quote:

Originally posted by Rusty:
Keep in mind the speedo head might not be the culprit, but rather the circuit feeding it, which should be dead with the ignition off.

Supply this circuit to the ignition source. There might not be anything wrong with this. This might just be the operating voltage of said unit.

Good find on your part.

Bill N.Y.

So...wait are you guys saying I need to perform one more test? What are you saying? no power is feding the coach whatsoever during testing. The main power is disconnected at the front power distribution bar feeding all ignition circuits,alternator disconnected,both batteries disconnected,all power feeding starting circuit disconnected...Meter set for DCA hooked to one side on POS battery post and the other side of meter hooked to main power starter cable feed. NEG side of same battery is connected. When (2)Speedo generator power wires (feeding to guages) is disconnected-no change. When last wire is disconnected fron Speedo generator the 4DCA indicating on meter changes to Zero. Replace part will solve problem correct?

quote:

Originally posted by hilarlee:
...are you guys saying I need to perform one more test?

Replace part will solve problem correct?

Chances are, no. Look at it this way, why would the speedo pulse generator need to supply a signal when the key is off? You don't care that the coach isn't going anywere! So, why would it need voltage sent to it if it's not going down the road?

Find out what circuit is supplying power to it all of the time and put the voltage to that on a hot only with key on.

Bill N.Y.

Bill N Y are in harmony here - the problem isn't likely the speedo head (and if you check prices, you'll be much relieved).

The speedo head is merely a drain on a circuit that's feeding it all the time, and shouldn't be.

However, the way you've connected the test circuit actually reconnects the chassis battery into its normal circuit. BTW, this is a usual way of checking for leakage, so you done good on the procedure.

But yes, there's another culprit, but your efforts have further localized it, but not yet isolated it.

Thanks you guys for the explanation..."sigh"...I'm looking through my Barth Manual and found an "Installation and Operating Instructions For Dana's Electronic Speed Control (7R System)" The signal generator I suspected is part of this kit that allows you to set the cruise control from your left turn signal. I've never used the cruise control on the turn signal(always OFF)...the cruise control I utilize is simply a "joystick" mounted up on the dash (no manual found) that you can toggle up or down too turn on and off...Also whats kinda strange is this installation manual clearly states,
"this kit is designed for gasoline powered vehicles only"...maybe this system isn't even being used and can be disconnected? Do any of you '92 diesel barth owners have/use a left turn signal cruise control? Is the "Toggle" cruise control a seperate newer system someone added? Now I'm feeling lost..

I have the Dana cruise control and the control is on the turn signal stalk. I use it all the time. Maybe the reason it says for "gasoline engines only" is that there is no vacuum generated in the manifold of a diesel and it uses vacuum to pull the throttle cable, this is why we have a vacuum generator that uses the compressed air thru a venturi and is why the air system always goes down when parked. There are two vacuum generators one in the rear for the cruise control and one in front for the dash HVAC unit actuators.

HTH

quote:

Originally posted by hilarlee:
Now I'm feeling lost..

Get ready to feel more at a loss.

The pulse generator might in fact (probably) be a grounding (looped) circuit (insert Rusty's wiring terminology correction ) and your problem could be controlled elsewhere. All a pulse generator does is make and break contact via a magnetic field. You might even be able to jack up a wheel and turn it a little (with key off) and not have a drain or even less of a drain in the system.

See, the pulse generator sends a make and break signal back up the line to the speedo head. Your problem could be that the speedo head itself is wired wrong.

Try reading this post and see if anything looks or sound familiar. This is for the backside of a VDO gauge.

Pin 4 is key on hot 12 - 14 volts
Pin 7 is the 5 volt feed for sensor SPEEDO POS 24
Pin 8 is the speedometer pulse signal line SPEEDO NEG 23

While this is a diagram for a VDO gauge this should show your "minds eye" how the speedo is wired.

Bill N.Y.

Hey Bill, I'll check the wiring on the speedo according to your notes but does it matter that the speedometer has always functioned okay? How soon are you going to visit California?

quote:

Originally posted by hilarlee:
Hey Bill... How soon are you going to visit California?

Are you sending me a ticket? Use SWF as the airport code.

The problem with trying to diagnose anything via the web is the unknown factor... I can look at a lot of things and just know how it is wired.

Your problem sounds to Me and Rusty like there is a circuit that is powered all of the time.

I am using assumption and hunches. You could have some type of transmission interface or a cruise control relay that is really controlling all of this and that might be on the wrong power supply circuit.

You could even have a sticking relay (instead of the speedo) that is causing power to go to the pulse generator all of the time instead of when the key is on.

You'll have to play electro detective to track it down. The good thing is you've isolated it to a device/item. I would think somewhere in the dash area (or transmission interface area) you'll find some fuse that would kill all of this. Put that to the "key on" circuit of the fuse panel.

Do you have a wiring diagram you could fax/ e-mail me?

Bill N.Y.

Bill, whats your fax number? My following descriptions are taken from the Spartan motors "Circuit & Legend" One of the two wires (the other went to the speedo gen.) I disconnected from the start solenoid is a wire labeled, "Alternator Output #302"(Alt POS to Batt Pos or shunt) When I put one meter lead on the end of this wire I also see 4.2DCA. In my attempt to isolate I disconnected #28 IGN to REG (Alternator relay-feed power switched) Next I disconnected the ground and #59 ALT OUTPUT (Alt pos feed to cab batt selector sw or shunt)When I finally disconnect the last two wires from terminals 1 and 2 from the top of the alternator, the meter reads "ZERO". According to my schematic I've disconnected everything coming or going from the Regulator according to the diagram. I have a manual for the Delcotron 10SI and 15SI series, Types 116 and 136 alternator that indicates the solid state regulator is mounted inside the generator...my diagram shows #302 going to an external regulator...? Anyone have experience with the Powerline 190AMP Alternator on Cummins 6BTA? The problem seems to be pointing at the regulator. What I don't understand is my diagram shows wire #302 going from the start solenoid directly to the alternator regulator...but there is no #302 that PHYSICALLY is found at the alternator..Anyone? I can fax my wiring diagram to anyone that provides me a fax number tomorrow...this way I can highlight all the areas that I have isolated. BTW, Thanks everyone for not falling asleep on this one!

Try

http://www.hehrpowersystems.com/pdf/S25TS.pdf

for a manual on the Powerline.

Mike

You stated it was at the pulse generator for the speedometer, now it's at the alternator?

Now, I'm at a loss...

I'm going to go out on a limb here... your alternator is bad and should be replaced.

It seems that a diode inside of the alternator has shorted together.

A diode is nothing more then a "one way" check valve inside of the alternator. The diode will only allow voltage to go one way. If a diode shorts it will still charge at 14v but when off it will drain voltage down.

There are three diodes in an alternator. Each one accounts for 1/3 voltage. In a 12 volt alternator (14v) you will get 4.6 to 4.7 volts out of each diode, likewise if shorted, it will suck down about the same. Now if it's popped open you'll charge at 1/3 less voltage.

There are a lot of electronic items that use between 4 & 6 volts dc to run: a pulse generator for a speedo, a tach tap and some engine sensors use lower voltage.

The lower voltage, in most cases, does not come from the alternator but is produced inside of the items it's controlling.

Examples:
If the engine uses electronic sensors that run on 5 volts it will be produced by the engine's ECM.
A pulse generator for the speedometer running at lower volts will be produced by the speedo head.

If you have an engine tach some alternator allow for a signal wire to go to the tachometer. Some tachs get the signal from an engine mounted cable. Some also get the signal from an engine mounted tach generator.

I'm on vacation in North Carolina (yes, again) and will be back home on 7/12.

Another thought hit me. If you have an external diode tap coming from the outside of the alternator and your hooked to the wrong side of it that could explain a voltage drain.

On a fire truck I once found power draining because another mechanic had installed a new alternator and the hot feed wire was just touching the diode stud for the tach feed circuit.

At this point, I'm of the mindset that you'll need an alternator. With your batteries fully charged and the motor off I want you to touch the pulley of the alternator with a thick piece of metal and see if there's a magnetic pull. At 1/3 voltage it would be a little weak.

Don't go and replace your alternator yet, post more info and we'll go from there.

If you have a local alternator rebuild shop call them and ask if you could bring your alternator in for a check - explain what it's doing and see if the'll check it out while it's in the motorhome.

Bill N.Y.

Yeah Bill, I'm at a loss too. The lead for the pulse generator and the #320 Alternator output lead are both crimped together on the same loop connector going to the start solenoid. I cut the loop connector off to determine which wire was causing the problem..yesterday I tested the alternator lead and discovered the 4DCA at that point too. Both wires travel in the same loom...possibly an inductive connection between the two wires? I'll put everything back together and will try your magnetic pull test...what should it do if normal? I have one belt that snakes through all my pulleys...is it's removal as simple as torquing the belt tensioner in the opposing direction to remove? Then I can remove the alternator for testing...?

quote:

Originally posted by hilarlee:
Then I can remove the alternator for testing...?

No need to remove the alternator. Just touch the pulley while it's mounted to the engine. The flatter the surface that your touching the more of a magnetic pull your feel if it's backfeeding.

Bill N.Y.

Hey Bill, I removed the alternator earlier this afternoon and had Costa Mesa Generator repair test the alternator. I am told nothing is wrong with the alternator/regulator. The owner of the shop said the same thing you did about the wires being reversed on the alt... but even with the two leads disconnected I still show a drain. I put everything back to it's original state and will need to regroup. Aside from not knowing what I'm doing I think I've been chasing my tail because I've been leaving cables disconnected along the way. This has led me on a wild goose chase. I need to start over.

Does anyone know if this coach has an isolater and where is it physically located? 30' 92 190HP Cummins