Chassis and House dis-connects/Gremlins

Question

Let preface this by saying I'm having some electrical issues right now and I've done some due diligence in an effort to discover the issue. My full dive into this whole mess was primarily brought on by a Low Voltage issue to my Allison HD4060 Trans. I just have this sneaky feeling one issue is causing all the others.

Now for my first of many inquires regarding my dis-connects! The batteries are as follows, one 8D Chassis battery(load tested this morning) and at this time (4) 6 volt house batteries. Probably as most know, when you switch a disconnect it generally responds smartly and my house disconnect does, BUT my chassis disconnect lingers and slowly fades off(not really quite off but very very dim). I've had this issue before and somehow it corrected itself but for the life of me, I don't have a clue as to how that happened.

I could go on forever but I'll stop with just this question for now. I have checked the disconnect solenoids and their respective fuses, I've had my 6 volts disconnected at the batteries so I know there is No back feed through them. I've replaced and/or cleaned as many ground connections I can get too. I'm intending to replace some positive battery cables as I write this novel using 2/0 wire. I'll keep tinkering but maybe someone has had this fading disconnect issue before and can point me in the right direction?

enblethen · Answer

I would be checking the negative cable as well as the positive.
Make sure that the new cable is multi-strand. More strands the better! QWelding cable works.
Remove the sheath off some the cable. Look for blacked copper.

acampingwewillg · Answer

I'm under the bed now as we speak(engine access), I'll be cleaning up the grounding lugs with a wire brush/Drill wire brush and since I'm there, I'll make up some new 2/0 grounds from the batteries. I've also added a new ground lug just for kicks to be absolutely sure I'm getting a solid ground. As this is a 96 motorhome and after reading the actual build sheet/comprehensive owners manual, I have found that most wiring has been done with 2/0 cabling and here I though I was upgrading it.

bfl13 · Answer

There is a chassis battery disconnect switch, that operates a solenoid for the engine battery, and it is "slow", so what is the mystery?

The solenoid is "slow" and needs to be replaced. Or don't I "get it" ? I know some solenoids need to be tapped with a hammer to get them to snap over. Yours is just gummed up, but will still go over eventually. Or just soak it in silicone spray to loosen it up?

ca_traveler · Answer

Have you connected a good DVM across every pair of studs associated with a wire to check for excessive voltage? - Note Studs not Lugs. Or connect the DVM to a good frame ground and the voltage to the negative battery post should be very close to 0V and then the positive post 12.7V (charged battery) and work your way downstream to the solenoid and beyond.

Cleaning all the connections is good maintenance but the problem may be elsewhere.

It could also be a poor connection between any lug and the wire - corrosion or otherwise that you can't see. Cut off any covers and a visual check might be revealing.

Have you tried to parallel jump each wire? Even heavy duty battery jumper cables might help to isolate the problem. Be very careful about what you are jumping.

acampingwewillg · Answer

BFL13 wrote:There is a chassis battery disconnect switch, that operates a solenoid for the engine battery, and it is "slow", so what is the mystery?  The solenoid is "slow" and needs to be replaced.  Or don't I "get it" ?   I know some solenoids need to be tapped with a hammer to get them to snap over.  Yours is just gummed up, but will still go over eventually.   Or just soak it in silicone spray to loosen it up?Lets see, I once before had a fading disconnect but it somehow, corrected itself so I know it should not be slow and it should work as the House disconnect does "quickly". If I thought a simple replacement was all it needed, I'd spend the 40 bucks and do it(and I may just do that) but something tells me its all inter-related. Last time this happened, I believe I had a shorted battery hence, that's where I started since many times that's a good starting point. Bottom line is a I think there is a cause and effect other than a bad solenoid...that would be too easy. LOL :-)  Anyways....a tap or two can't hurt, Thanks for the thoughts.

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Chassis and House dis-connects/Gremlins

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