HELP! Electrical Problem

Fred Mc · September 12, 2017, 06:09:09 PM

Thx Tom

Do you have a make or model or oart# or???

Fred Mc · September 15, 2017, 07:23:37 PM

Well, I solved two of the 3 problems . An adjusdtment of the reverse solenoid linkage let me back up and a new Bendix Genenor let me air up.

BUT,

I still have the problem of the generator charging(or not charging the batteries)
I ordered a new circuit board from Luke but it still won't charge.
How can I test to see if the generator itself is putting out a charge?

Should I be able to get a voltage reading at the regulator?

One of the benefits of this exercise is that the voltage regular has now been moved from the baggage compartment to the old battery compartment so at least I can now get at it.

Its a GM PD4106 12 volt .
Thanks for any help

Regards

Fred

gumpy · September 15, 2017, 09:08:26 PM

Have you tested the voltage at the sense terminal of the regulator? I had to replace my regulator several years ago, and they sent me a new solid state regulator. When I got it hooked up to the original wiring, it would fluctuate terribly. I ended up having to run a new wire for the sense terminal directly from the battery. Something in the original bus wiring was causing a problem with the sense voltage. When I connected directly to the battery, it was rock solid and has been for 11 years now!

richard5933 · September 16, 2017, 04:37:04 AM

I agree with checking the wiring to the regulator. If the regulator can't get a good reading on the batteries then it won't send a charge. Ditto on the ground wires.

When I had the interior out of mine and was able to look through the inspection/starter window I realized that there are battery cable posts all over the place. The factory setup apparently didn't use straight runs of cable, rather they used lots of shorter lengths joined at the posts. Check each of these for good connections. By check, I really mean take all the wire lugs off the post, clean with the abrasive cloth of your choice to show clean metal, and then put back together tightly. While you're there, you might want to inspect each and every battery cable lug to ensure that they are still tightly in place and show no corrosion. I've discovered that it's necessary to inspect thoroughly to catch corrosion on the inside of the lug, not just for the crusty kind on the outside that's easy to see.

Same for the places the ground wires mount to the body and to the engine. Get your hands on each of these and check them over.

More than one of mine looked fine from the outside. They were tight and I assumed things were okay. But, when I opened them I found a thin layer of corrosion between all the many layers - more than enough to stop electrical current from flowing. Once on my forklift I had a no-start situation. Terminals all looked great and were tight. When I took them off, I found that the positive terminal had a layer of build-up which can best be described as scale. Once it was removed things were problem free. Problem appeared suddenly, but probably had been building silently for some time without my knowledge (or permission.)

Remember - block the body of the bus well before getting under the back end to check all these connections.

Richard

bevans6 · September 16, 2017, 04:38:08 AM

As Craig says, check the 12v wiring to the regulator. When running, check the voltage on the field terminal, should be some voltage there. To check the alternator for a test, jumper 12 volts to the field terminal briefly, check the output voltage, should spike fairly high.

Brian

Fred Mc · September 16, 2017, 02:46:12 PM

Success! Well maybe.

I discovered that the positive terminal on the regulator , which is connected directly to the battery was dead. So, when I jumpered it directly to the battery, it sounded like the generator was working as the engine speed slowed slightly and the "no charge" light on the dash went out and the voltmeter showed a voltage of 14.5 (note, I had adjusted the "pot" on the regulator previously so may have it set too high). Also when I put a test light on the field terminal of the regulator I got a pulsating light.

However, the a/c/heater motor would not come on (not that I need it)but this generally didn't come on until the "no charge" light went out.

Any comments?

Thanks

Fred

Fred Mc · September 16, 2017, 04:47:26 PM

I also notice that when the engine is turned off there is a 3 amp draw from the regulatorvto the battery.

bevans6 · September 17, 2017, 03:46:13 AM

usually the no-charge light and the AC motor are controlled by the relay output of the alternator going to a control relay. The same relay controls both things. There should be virtually zero draw from the regulator when the engine is off, 3 amps is way too much. Maybe on your bus the stock setup controls the power to the regulator through a relay, so it only gets power when the engine is turned on, and you've bypassed that?

Fred Mc · September 17, 2017, 06:32:42 AM

`The wiring diagram shows a direct connection from the battery to the pos term. of the regulator. When I checked that there was no reading at the regulator so I ran another wire from a hot terminal in the battery compartment. However I then can measure a constant draw even when the engine is shut off. And when I put a test light on the field terminate it constantly flashes.