Making interior lights run off aux batt question

[westy87]

So true, Mark. With my memory that could be me! I see your logic and I picture how you did it and how later you would not need a memory like a steel trap to return your wiring back to original. Good thinking! I guess I better start labeling, documenting, marking, etc.
I appreciate your insightful comments.

[crazyvwvanman]

I agree, hardwired has advantages if done safely. Problem is, people don't always follow the exact way the guy who did it safely tells them about. Attaching to the back wiring such that fuse #3 would bridge the 2 batteries if later installed is a potential problem waiting to happen if only a remote long term potential one.

Clean is in the eye of the beholder. A solution that requires no modification to factory wires, is visible immediately upon inspection, and can be undone in 30 seconds is surely cleaner than a hidden, undocumented, possibly problematic one.

Mark

[tencentlife]

Yeah, Marks method is very simple and straightforward but it's not as clean, nor as secure, as hardwiring in behind the dash or, my choice, going direct to the cig lighter. If the wire slips out of the fuse socket then there's a hot lead on the loose; a wire tie would prevent that happening. When you want to work on the panel it may be in the way, and if you want to pull it to get it out of your way, it has to be kept isolated since it's hot. And there's the appearance question; that matters to some, not to others. In the end there's more than one way to skin a cat and that leaves people different choices, which I say is always a good thing.

One thing is that nowadays the cig lighter socket, which was designed for short-burst high-amps usage, has turned into a power supply, with potentially higher and more sustained usage than originally intended. It's not realistic to use more than about 20 amps briefly, and 10-15 sustained from a cig lighter plug, but 15A is a 180watt inverter, for example; some people might plug one of these into that socket and leave it on for hours. For that kind of use I would feel better with a hardwired connection. Of course one can say "then don't do that", but I design for potential, not restrictions. Who knows what someone will do down the line, and even if they're warned against doing something they'll do it anyway. Consequently, I'm Mr. Overkill when it comes to wiring.

[westy87]

Both of you guys have given me useful and do-able options! Mark, I think I'm leaning towards scotchloking to B11 just for appearance sake, putting my connection behind the panel instead of in front, though I know the results would be the same. My harness is exposed, the plug is pulled, and it looks easy and straightforward.
Tencent - thanks for the confirmation and the additional info. That will come in handy when I install my lowrider undercarriage neon lights!

[crazyvwvanman]

The simple and safe approach is to pull fuse #3. Then plug a male spade into the bottom leg hole where fuse #3 was, with a wire leading to there from the aux battery power. This will move everything that WAS on fuse #3 to the aux battery instead. Any time you ever need or want to go back, pull the wire with male end out of #3 lower hole and put the fuse back.

Be sure to put a fuse on each wire from the aux battery +

Mark

[tencentlife]

You read it right. There are lots of unused pins on the back of the panel. You can see them all along the bottom edge of the box area on the top of the page in the late wiring diagrams. They could be tapped into for various reasons but the problem is having the right bullet connectors to do it for the ones that are included in the big multi-pin connectors. There are some others that are just exposed male spades on the back of the panel, and those can be used for various things. Here's a list of those and what they do (applicable only to the late panel with push-in fuses, late'85-on):

When you want a power supply for something, there are unused pins on the back of the main relay panel for most anything you'd need. On the left end (installed position), there are 6 pins in two rows labelled "P". These are all #30 pins, battery direct, unswitched, unfused. They are good for fairly heavy consumers. At the other end are ten pins labelled "G". These are hot under various conditions and can be used to power accessories. You can patch into the panel at whichever pins do the job for you by just plugging on a female spade terminal. It is always advisable to use a fuse inline from any power source to protect your device and wiring.

I'll list them according to the diagram. Where power is via a panel fuse, I've noted that with the letter "S". Always verify with a testlight or VOM before hooking up:

G1 & G3- X-bus load-controlled power (hot when ign. on, goes cold when starter operates) via S12
G2 & G5- #15 ignition-switched power via S18 (this is the ideal power source for extra instruments)
G4- D+ (alternator trigger circuit) via alternator warning LED
G6-dead end
G7 -headlights power
G8 -dimmer-controlled panel lighting power (to light your extra gauges)
G9 -parking lights power via S20 (for your low-rider under-chassis lighting, ese!)
G10- hot when windshield washer pump runs (headlamp washers, anyone?)

Earlier panels with stick fuses may also have extra power pins on the panel. You can check with a testlight or VOM.



E3 is common with B11 and B12, but I see on that diagram it is shown as a small pin. Since the cig lighter is a fairly high-amp load, you're probably just as well off tapping or splicing into B11 with a wire of the same or larger gauge from your aux battery.
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[westy87]

I'm planning to scotchlok the 14AWG wire from B11 to my new fuse panel and then pulling fuse #3. That seems to be the easiest approach.
My question concerns the diagram in the Bentley - page 97.68.
My first thought was to patch into E3. I think I got the correct connector (E - multipoint connector (black) for main wire harness), but I noticed there is no wire feeding E3. Am I reading this Fuse/relay panel diagram correctly?

[tencentlife]

Yes, you should have a fuse on your aux battery feeder, positioned as close to the actual battery positive pole as is practical so the whole feeder wire is protected from shorting due to inadvertent physical damage along its route.

If you are putting the cigarette lighter on your aux feeder along with those other smaller loads, then at minimum your wire should be 12ga, but 10ga is much better. To protect the wire and loads on it, I would keep your fusing at not more than 20A, 15A will probably work fine.
_________________
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Please don't PM here, I will not reply.

[John Sullivan]

Yes you need a fuse for the AUX wire in the aux box if you are either splicing to the pink wire or using the "plug in lower leg method". Either way you will be removing the 15 amp S3 fuse, so this needs a new 15 amp fuse in series with the new wire from the aux battery.

[KayAych]

Thanks for all the help, I've pulled off my (1981) Westy fuse box and see exactly how to re route the fuses. Next question is, what size wire should I run from my aux to the fuses? And does it need a fuse itself, or is that redundant since I'm connecting to the fuse box?

[Vanagon Nut]

[crazyvwvanman]

An even cleaner and simpler way is to plug the aux battery power feed into the lower leg hole where fuse 3 was pulled from. No need to splice in the back at all, no need for a dummy fuse. You can quickly put those things back on the main battery if the need should arise simply by pulling the feed wire back out of the bottom hole and putting fuse 3 back in. This has worked for me for 10+ years in my 87 Baja Syncro.

86-91 only

Mark

[John Sullivan]

I did exactly what Tencent recomended in his last paragraph,

"Or, run a 14AWG wire from the new fuse panel, and patch it into E3, in the black multi-point connector on the main panel. Remove fuse 3. This will feed the interior lights, clock, radio, and cig. lighter via the OEM wiring. Fuse 3 must be removed to isolate the batteries, and therefore you must have fuse protection on the feeder from the aux battery, i.e. your new aux fuse panel. I like this approach the best. If you can't handle the E3 patch, you could Skotchlock your feeder to B11 right behind the main panel. Electrically, this is exactly the same. You must still remove fuse 3 in this case to keep the batteries isolated."

I have a new fuse 15A and fuse panel in the Aux compartment (for the AUX Battery) and ran a wire 16AWG to the Pink wire B11. I used a 2 wire splice and did not have to cut anything. Removed the fuse S3 and blocked the holes with a dummy fuse (so labeled). This is a very simple fix and moves all the interior lights and the front cig lighter to the aux battery. It is also very easy to change back to the original configuration.

This has worked well for 2 years now.

[glutamodo]

By the way, if you hadn't noticed, those pages from the 80-81 Vanagon wiring diagrams are available on theSamba's wiring diagram Archive page, look down at the bottom:

http://www.thesamba.com/vw/archives/info/wiringt2.php

[Vanagon Nut]

And to be clear... (though Mark explained this)

I disconnected the power coming from backside of S9 to backside of S7.

Power to S7 (now my interior light/radio fuse) comes from aux battery.

S7 became available as I had no need for the silver socket.
_________________
1981 Westy DIY 15º ABA
(VW Gas I4)

1988 Westy DIY 50º ABA

VE7TBN

[Vanagon Nut]

[KayAych]

Thanks a million you guys. Mark, in order to check to see if what Neil says IS true... which poster is Neil?

[crazyvwvanman]

If what Neil says is true on your van, fuse 7 may have a wire to the top of it already. Make sure there is only one wire at the bottom, and none or one wire at the top. If the top feeds the silver socket on yours you can unplug it and tape it off unless you need the silver socket for something. Also unplug the big red on the bottom end of fuse 7. Then my earlier proceedure should work for moving the stuff from 8 over to 7.



Mark

[crazyvwvanman]

Different early years have different options for doing this. Remove the negative terminal from all batteries while working on the wiring.

I don't have access to an early aircooled at the moment to check but it looks like fuse 7 is not used in your 81 van. If you look at the back of the fuse panel you should see a single big red wire to the bottom side of fuse 7 but nothing connected to the top side. If so, you can unplug the red wire, COVER IT, and then plug a power feed wire from your aux battery in where the red wire was. Then move the wires from the top of fuse 8 over to the top of fuse 7. Fuse 7 will now be your interior lights, cig lighter socket, and your brake lights. The wires on the top of 8 now should be 2 smaller reds and a red/yellow strip. The smaller of the reds is the interior light wire and the slightly larger one is the cig lighter wire. The red/yellow stripe wire is the brake lights.

You could cut the brake light wire free from the red one if it is combined in one end and then put a new end on it and put it back on top of fuse 8 so the brake lights won't be on the aux battery. This would leave the brake lights alone on fuse 8.

All power wires feeding from your aux battery should have a fuse on them right near the aux battery. Do not skip this! 15 amp should do.

Mark

[Vanagon Nut]