Electrical Panel - Engine

Bill Stephenson · July 10, 2012, 12:51:00 PM

I am in the middle of troubleshooting the following:

1) why after I start the engine it runs smoother and at what sounds like higher rpms if I turn the start switch off.

2) why my engine gauges are not working. (the tachometer, fuel level and temp don't work at all; the voltage gauge works with the start switch on but once I start the engine and turn the start switch off it then does not work)

I have a 1988 and last year I upgraded the electrical system with a dedicated starting battery, a four golf cart battery house bank, echo charger, etc. (basically everything Jim Moe recommended except for the alternator upgrade). At some time later I noticed the above two problems. I don't think they were related to the upgrade.

So far I have traced all the wiring at the engine to the harness and checked those connections and have removed the engine panel and checked those connections. With the starter switch off, each gauge shows 13.1 volts from the power source to their ground. So, I assume that individual gauges grounds are satisfactory. With the starter switch on each gauge shows 13.1 volts from its lower pole to its ground. So, I assume that each gauge has power.

That's as far as I've gone and I am not sure what the next steps are. Any advice or direction will be appreciated. I am considering the wiring harness upgrade but I am not sure that it would solve my problem.

Bill

Ralph Masters · July 10, 2012, 02:03:02 PM

Bill,
When you turn the key switch "on", it provides the power to the electrical systems that power the tach, fuel and temp gages. When you turn that switch "off" you turn off those systems. That is why they don't show any reading when the engine is running with the switch "off".

Ralph
Ciao Bella

prh77 · July 10, 2012, 02:14:33 PM

Also, when you turn the switch off, that cuts out the alternator which will make the engine seem smoother and raises the RPM.

Ralph Masters · July 10, 2012, 02:22:30 PM

Unless the AO is wired directly to the battery or the 1-2-all-off switch, then it keeps pumping juice to the battery. As it should be.

scotty · July 10, 2012, 10:31:21 PM

I've been told not to turn off the engine switch with the engine running because it would damage the diodes. Is this a true statement? Thanks.

Stu Jackson · July 11, 2012, 06:21:35 AM

Scotty, no it shouldn't. The reason is that the ignition switch only turns the regulator on or off. What you never want to do is to interrupt the AO, which is one of the reasons we suggest it get rewired from the switch directly to the house bank.

Quote from: SD Diver on July 10, 2012, 02:22:30 PM
Unless the AO is wired directly to the battery or the 1-2-all-off switch, then it keeps pumping juice to the battery. As it should be.

If the regulator is turned off the AO stops.

scotty · July 11, 2012, 07:21:13 AM

Thanks Stu. (sorry for such basic questions, but...). What is AO? and how would it be interrupted by the switch?

Stu Jackson · July 11, 2012, 08:00:54 AM

Scotty, time to go back to basics.

You might remember the "Electrical 101" topic that IIRC you contributed to. AO is alternator output. In the OEM installation, the AO went to the C post on the 1-2-B switch. Our recommendation is to relocate it to the house bank and use an echo charger to automatically charge the reserve bank. Sound familiar?

The old and new alternator and regulator wiring diagrams are listed in the "Electrical 101" topic, too. They're here (http://c34.org/bbs/index.php/topic,4548.0.html), and show the ignition switch wired to the regulator. The ignition switch tells the regulator to turn the alternator ON by telling it to put out power. That power goes out via the AO. Turn off the regulator and the power stops. Interrupt the AO and you fry the diodes.

lazybone · July 11, 2012, 09:44:51 AM

Quote from: Stu Jackson on July 11, 2012, 06:21:35 AM
Scotty, no it shouldn't. The reason is that the ignition switch only turns the regulator on or off. What you never want to do is to interrupt the AO, which is one of the reasons we suggest it get rewired from the switch directly to the house bank.

Thank you for clarifing that Stu.

scotty · July 11, 2012, 12:09:01 PM

Thank you, Stu.

Ron Hill · July 11, 2012, 02:30:37 PM

Guys : Never say Always !

I seem to remember that the old AutoMac (Automatic Alternator Controller) got its battery sensing from the key switch! That's why the Auto Mac wouldn't function with out the wiring harness upgrade!

So unless your voltage regulator also gets its power from the key switch, turning off the key switch with the engine running could present a real problem.

I also seem to recall that the old Balmar BRS I volt. reg. got it's battey (voltage) sensing from the key switch - don't recall where it got its power from??

Basicly, there should be no reason to shut off the key switch with the engine running, unless you are tired of looking at what the 4 gages are reading !!?!

A thought

Bill Stephenson · July 12, 2012, 07:08:55 AM

Thanks guys for all the dialog and input. It does make sense to me now not to turn off the ignition switch once the engine is running. This weekend I will recheck the rewiring I did last year but I am almost positive that the AO goes directly to the house bank.

I still have the problem of the gauges (except for voltage) not reading anything when the ignition switch is on. Any thoughts here.

Bill

Ron Hill · July 12, 2012, 03:43:30 PM

Bill : Let me try again:

It isn't where the Alt.Output goes to that is so important, it's where the Volt Reg get it battery sense from and where the VR gets it power from.

A thought

Stu Jackson · July 12, 2012, 06:21:49 PM

Bill, as I understand it your issue is you have no power to the panel, and you're wondering where it comes from, right?

I actually don't know.

Years ago I had photographed the wiring behind my panel, in the port locker, in the lazarette and behind the panel. It is one of the few mysteries left to me to admit to.

But as I recall, when I turn the 1-2-B switch on, the cockpit panel gets power. It could well be that the panel itself is only energized by the ignition switch, but in order for that to happen, there HAS TO BE power going from the switch to the panel.

Now, from a completely "let's play detective" approach, it can come physically two ways: 1) switch to cockpit panel from behind the nav station electrical panel up above the small black sliding doors above the nav station, over the head cabinet through the port locker to the panel, or 2) via the power wire from the C post of the switch to the starter and then through the wiring harness to the panel. I say two ways, 'cuz i just haven't seen any other wires that could "qualify" as being from the switch to the panel. I didn't recall seeing any in the port locker when we redid our exhaust hose recently, however, I wasn't looking for it.

Yes, Ron's right about the sense wire, but it may have no impact on your issue, which is power, not alternator output, right?

So what I'd do is find the main power wire AT the panel. Then trace it back to see where it goes.

In order to help you figure it out, you may be interested in these links

1. Alternator regulator wiring - it mimics some of the wiring diagram in the next link, too http://c34.org/bbs/index.php/topic,4548.0.html

2. The Wiring Harness Upgrade in the wiki has a very good wiring diagram of the cockpit panel. One of my sketches kinda copies that. http://www.c34.org/wiki/index.php?title=Engine_Harness_Upgrade

I'll do a little more sleuthing on my boat, but won't be there for over a week. In the meantime, figuring out how the power gets there would be a start. Also, many times bad connections in electrical systems do just what you describe. You could run a temporary wire from the batteries or the electrical panel to the cockpit panel and see if it does work. If so, then finding the culprit gets somewhat easier. Jumper the key switch. Check everything.

You also wrote: I am considering the wiring harness upgrade but I am not sure that it would solve my problem.

You must be aware of the dangers of the connections for the old harness and perhaps the Critical Upgrades warnings about it. If the power does come up through the harness, what's your guess on this one? At the very least, check the connectors, 'cuz it's usually not the harness "wires" themselves that go (mine are 26 years old) but it's the danged connectors. You don't have to replace the entire wiring harness, but you do HAVE to replace the connectors. The warnings on the CU page should be enough, we hope.

You also wrote: ...last year I upgraded the electrical system with a dedicated starting battery, a four golf cart battery house bank, echo charger, etc. (basically everything Jim Moe recommended except for the alternator upgrade).

Since you didn't change the old alternator, did you remove the short wire connector between the alternator and the starter?

Good luck, please let us know what you learn.

Quote from: goosechase on July 12, 2012, 07:08:55 AM
I still have the problem of the gauges (except for voltage) not reading anything when the ignition switch is on. Any thoughts here.

This was written in the vein of "this is what I'd do if it was my boat." You reported you had power to the cockpit panel gauges, so if they only go off when you turn off the ignition switch, then the earlier answer is correct.

So, I'm confused between your original post and this later one. If this is the case, then it's kinda gotta be the harness connectors.

Bill Stephenson · July 13, 2012, 01:48:38 PM

Ron the Stu,
Thanks for the replys. I will do some more digging this weekend and let you know.

byw: I do have power to the panel and to the gauges as I said initially "With the starter switch on each gauge shows 13.1 volts from its lower pole to its ground. So, I assume that each gauge has power."

Another question. Is the power to the panel fused in any way. I have some sort of small black box behind the panel (about 1" square) that wires go into and out of but it does not look like a fuse in any way. I'll look closer at this over the weekend.

Thanks,
Bill