and see if it affects the #19 light, just say the word. I'm not sure how that might make the #19 light up.

Terry

JLMunsil · 12-11-2017, 05:32 PM

Running a jumper from the batteries is bypassing the VMM so #19 light should not come on. The stud wire locations don’t matter and given that you were able to get the solenoid to engage with a jumper it is working ok.
The remote inverter/charger panel voltage should be close to the house battery voltage. The charger voltage comes from the inverter/charger thru the large red positive cable to the batteries at the left rear corner of the battery bay while plugged into shore power.
Seems as though you are still not getting the signal for the house battery voltage. Everything else is working ok.
I appreciate your determination. Keep checking we are probably missing something simple that will explain or fix the problem.