7.4GI Volvo Penta No Crank

[Ronald A]

Never mind, it won’t let me post even a single pic, said it exceeds the permissible size *. Anyways, to the 20 amp are a red to one terminal and the other has a red and an orange/pink. The 12.5 amp on the riser has red/purple on one terminal and a solid red on the other that appears to be a jumper wire from the 40 amp breaker next to it. Both the 20 amp and the 12.5 amp breakers have 12v to both terminals on them

 

[alldodge]

I'm finding a 40 amp fuse/breaker connects Red (direct from Bat) on one side, and the Red/Purple (to helm) on the other

 

[Ronald A]

I was able to upload my pics from a desktop computer - this is what I have. You can see the 20A and it's wiring in the first two pics, and the three breakers that are mounted on the riser, but the pic of their wiring isn't all that great but the best I could do. You can see that the red/purple battery wire goes to the 12.5A breaker in the middle. The other terminal of that breaker, though it's hidden in the pic, has a red wire coming off it that APPEARS to jump over to the 50A breaker next to it. There is 12V to every single terminal on every breaker pictured, and I can find no other breakers / relays / fuses. So there IS power at the breaker for the red/purple but not at the ignition switch.

 

[alldodge]

Look for a fuse or breaker under the helm. Follow the Red/purple from the key switch back toward motor.

If your unable to find a fuse, disconnect the 10 pin connector on the motor and check the pins. Even with it disconnected there should be 12V on pin 6

 

[Ronald A]

There is 12v on pin 6.

I followed the red/purple best I could buy it disappears inside the hull at spots. Where it re-emerged I follow it back and found 2 more relays, each of which have a red/purple running to each terminal 30, and both have 12v there.

I believe I also located the other circuit breakers, which were inside the box with the battery switch. The one ‘main helm’ is a 40a and has 12v to the terminal on the back. The one marked ‘acc helm’ also has 12v as does the one marked ‘mdp’. I would post pics but it still won’t allow me from my phone

 

[alldodge]

Your getting close, just keep following the voltage there will be a place before the key that it stops

 

[Ronald A]

Still working at accessing all the wiring that I can. Some runs behind the shift lever, some thru a small compartment beneath it, and some inaccessible until it
emerges from inside the hull space and into the engine compartment.

I noticed the battery power to ignition switch is red/blue not red/purple. Do you have a schematic that shows the routing of the red/blue battery power to the ignition switch? Having a hell of a time figuring out where it runs after is disappears behind the helm.

Also, the 2 red/purples that run from those relays I found way in the back of the motor eventually merge into a solid red wire which runs up to one of the 50a circuit breakers on the riser, all of which has power everywhere I check.

 

[alldodge]

Every boat manufacture is different, this is the helm wiring but it may not be much help

 

[Ronald A]

I didn’t mention this to this point because I didn’t think it relevant since the boat has been running fine since, but at this point it may be part of the issue.

A couple of weeks ago at the start of the season the 10-pin wire harness apparently rattled down and ended up in between the intake and exhaust manifold and partially melted which caused the fuel pump circuit breaker to trip as well as cooked the coil. I repaired the wires that were damaged and replaced the coil and the boat ran fine after. The first issue I’ve had was just the other day when it quit cranking in the middle of an attempt to start. I’ve double and triple checked my wiring repairs and may even consider doing them over regardless. Do you think this may have caused an issue inside the plug portion of the harness itself, or somewhere else along the line?

 

[alldodge]

Do you think this may have caused an issue inside the plug portion of the harness itself, or somewhere else along the line?

Yep, I would think that is a very good possibility

can get just one side and replace the plug

 

[Ronald A]

can get just one side and replace the plug

Sorry, lost me here - you’re saying I can/should replace just one side of the plug itself?

Also, on the 10-pin, where should I be seeing power aside from pin 6 with the key off, and then with it on?

 

[alldodge]

You can get replacement plugs
This is the Helm side

https://www.hardin-marine.com/p-132...-pigtail-mercury-plug-instrument-side-12.aspx

Can also get the motor side

Pin 6 and ground pin 1 with key OFF

Pin 5 purple when key is turned ON

 

[Ronald A]

Pin 6 and ground pin 1 with key OFF

Pin 5 purple when key is turned ON

So I should see 12v on GROUND pin?? Ugh, this is why I despise electrical gremlins, because it makes little to no sense to me most of the time, lol

And is that pin 5 in addition to 1 and 6 with key ON?

Much appreciated for the link btw

 

[alldodge]

No, ground is ground (negative), just pointed out because that is your main ground back to the neg side of the battery. Sorry to side track ya

Pin 6 is hot all the time unless the breaker blows or battery is disconnected
Pin 5 is hot only when key is turn ON
Pin 7 goes hot when key is turned to start

Keep in mind this is with both connectors connected together. Power comes from the motor side thru pin 6. Power is returned back to the motor from the key switch on pins 5 and 7

 

[Ronald A]

Ok, gotcha, thank you

 

[Ronald A]

Power at pin 6 / no power at pin 5 (purple) regardless of key position. Just to be sure it wasn’t an issue with the plug itself, I tested the purple wire coming from the engine side and before it goes into the plug harness, and no power there either

 

[alldodge]

Pin 5 only gets power if the 10 pin connector is connected. It transfers power up pin 8 to the key switch. Leaves key switch on the purple wire back to pin 5 and into the motor

So if you do not have power at (red/purple) the key when the 10 pin is connected then maybe the connector

If there is power at the red/purple on key switch, and no power at the purple wire at the key switch when turn ON, then key switch is the problem

If there is power on the purple wire at the key switch but NOT at the coil on the motor, then it can be the kill switch of wire going to from 10 pin connector , or pin 5 on the connector

 

[Ronald A]

Replaced the ignition switch just to alleviate that as a possible issue. Still no power on any terminal regardless of key position.

10 pin is connected - from engine side, power on pin 6 (red/purple) / on key side, power on thick red wire which I believe is pin 6, but no power on pin 8 (blue) or pin 5 (purple) regardless of key position.

 

[alldodge]

There is power on pin 6 with 10 pin not connected = good

10 pin reconnected

There is power on Red/purple at key switch = good

Pin 8 has no bearing - forget it

When key is turned to ON is there power to the purple wire at the key switch?

 

[Ronald A]

I just ran a jumper wire from the battery terminal on the ignition switch to the battery directly and everything works, engine cranks and fuel pumps come on