2004 F90 Will not turn over

[lebanontn]

Thank you 99 I will be troubleshooting the loads this morning. First chance i am getting to troubleshoot. I appreciate your help!

[lebanontn]

Update. Tested battery under load no change in voltage 12.72 Volts. Went to first major junction in aft area where heavy positive and heavy negative meet 12.56 volts and check ground and no rise on voltage at that point either. Moved on to Heavy Red that meets the starter and under load volatge dropped dramatically. I removed heavy red from the started circuit and connected voltmeter to ground no change in voltage 12.56 volts. Disconnected red from trim power relay and jumped red trim wire to the heavy red that had gone to starter and tested under load and voltage dropped dramatically. Removed sky blue wire and light green wire from trim power relay and left heavy red connected to small red from power trim relay bypassing relay panel and dramatic drop in voltage under load. The small red has 3 red small wires tied to it..just so you know which one im talking about. Input please.

[99yam40]

Test as Rodbolt posted , as your description does not make sense to me.
Have no idea where you put meter leads and do not know what you mean by jumping wires.

You do not need to be disconnecting and jumping things to test, that gets confusing.

[lebanontn]

Ok here it goes. I removed starter and still had fault under load. Reinstalled starter and disconnected trim wiring total four wires and still fault under load and the funny thing is that if I tried using trim switch still showed load fault even though the four wires that run the trim light blue and light green and black and pink were all disconnected . Im about to pull key ignition switch and check it . Any thoughts?

[lebanontn]

Well I found the problem and I can say I definitely know the lay of the land. As usual its the simplest thing. The first junction at the back of the boat where the main positive and negatives arrive. The positive block was cracked and corroded as well. It checked out voltage without power and also did have a slight drop on voltage under load of about .20. I didnt think much about it but apparently that drop would have been my signal of problem there. I disconnected the positive terminal at that junction and tied the two positve wire together with bolt and nut for temporary check and making sure could not touch any part of the boat. Put battery power on again and guages worked again and load error gone as well. Headed to west marine to pick up new connector.

[rodbolt17]

sounds like the batteries are forward and terminal posts were used.
had you tested the way I described and not splatter gunned it it would have been much easier.
dont worry tough, most techs cant properly use nor interpet a volt meter.
glad you found your issue.

[lebanontn]

sounds like the batteries are forward and terminal posts were used.
had you tested the way I described and not splatter gunned it it would have been much easier.
dont worry tough, most techs cant properly use nor interpet a volt meter.
glad you found your issue.

First time is always harder then the second time and your tips helped I just totally ignored the small drop on voltage and learned from it. Will be much sharper the next time.
Thank you!!!!

[rodbolt17]

I still dont think your understang voltage drop VS current flow.
voltage is a simple matter of electrical pressure, similar to the pressure in your garden hose when the spigot is on and the nozzle is closed.
lots of pressure{voltage} no flow{current} the device doesnt work.
squeeze the trigger and pressure lowers slightly in the hose but now water{current} flows and the device works.
now kink the hose in mid point, flow is greatly reduced pressure on the supply side is way different then on the delivery side of said kink.
in a wire this is measured as a voltage drop.
when you place one meter lead on the negative post and the other on a good block ground and activate the device{starter} you are measuring the potential{pressure} differential in a piece of wire{hose} if all is well you will see less than .5 volts difference between point a and b along a section of wire.

[99yam40]

very good explanation there Rodbolt

[lebanontn]

I still dont think your understang voltage drop VS current flow.
voltage is a simple matter of electrical pressure, similar to the pressure in your garden hose when the spigot is on and the nozzle is closed.
lots of pressure{voltage} no flow{current} the device doesnt work.
squeeze the trigger and pressure lowers slightly in the hose but now water{current} flows and the device works.
now kink the hose in mid point, flow is greatly reduced pressure on the supply side is way different then on the delivery side of said kink.
in a wire this is measured as a voltage drop.
when you place one meter lead on the negative post and the other on a good block ground and activate the device{starter} you are measuring the potential{pressure} differential in a piece of wire{hose} if all is well you will see less than .5 volts difference between point a and b along a section of wire.

Cool Thank you for clarifying!

[rodbolt17]

I work with techs daily that cant understand that simple concept.
trons is trons.
doesnt matter whose label is on the hood.
thats why I like trons.
that and the US navy spent a lot of money teaching me about trons.