Click and... no 12v power anywhere (1976 D26 Brave/440) - Solved!

[Mosin]

Greetings all,

Long time since I've been stumped and unable to find a solution via forum search, which is a testament to the invaluable aggregated knowledge here! The recent "Click - No Start Again" thread describes a similar condition but Pandora's new glitch has an added twist that has me stumped.

A bit of relevant background: last month before an outing I brought my fully charged 12v battery to the rig (which is started and/or driven at least every two weeks) and was surprised when I turned the key, heard a solenoid click, and then experienced a complete "No 12v Power Anywhere" condition where the engine wouldn't turn over, and there was no power going to the lights, the backup camera, or any non-key enabled 12v accessories. It was as if no battery was hooked up or the battery was completely dead. I briefly went over the wiring and looked at the relays, and nothing looked burnt/amiss. Grounds are tight as always. Strange! Sure that the battery was fully charged, I removed the positive cable and replaced it, and once again, power returned to the 12v components, the panel lit up when I turned the key to the first position, and the rig then fired up on the first try. It was disconcerting since I never figured out what was going on, but the rig started and drove fine for the weekend trip to Joshua Tree. FWIW the point of that background is that this exact condition appeared temporarily a few weeks ago but went undiagnosed. In the interim the rig started and drove perfectly.

Today, the same condition returned, yet this time it isn't magically going away (go figure) and Pandora is stuck. As before, after hooking up the freshly charged battery all of the 12v accessories/components work (eg. backup cam on switch, the ignition key in pos. one lights up the dash panel and the 12v fuel pump turns on, yet the moment I try to start the engine there is a distinct solenoid click, and then all 12v power is lost (no lights, no backup cam, no fuel pump, no ignition click) until I unhook the battery and reconnect it, at which point the 12v accessories work again. <== THIS is why I am especially stumped, because I am unaware of a single component (besides the 12v battery itself) that gatekeeps all 12v accessories as well as the starter, such that its intermittent functioning or failure would lead to the condition I am experiencing.

To pose my conundrum in the form of a question: what component's failure could produce a condition where on initiating startup all 12v power from the battery is cut off to both starter and accessories until the battery is disconnected and reconnected? Again, the rig will subsequently fail to start and go completely "dead" when the key is turned to the second position.

Two last points: the battery is fully charged, tested good, and was supplemented by a jump starter for good measure. Battery cables are virtually new, and grounds are tight. I will check and double check again (I'll be taking a different battery over tomorrow and going over wiring/grounds again for the heck of it) but these do not seem to be the culprits.

Thoughts? 

Thanks!

Dave

[RockwoodMike]

Where is the main cable ground being bolted to? The frame or the engine?

If the cable is to the engine, then there needs a good cable back to the frame..

In essence the engine is insulated because of the 3 rubber engine and transmission mounts..so there should be a cable from the engine to the frame to counter that insulation..

If the connections are good on the cables everywhere. it doesn't mean they are making good contact..A full removal of each cable to clean and create good contact is the only way to be sure..

Moisture will get everywhere causing corrosion..and it may look like a good contact, but it really is not 

[Mosin]

The main ground cable from the battery runs to a post inside the battery compartment, where it meets a ground cable extending to the engine, which is itself then grounded to the frame (thus, three ground wires and three connecting points). I'm about to go down and try a different battery, so I will be sure to remove and clean all of the grounds, even though they are looking clean and feel tight. Many thanks for the response!

[RockwoodMike]

Another point that could go bad is the connection of the copper cable to the end fitting..The thing that is crimped or soldered to the cable..Sometimes that connection can become loose from vibration

[Mosin]

It was the battery    Since it's 105 today I mustered a basic finger-tight test of grounds (all good, looking clean) hooked up a known good marine batt and blammo, 440 heaven!

Not sure why a 2-year old battery that has been consistently charged/maintained, showed 13v on a multimeter, and subsequently checked out as "good" when tested by kind staff at point of sale would fail as it has (even in conjunction with a beefy jumpstarter), but apparently the curse of "Valuecraft/Autozone" strikes again! 

I will retitle with "Solved". Thanks for the replies Mike! 

[RockwoodMike]

To positive prove your solution in regards to the battery being bad..Put the bad battery back on and see if the problem returns..

I am sorry but I am not buying that your battery is bad....I think with you connecting and reconnecting cables, testing a different batteries is causing a temporary "good" connection..And that temporary good will let you down when it goes back to bad

[Mosin]

This is sage advise indeed and I will follow it and report back!

[RockwoodMike]

subsequently checked out as "good" when tested by kind staff at point of sale

When the staff at the Zone tested the battery, did they put a heavy load test on it..? Or just a volt gauge and a charger??

I have seen batteries that break internally when given a sudden heavy load such as a starter..And then "repair" themselves when they cool down..

[DaveVA78Chieftain]

Also, being nothing more than a piece of wire, the fusible links at the starter solinoid can create squirrly situations like this do to expansion and contraction from current induced heat (AND AGE).
The pin for the large red wire at the half moon connector (ign switch wires) at base of the steering wheel is also a trouble spot.  Had to jumper around it on my 77 Chieftain M400 when I had it.

[Mosin]

As Mike predicted when I returned with the Valuecraft battery the rig fired right up again. Several times. No issues whatsoever. Since the Zone staff did not do a load test before determining it was good I thought it probably had internal short/issues under heavy load, but apparently it is indeed good.

Thus, returning to wiring, I noticed that what I had thought was the ground cable extending from the battery compartment post to the engine block was in fact the 6v house battery ground cable.    Hence, the only battery ground I have had for the past decade plus for both 6v and 12v batts has been this battery compartment post, the sheet metal around which I am not even sure connects to the frame. After cleaning all posts and connectors I have now added a 4 foot ground that runs from the battery compartment post to the engine block, where another shorter ground connects the engine block post to the frame. Rig starts immediately with the Valuecraft.

Hopefully this will do the trick! Test drive tomorrow    Sincere thanks for the responses!

[Mosin]

Also, being nothing more than a piece of wire, the fusible links at the starter solinoid can create squirrly situations like this do to expansion and contraction from current induced heat (AND AGE).
The pin for the large red wire at the half moon connector (ign switch wires) at base of the steering wheel is also a trouble spot.  Had to jumper around it on my 77 Chieftain M400 when I had it.

I know these will bite me hard one day, so I just might replace at least the fusible links now. Are they easily obtainable?

[RockwoodMike]

6v house battery ground cable. 

Your house battery is 6 volts??

Good diagnostic on your part in regards to cable problem..

That is my worst fear in regards to motorhomes..Broken down in a campground..

[RockwoodMike]

I just might replace at least the fusible links now. Are they easily obtainable?

The Zone should have them..plus all the connectors to splice in the replacement..Fusible links really don't go bad..I have never had one go bad..

But there is nothing wrong having a spare to carry on the RV..Then if you really want to get deep, spare everything else you can think of..starter..radiator hoses..fan belts..etc..

If you do break down on the road, you will have a good chance of having the part in hand..