2004 200HP HPDI Oil Transfer Problem

[Fish Hawk]

I think I'm getting close. I found the end of the 4-wire oil harness in the engine pan. There is no blue 4-prong connector. The four wires are spliced with heat-shrink solderless connectors. It may simply be a bad connection. I will do some testing and let you know. I really appreciate your help.

[Fish Hawk]

How's this? I tested the blue wire with meter at both ends with the pump connected. At the end by the pump I get 12+ with no change when I hit the toggle switch. At the end in the engine pan I got inconsistent results. The first time I got 12+ with a drop when I hit the toggle. The second and subsequent times I got just a fraction of a volt and a small drop with the toggle.

[rodbolt17]

ok
once more.
with the key on.
from the pump blue wire to the engine block you should read 12V.
this is due to voltage avalible through the pump motor but it cant get to ground due to the open switch(s).

when you close the toggle switch you have provided a path for current through the motor to ground.

voltage is a measure of electrical pressure, once the circuit is closed pressure drops from 12V to less than .5V.

if it remains at 12V find and fix the broken circuit on the blue wire between the pump and the engine block.

yep using a voltmeter is that simple.

remember Voltage DOES NOT FLOW.
its simply a measure of pressure or electromotive force.
CURRENT flows, is measured in amperage and that's what makes things work.

[boscoe99]

From a battery did you apply 12 volts to the brown wire and a ground to the blue wire, at the point where the oil harness is spliced to the engine harness? If so, what happened?

Once it is known if the oil harness is good or not you can move on from there. Either fix the harness if needed or do a further inspection of the motor harness.

Let's say I turn on the switch to a lamp to light up a bulb. The bulb does not light up. Might be the bulb is bad. If the bulb is good it might be switch on the lamp. If the switch on the lamp is good it might be the wiring to the lamp. If the wiring to the lamp is good it might be a fuse or CB in your service panel. If the fuse or CB is good it might be wiring to your service panel.

When I say wiring I am talking about positive and ground wires. Either one being defective can cause the bulb not to light up.

Further to rodbolts comments, you need both voltage and current to make an electrical device function as designed. You can measure for voltage and see 12 volts but 12 volts alone is not enough. The device needs 12 volts plus X current. A wire may be compromised such that it will allow a voltmeter to read 12 volts at the end of the wire but it is possible that that wire won't allow the needed current flow for the device to work. But this is way too technical for most that don't perform this type of work on a frequent basis. That is why I am offering you a simpler more fool proof trouble shooting technique. It might take a bit longer but by going down the other path one can lose one's way.

[rodbolt17]

simply cannot get any more simple than what I posted.
the OP has confirmed 12V on the brown and blue wires with the key on.
this indicates that the 12V path is making it through the pump motor.
next simple test is from the blue wire to engine ground key on engine off meter set to V DC.

close the switch, meter should go from 12V to less than .5v.
if it stays above .5V go fix the broken ground path.

it simply doesn't get any simpler.

electrically, when the switch is closed a path from the blue wire connector to the block looks like a single long wire.

however if we add a resistance or open to the wire it will drop a voltage.

what we are doing is measureing the pressure difference between the pump blue wire connector and the block ground.

in a perfect world it would be 0v.

however wire has resistance as do switch contacts.
hence no more than .5V with the switch closed.

how can it get any easier?????

[boscoe99]

Methinks you are speaking in a language that is foreign to some/most.

Spanish being spoken to a Spaniard is crystal clear and simple. To me it is "huh"? Gobbledegook.

You speaking yourspeak to another technician is clear and readily understandable. To a non-technical type it is as if he is hearing you speak in Spanish when he does not know a lick of that language.

To concept of voltage drop, voltage, current, power, resistance, capacitance, impedance, etc. is mostly not understandable to the masses. Not that they are stupid, the language is just not in their vocabulary.

I believe that the more knowledgeable one is in a subject matter the more difficult it is for them to communicate as to the subject matter. We forget the time and place where it also did not make a lick of sense to us as well.

[rodbolt17]

dunno, been doing voltage drop tests to isolate bad wires and excessive resistance since I was in middle school.
course back then it was with dads old simpson 260 in the bake a lite case .

but think.
if you have a single wire in a simple two wire circuit and a light bulb in the middle.
hook up the battery (source) leads and the bub is on
ya it worked.

now place one meter lead on the + source terminal and the other on the + lamp screw.
you will(should in a perfect world) read 0V.
now move the lead to the OTHER lamp lead.
now you will read a voltage of whatever the resistor(light bulb) is dropping.

now move the meter lead to the negative source terminal and the other lead to the negative lamp lead screw, you will read 0V again.

leaving all leads in place remove the negative wire lead from the source.
you will now read source voltage.

works the same with that transfer pump.


add a resistance (or open circuit) before the lamp and it dims.
less current.

its the same for the transfer pump ground path.
its a single piece of wire as far as the electrons are concerned.

[Fish Hawk]

You guys are great. I think I follow both of you. No, Boscoe, I haven't yet applied battery voltage to the blue and brown wires at the connection in the engine pan--which sounds like a good simple test of the oil harness. There is no connector/plug in the engine pan. All four wires are spliced separately with heat-shrink solderless connectors. I will have to cut the wires, to disconnect them from the ECU, before applying voltage. I didn't want to cut the wires if I didn't have to. I've tested the blue wire with a volt meter at both ends and gotten different results at each end. Isn't that proof that the blue wire is bad?

[Fish Hawk]

Thank you both. I went ahead and cut the wires in the engine pan, connected the blue and brown wires to the battery and the pump did not run. Checked continuity; blue wire was open. After replacing the harness I examined the old one. There was a break in the blue wire near a splice in the bilge where that green corrosion had crept through the splice. Took the boat for a trial run yesterday and caught a yellowfin tuna nine miles off San Diego. Thanks!

[boscoe99]

Thank you for the feed back. Seldom received. Always appreciated.