Itinerant Air-Cooled

1977 FI Bus type IV motor.

I just replaced my alternator wiring harness and now, I can see the battery light glow when I step on the brakes, use a turn signal, honk the horn, hit the brights etc. While driving, even at night, I don't see anything until I tax the alternator in some way.

1. I have 2 other electrical issues but not sure they are relates. I have a hard start when it's cold but no problem when I come back out from the store and turn the key. I have the hard start relay installed and for some reason the fuse popped on Friday.

2. I went camping and my aux battery only lasted a day and it has always lasted 3.

The 70 amp alternator and the regulator are new (less than a year and a half old anyway) brand new braided ground straps and the contact areas have been sanded. I am running 2 stand alone "Kicker" speakers and an inverter from the cig lighter for my Sirius stiletto radio.

Is this a non issue and unrelated to the others? I have never seen it glow like this before with the last 2 alternator wiring harnesses, the original one and then with one for a '78 Bus.

Take a reading on your voltmeter without and then with auxilliary device or brakes.

I had similar thing on my Volvo which turned out to be a belt that was too loose....would perform fine, until an extra load was put on it.

12V with key in the on position, 13.75ish idling and no change under load. I removed and inspected the alternator belt and thought I had a spare but it was for a type1 motor. I tightened the sh!t out of it but the symptoms are the same, the light gets brighter with everything I add the the load.

Check the B+ terminal at the starter.

This isn't late Bus specific, really, but sometimes you get something going on like this:

I'll take a look tonight. Thanks!

James Dwan wrote:
I tightened the sh!t out of it but the symptoms are the same, the light gets brighter with everything I add the the load.

James? You untighten the sh!t out of that belt IMMEDIATELY. The new modern era bearings HATE tight belts. You should understand that you must apply a filter to all the help you you are going to get when you ask a question online. For example, one poster might mention that his Volvo had the same problem, and he fixed the symptom by tightening his belt. Well, that might work for a Volvo with an integral regulator and a water pump running with the belt. But we Type 4 engine owners have the easiest belt life of anyone. It is the only engine (and this includes the Type 1 engines that actually have a bit a work to do spinning that fan) I know of whose belt has only one job to do, to spin a maybe 70A alternator. If your belt is intact, it is working. Only an oil soaked belt working with a broken alternator mount can get near to diminishing your charge (I think you and I actually did have to deal with that).

I think you do have an interesting issue going on here, particularly with the degraded auxiliary battery performance, but you have to be scientific here. Start your diagnosis with getting both batteries fully trickle-charged. Then see, that very night, if your charge light reacts to consumers. If not, then you know the electrical system is good, but you have a slow discharge process going on where the alternator is not staying on top of its chores. You need to double check for a slow discharge at the negative post-to-negative cable with your ammeter with both batteries. Check for full isolation between both batteries when engine is off.

If everything checks out, I would double-check the red/white "big" wire at the starter solenoid. It goes to the fuse box. Clean shiny, snug but not stupid tight (James . . . I am serious, do not tighten the sh!t of things!!), and check where it goes to the fuse box (please disconnect negative termional at battery first). Clean and make sure that the terminals are not damaged or loose-fitting. Then go to fuse #12, clean terminals, stick in a new fuse and look for the black wire that leads to the dashboard cluster. It supplies 12 volts to the alternator light shell. Finally, the blue wire at the alternator warning light also supplies 12 volts to the same light (that is what makes it go out when the engine starts). WE DO NOT KNOW WHICH WAY THE CURRENT IS FLOWING when the light glows! Either it is the system dropping down (through the black wire) or it is the alternator output not coming up under load, we don't know. That is why we have to do all of this dorking around. There are grounds up front that must be good too. The ground strap between the transaxle and the diagonal arm bracket, you said it is good, I believe you, both sides. How is the ground for the auxiliary battery? Do I remember or only hallucinate that you are using the left battery as the primary because it is a nightmare of cables in there and the right battery is a big tall monster that couldn't fit under the spare tire well?
Colin

Ha ha! I didn't tighten the sh!t out of it. I knew I'd ruffle your feathers. I remember your scornful rebuke and the hairy eyeball when I claimed I did that one time
That's a long list list that I will try to tackle Friday morning before I leave town @ 09:30 and report back, probably next weekend.
Yes the auxiliary battery is on the left.
How do I "Check for full isolation between both batteries when engine is off?"
The fuse box is a likely culprit because I have a parcel tray so the fuse box is sitting on the netting and my son used to grab the frame to climb in and out of the bus until very recently. He uses the steering wheel now =D>
Thanks!

James Dwan wrote:Ha ha! I didn't tighten the sh!t out of it. I knew I'd ruffle your feathers.

How do I "Check for full isolation between both batteries when engine is off?"

Feathers . . .

Tester between (+) Primary and (+) Secondary should be 0 volts.
Now put a load on the Primary (headlamps). If voltage is still 0, both batteries are involved. You should read 1 or 2 volts differential.
Start engine. Now both batteries should have same voltage to ground and 0 between them.
Chicklin