5.7L Volvo Penta IAC getting power when Battery turned on

[taylorrawak]

Hello, first post! Like this forum lots of knowledge, appreciate it!
5.7l volvo penta I/O
Question i just noticed my IAC makes a buzzing sound when I turn my Battery perko to either bat1 or bat 2.
Why is it getting power, do i have a stuck relay? In my opinion the engine should not get power just turning the batteries on, it should only get power when the key in the ign is turned on! is this correct?

 

[alldodge]

Howdy
Agree, it should not have power with just a battery connected.

What is your serial number?

Measure voltage at the Plus side of the coil and see if anything is measured

 

[taylorrawak]

no coil its fuel inj. 2007 model.
the engine sn is 3869366

Does the ecu control the IAC?
or do i have a relay stuck somewhere?

appreciate any ideas

 

[alldodge]

no coil its fuel inj. 2007 model.

Only way your motor does not have a coil is if its a diesel

The serial number does not show up

Does the ecu control the IAC?

Yes

I'm asking to check power at the coil because it gets power once key is turn ON. Your getting power before so I would like to know if everything is being power.

It could be there is a diode which has shorted out but need to know what motor build you have

 

[taylorrawak]

All dodge thank you, Your talking about the coil at each plug correct? I will check when I get home.
Also the fuel pump does not fire off until ign is selected with key.
Where are the diodes located, within the ECU or somewhere cheaper LOL.
Please see picture of engine and out drive ID badge.

 

[taylorrawak]

maybe the SN is the 4012211794 ???

 

[taylorrawak]

At the risk of sounding like a complete idiot where exactly on the coil do I test for power? ASSUMING I DISCONNECT WIRE 37 FROM COIL AND CHECK THERE? SEE ATTACHED

 

[taylorrawak]

ok brain fart gone took the cover off and seen the coil, to my defense the only engines i have had exposure to is ls1, 2 and 7, they have coil packs on each plug location then i know the carb engines have a coil in the ignition. so i figured this sucker would have a coil at each plug havent had the cover off until 10 min ago!
So i read the two controlling small plugs one plugged in at a time that go into the coil and they had nothing and i read the pins on both plug receptical on the coil with one of the plugs in of course
i took the IAC plug off and it had voltage of course making it actuate for a second
I then pulled the ecu fuse and turned the bat on and didn’t get the IAC humm so the ECU is getting power for sure and looks like just sending it to the IAC and nit the ign coil.
strange thing is that when i removed the plug from the iac and plugged it back in and then cycled bat it didnt do the humm until 3rd time of adding power
any ideas?
is there a relay that supplys power to the ecu for the sensors that should be closed?

 

[alldodge]

Thanks for the S/N that helps
Been out of town

The distributor in your post 7 is the wrong one for the serial number provided (its a Delco EST). Your S/N shows it has HVS distributor with the flat cap. Those caps have had lots of issues, but they would not keep the IAC turned ON

I mentioned diodes because not knowing which motor, VP used some of them inline with the field windings of the ALT. If they short out they will back feed the motor and can make it to where it will not shut OFF. Yours is not on of these

I have a 5.7 Gi wiring diagram but not the Gi-G model. The one I have shows all connections come from the ECM. So I would assume your model also has all wires come from the ECM.

Pull the ignition relay and see if it still buzzes. The ignition relay is next to the fuel pump relay, and if contacts stay together it could be powering the motor.

Can you get the motor scanned for codes?

 

[taylorrawak]

Thank your the guidance, did as you said pulled the ign relay and the iac still buzzs. what do you recommend next?

 

[taylorrawak]

no i do not have a reader, i do have obd2 of cars is there an adapter available?
only time it does not come on when bat selected to one or two is when i pull the ecm fuse. so the ecm is commanding this action?
do you have any info on the logic the ecm uses? does it go to sleep after getting bat then wake when the ign sw is turned to accy or start?
Like a set up cycle preparing for start the iac is opened?
just spit balling here!!

 

[alldodge]

The ECM powers everything, and with no power from the ignition real this is a real puzzler. There should be no power going to much and it has to have a short somewhere causing back feeding of power. It could be the alternator issue. Could disconnect the ALT and see if it stops (all wires)

Hey muc have any ideas?

 

[taylorrawak]

ok tried all wires to alt no help

 

[taylorrawak]

Keep in mind this boat only has 130 hours on it the engine is like brand new last owner never used it it’s out in the garage

 

[alldodge]

As we know something is powering the motor with key OFF. If there was not something added by the last owner, I have no idea. I would take a voltmeter and start at the motor circuits and back trace the circuits. It should not be powered

 

[alldodge]

Only other thing to think of is the ECM has an internal short, which means big bucks

 

[taylorrawak]

so maybe i disconnect all the wires in the ign key sw and test it, that way taking the keyed ign out of the circuit! could be the ign is alowing power by?
i found in my dash an incorrect sw for my anchor/nav light. the boat manufacturer put a momentary on off in sw so you have to hold the switch on to get the nav light to stay in, bone heads installed the wring sw whey built the boat maybe they wired the keyed ign wring?

 

[taylorrawak]

I have a plug shortly after the ignition switch on the dash I disconnected it turn the battery on and the vets didn’t come on do you have an email I could send a picture do you the picture I took is too large to post on this forum and I don’t know how to shrink it down I think maybe the ignition switch is not wired Correctly

 

[alldodge]

At this point I have no idea but they did do something, just don't know what

 

[taylorrawak]

ok well thank you for your help, one last question, i have looked on line for a boat engine code reader but dont need anything fancy do you have any recommendations?