Purple Wire voltage confusion

[Alumarine]

Hi there,
I did a search on "purple and voltage" and read through 7 pages without finding an answer.

I was installing a temp/oil pressure alarm under my dash and was checking voltages.
I've run the black lead of my tester to the negative post of the battery.

On the BAT terminal of my ignition switch I have 12.5 volts.
On the IGN terminal with the purple wire I only have 11.6 volts when the key is in the run position.

I disconnected the Purple wire at the alternator with the same result.

When I disconnect the Purple/Yellow and faded Pink??? from the positive side of the coil the reading on the IGN terminal goes up to 12.4 volts.
The Purple/Yellow and faded Pink??? wire are crimped together on a ring terminal that looks factory.

Is this normal? The boat runs perfect and I wasn't looking for trouble.
thanks

 

[GA_Boater]

Tap the motor over a couple of times if you have a points motor. The points may be closed so there is a draw through the coil.

 

[Alumarine]

Brilliant, thank you!

I took the cap off and yes, the points were closed.
I put a nylon tywrap between them and the voltage went up to 12.5.

That also solved my next problem which was why I only had 5 volts at the coil.

Now I can carry on with what I was originally trying to do!

 

[Bt Doctur]

because its going thru a resistance wire to get to the coil , with a points system and the correct coil all you need is 7-9 at the coil.That is for coils that need a external resistor, some coils are internally resisted and use a full 12v at the coil

 

[Scott Danforth]

The starter "i" terminal provides full 12 volts to coil during cranking when you have points

Otherwise the balast resistor or resistor wire provides about 7-9 volts when the motor is running (about 6 with the motor not running)

 

[bruceb58]

That also solved my next problem which was why I only had 5 volts at the coil.

The fact that you have 11.5V at the ignition terminal with the points closed means you have a large voltage drop between the engine and your console. When you open the points, you reduce the current draw hence less voltage drop. You need to find your voltage drop. Your problem is not solved yet.

 

[Alumarine]

The fact that you have 11.5V at the ignition terminal with the points closed means you have a large voltage drop between the engine and your console. When you open the points, you reduce the current draw hence less voltage drop. You need to find your voltage drop. Your problem is not solved yet.

I have a new ignition switch that I was going to try.

 

[bruceb58]

With the ignition turned on and the points closed, measure the voltage at the input of the switch and output of the switch. If they are the same, no need to change the switch.

I gave the same advice to someone else who is having a voltage drop problem:

Get a long test lead and measure the voltage between the positive post of the battery and the positive post at your console fuse panel. Then do the same for negative to negative. You should be getting very low voltage numbers and each side should be around the same. If you don't and/or either number is more than 0.5V, you need to identify where the drop is.

 

[Scott Danforth]

between the motor and the helm there are at least two harness connectors. thats 4 connections between the +12volt source and the purple wire at the coil, not including ignition swtich, terminals, etc.

I would start by cleaning connections and measuring voltage drop like Bruce pointed out.

 

[Alumarine]

Thanks guys.
Hopefully sometime tomorrow it will stop raining for a bit so I can take a look at it.

 

[Alumarine]

Stopped raining for a bit and had a chance to get out while it was still light out.

With the ignition turned on and the points closed, measure the voltage at the input of the switch and output of the switch. If they are the same, no need to change the switch.

Points closed, key in run. BAT=11.84 IGN=11.75. I'm guessing this is close enough to being the same?

Get a long test lead and measure the voltage between the positive post of the battery and the positive post at your console fuse panel. Then do the same for negative to negative. You should be getting very low voltage numbers and each side should be around the same. If you don't and/or either number is more than 0.5V, you need to identify where the drop is.

Not sure if I understood this test.
I ran a long lead from the positive terminal on the battery to one side of the meter and checked the BAT terminal at the ignition switch which seems to be where the primary #6 red positive goes.

With the key in the off position there was no reading on the meter at the BAT terminal.
With the key in the run position on the BAT terminal I got -.40V and on the IGN terminal -.43V (that's -point 40 and -point 43).

I have not found the primary #1 black negative cable at the console yet.

I did notice that the ground to my cigarette lighter turns my entire aluminum console into a negative source.
This ground goes directly from the lighter socket to the battery.

 

[bruceb58]

That difference at the ignition switch is fine. The drop you are getting of 0.4V is on the high side. Measuring the negative is not really necessary since the ignition doesn't get the round trip drop ground. It gets it's ground back at the engine.

The problem is likely you are getting the 0.4V drop up to the ignition switch and then another drop on the way back. My next step for you is to pull apart your engine connector and make sure the contacts in there are clean.

 

[Alumarine]

Ok, the day changed from cold and rainy to just cold and drizzly.

I cleaned the contacts in the plug and receptacle with emory cloth and then sprayed with contact cleaner.
They didn't look too bad but it was full of dialectric gease.

I noticed the number 2 pin is missing one side so it looks like a D instead of an O.
I think this is for the tach signal.

Anyway now with key on BAT is .30 and IGN is .38

I haven't had a chance to remove and clean the connections under the console.
All connections on the motor end are good.

 

[bruceb58]

Also measure the voltage drop across the man over board switch as the ignition passes through it as well.

To be honest, 0.38V isn't that bad. Likely has additional drop on the trip back to the ignition ballast resistor.

 

[Alumarine]

Also measure the voltage drop across the man over board switch as the ignition passes through it as well.

To be honest, 0.38V isn't that bad. Likely has additional drop on the trip back to the ignition ballast resistor.

MOB switch has never been connected. I had my control out yesterday and noticed they weren't connected.
It's on my list of things to do.

 

[bruceb58]

MOB switch has never been connected. I had my control out yesterday and noticed they weren't connected.
It's on my list of things to do.

You talking about MOB or neutral safety switch?

 

[Alumarine]

You talking about MOB or neutral safety switch?

MOB, it's not connected, just 1 black and 1 black/yellow wire coming out of the control not going anywhere.
I'm assuming they were for the inoperative lanyard stop switch.

The 2 Yellow/red neutral start are connected and working properly.

This is a replacement for the original control according to the date stamp. Before my time.

 

[bruceb58]

OK....none of my boats have the MOB switch on the control itself so just wanted to make sure.