Volvo MD2040C ignition switch

[MitchM]

are you handy with an electric 12 v dc test meter? i'd put a 12v meter on the battery -red wire to positive terminal and black ground to negative post. measure battery voltage there before you start the engine. then move up to your switch, put the red tester probe on the red hot of the switch, and the black to any ground. see what the voltage drop is at the battery switch as you turn the switch to the left to start the engine..i'd also check the voltage from the switch into the start solenoid. sometimes the wiring harness into the key start switch becomes so old cracked and degraded that your battery is putting out enough voltage, but it is not transmitting back down into t he starter solenoid. the fact that this problem is intermittent suggests that there is a loose wire somewhere that may not be allowing sufficient volts from battery up thru the switch then back down to the starter solenoid. you can also measure voltage at your 3 critical points battery , switch and solenoi after you've been out on the water for a few hours. is it possible that running instruments like your autohelm, radar, depth, lights etc etc is draining your battery below what you need to start when you're out ? checking volts at the 3 points may tell you that...i carry a portable winter battery pack $35 from pepboys, 100 ah cranking , as a backup to my engine start battery.. it's mainly been used to jumpstart friends' boats (because my engine knows i have it.) on my old boat, i couldnt run the refrigerator when out sailing or that amp draw depleted my battery so badly i couldn't start the engine .grab a copy of don casey sailboat electrical systems and a $15 digital read voltmeter, and let us know what you find.

good lck let us know what you find

[birdlives]

Hi,

I removed the nut in the picture above to inspect the ground connections. This is what I found.



I have replaced that broken terminal, cleaned the other two wires connected to the nut, sprayed them with WD40 and reconnected securely.

Since I am at the dock (ha!) the ignition switch works perfectly and the engine starts. The real test will be my return from sailing. (the TowboatUS guys are getting tired of me)

If this does not solve the problem the next step is to check the switch wires as Mitch suggested.

Don't know if this picture is clear but this is what the back of the ignition switch looks like.



It is the black round thing with the multicolored wires going to the back. I am not sure how to use the meter to test these. Do the wires just pull out and get pushed back in or is there some locking device.

Sorry for the many questions, but this stuff is new to me. I really appreciate the explanations and advice, I am learning.

Thanks,

Ron

[Hartley18]

Originally Posted by birdlives

Hi,

I removed the nut in the picture above to inspect the ground connections. This is what I found.

Well, well.. what did I tell you?!? It looks like you found your culprit.

Originally Posted by birdlives

Don't know if this picture is clear but this is what the back of the ignition switch looks like.

It is the black round thing with the multicolored wires going to the back. I am not sure how to use the meter to test these. Do the wires just pull out and get pushed back in or is there some locking device.

Yep, that's the switch, but if there's anything there that you need to test, you should be able to touch the end of each wire terminal (the grey bits) with the point of a multimeter probe - don't try to pull them out. Even better still... trust me, just leave the switch alone!!

Originally Posted by birdlives

Sorry for the many questions, but this stuff is new to me. I really appreciate the explanations and advice, I am learning.

No problems, Ron. We're all learning.

I'm just glad you've found and fixed that terminal, since it isn't something very easily found or fixed out on the water in a howling gale and without it, the engine simply won't run.

[wescarroll]

Should you need to replace your STARTER SWITCH(Diesels have no spark plugs thus no electric ignition) go to your local Tractor Supply Company(or similar tractor parts supply) and I am sure that you will find a switch exactly like the one you are replacing for about 20 dollars.

[birdlives]

Thought I would tell the end of the story. Followed most of the good advice on this thread. I did not find any other corroded or bad connections in the engine, other than the ground I sent the picture of. Gave up and had a Volvo mechanic come. He was really nice. Spent a couple of hours checking the electrical system after I had run the boat for a few hours. It did not start as usual when hot but the mechanic found nothing. He came back the next week with spare parts for the whole electrical system which he left with me to plug in one at a time and test. He had not charged me a dime. In his words "if I dont fix it I dont charge you"

Before starting what would have been a very time consuming regimen, my good buddy Mike came over and said he would fix it in an hour. He ran a new wire from the common on the keyswitch to the battery positive. Added the appropriate ground wire, and also as backup installed an emergency jumper button wired directly from the solenoid to the battery.

This worked perfectly. I can motor for two hours turn off the ignition and it now starts right up. We did not find the problem but everything works due to the redundant systems. I have not even needed to use the jumper switch.

Thanks for all the advice and help. Now back to sailing.

At last!

[Hartley18]

Thanks for the update, Ron. If it wasn't the negative, it sounds like you've got a dodgy connection somewhere in the loom.

Sometimes the best solutions are the easiest.