What happened now? DESS switch problems or somethine else?

[mkeough11]

Ok, now what? Boat was starting just fine. Repaired jet pump, carbon ring and it started right up when I went to check everything. I then changed my bilge pump. I was down in the engine compartment, but was very careful. I then went to the bilge switch and when I turned it on, my electric fuel pump cycled and pressurized. Turned the switch off and back on and it pressurized again. It did it a third time. It was just like something was shorting out, or taking voltage and causing the DESS switch to recycle. It will now not give any beeps when the cap is placed on the switch. It is just like it has no power. Nothing happens. I checked all the fuses and they are all good. Even checked the one by the solenoid. Good also. Everything else works fine. All the switches, even the bilge switch works. Just not the DESS switch. Now this has happened form time to time, but not to this extent. Sometimes the battery was low and other times, it would just start working. The battery is charged and the motor turns over fine if you jump the solenoid switch, but of course will not start. Now, if I press the start button 5 times I will get 1 beep. It is like it is on a delay. It will beep 1 time each time I press it. But if I leave it alone for maybe a minute, then I have to press it 5 times to get it to beep again. And this with the DESS switch cap either on or off. How do I check the DESS switch to see if it is getting power? I have checked the connections and wiggled everything, but still no luck. I have a voltage meter and can check things, but have no idea where to start. Any thoughts about what I can check?

 

[Waterluvr]

Sea Doo leaves some circuits the MPEM controls wired hot and switches the ground side. You have to reference the wiring diagram for that MPEM before you go anywhere near it so you know what's wired hot and where so you don't let the magic smoke out of the module.

Your Dess post is a simple magnetic reed switch, the lanyard cap has enough magnetic force that it pulls the switch open prior to the locking ears seating all the way down on the ring and by completing that circuit it sends ground from the incoming black wire back to the module via the black wire with yellow tracer.

When the module get's a ground back on that BLK-YLW wire it starts the security time out function and uses the white wire with grey tracer to verify the eprom code in the lanyard chip that has been programmed to the module memory and unlocks your ignition, that happens at the point where the locking tabs on the lanyard snap down over the ground ring and the top contact in the lanyard cap touches the small contact on the top center of the DESS post.

The number one reason module's turn up dead is by people reversing the main battery cable connections or a charger / boosting source.

~Without this it's even easier to make that mistake on circuits while trying to run down a problem.

 

[mkeough11]

Well everything was fine until I turned the bilge switch and it caused the fuel pump to pressurize. Can't remember whether I had the cap on or off at that time or if I got the 2 beeps. Why would the bilge switch cause the fuel pump to come on and pressurize? Since that is the only thing out of the ordinary it seems the problem came form there. At least that is what I am guessing.

 

[Coastiejoe]

Well everything was fine until I turned the bilge switch and it caused the fuel pump to pressurize. Can't remember whether I had the cap on or off at that time or if I got the 2 beeps. Why would the bilge switch cause the fuel pump to come on and pressurize? Since that is the only thing out of the ordinary it seems the problem came form there. At least that is what I am guessing.

Something is shorted. Really can't be anything else I don't think.

You will have to start tracing wires back to see where they cross, are worn, or are damaged..

 

[mkeough11]

Ok, lets say they it shorted out somehow. It was under a tarp all winter and I hadn't touched it until then. It could have had some water in the switch. But what does that have to do with the fuel pump? Why was the switch making the pump come on? And shouldn't it have blown a fuse?

 

[Waterluvr]

Well everything was fine until I turned the bilge switch and it caused the fuel pump to pressurize. Can't remember whether I had the cap on or off at that time or if I got the 2 beeps. Why would the bilge switch cause the fuel pump to come on and pressurize? Since that is the only thing out of the ordinary it seems the problem came form there. At least that is what I am guessing.

Those circuits plug into the #4 connector to the module, the right way to approach this after you obtain the wiring diagram is to remove the connections to your battery immediately in the hopes you don't already have damage to the module, reference the diagram and specific pin locations and look for continuity in those circuits that doesn't belong there.

Your going to find one of two things, there's a short in the wiring causing this (most likely scenario) or the module is bad.

 

[Coastiejoe]

Many things could have happened. Chewed wires for one. Stored boats and skis make a great winter home for critters. And critters LOVE wire insulation...

 

[mkeough11]

"Your Dess post is a simple magnetic reed switch, the lanyard cap has enough magnetic force that it pulls the switch open prior to the locking ears seating all the way down on the ring and by completing that circuit it sends ground from the incoming black wire back to the module via the black wire with yellow tracer. "

Ok, it that is the case shouldn't I have continuity between the 2 black wires when the cap is placed on the DESS post? I have the DESS switch off and in the house and checking the circuit between the 2 black wires and I get no reading, either with cap on or off. I have continuity between the center dot on the DESS post and the white wire and I have continuity between the solid black wire and the ring, but I get nothing on the black wire with yellow tracer. I also have continuity between the 2 side contacts in the cap. With no continuity between the 2 black wires with the cap on, does this point to a bad DESS post?

 

[Waterluvr]

"Your Dess post is a simple magnetic reed switch, the lanyard cap has enough magnetic force that it pulls the switch open prior to the locking ears seating all the way down on the ring and by completing that circuit it sends ground from the incoming black wire back to the module via the black wire with yellow tracer. "

Ok, it that is the case shouldn't I have continuity between the 2 black wires when the cap is placed on the DESS post? I have the DESS switch off and in the house and checking the circuit between the 2 black wires and I get no reading, either with cap on or off. I have continuity between the center dot on the DESS post and the white wire and I have continuity between the solid black wire and the ring, but I get nothing on the black wire with yellow tracer. I also have continuity between the 2 side contacts in the cap. With no continuity between the 2 black wires with the cap on, does this point to a bad DESS post?

You are correct, with the lanyard placed on the post there should be continuity with little to no measurable resistance between the black and black w/yellow tracer wire.

Your magnet in the key is almost always more suspect initially than the post reed itself, I have a box full of bad keys with weak magnets but I rarely see a defective post switch you can test the circuit resistance of key magnets pretty easy using a good post.

Try any other dess lanyard first to see if it opens, I just grabbed my post test box I use for bench testing modules and a refrigerator magnet pulled it open right away (that magnet is 3/8 round in the back of a plastic clip) when applied to the plastic shoulder at the switch top in case your without a spare key.

 

[mkeough11]

Ok, just so I understand. The magnet completes the circuit between the 2 blk wires. When the magnet is removed the circuit is not complete. Using a refrigerator magnet (I have no spare key) I still get no continuity between the 2 blk wires.

 

[mkeough11]

OK, it is definitely the post. I took a paper clip and jumped the 2 black wires together and put the cap on and it started right up. So if that is the case, can I leave the 2 blk wires together until I can get a new post? Is that hurting anything, them staying together? The cap still has to be placed on the post to start, so can I just leave the 2 wires jumped?

 

[Waterluvr]

OK, it is definitely the post. I took a paper clip and jumped the 2 black wires together and put the cap on and it started right up. So if that is the case, can I leave the 2 blk wires together until I can get a new post? Is that hurting anything, them staying together? The cap still has to be placed on the post to start, so can I just leave the 2 wires jumped?

It's ok to send a ground back on the black and yellow tracer for testing but don't ever leave anything jumped like that Murphy shows up and voltage finds it way into that jumped circuit you won't like the cost of replacing that module.

Also, the next time you go to start it and nothing happens you'll be right back here trying to figure out why it worked initially when it was jumped but won't the next time around if left that way.

If you're anywhere near four mile bayou go stop by Gros marina and have a cold beer with Leroy and ask him to borrow a key real quick to test that.

 

[mkeough11]

Thanks Waterluvr. I just did a quick search on ebay and someone has a used DESS switch with my part # for 40.00. Glad we found the problem. If you had not told me how the DESS post worked, I would still be chasing the problem down. Soon as I get another post and have it working, I am going to break this one apart to see how it works. Just so glad it was the post and not something more. You have been a big help.

 

[Waterluvr]

Any BRP post will do to replace one of those although you may have to change the harness connector end. Ski-Doo DESS posts can be had on the cheap compared to the asking prices for Sea~Doo, the only difference is their dedicated ground wire is black with a green tracer and the return wire to the module is black with a white tracer.

I find them on Ebay to the door for $10.00 - $15.00 pretty often, on boats like yours with a factory battery disconnect switch bilge pump issues have a nasty history of shorting the ground back to the module and taking out some of the grounds in the harness and the DESS post ground is a pretty weak link in that circuit. They don't often fail, but are damaged easily enough I expect when you autopsy your's the reeds will be burned in it.

If you look at the battery switch in your boat, you'll see the power to the bilge pump circuit ties in to the front terminal lug right where the main battery power supply cable is installed, when the switch is off everything in boat is dead except for the brown and red trace wire that goes back to the pump.

People get the solid brown and brown w/red trace wrong all the time working on those and take out the DESS post and sometimes the module itself if the 7.5 amp fuse in that circuit holds out long enough.

Your three wire connector on the old pump may have had a meltdown and caused all this in the first place.

 

[mkeough11]

Not sure about the bilge pump. I have never looked at how it is connected to the battery. The bilge pump worked except for the auto function. It was all gummed up and would never come on automatically. Tried cleaning it last year to get it to work, but failed. Just now took it out and placed a new one using the same wires and it works just like it is suppose to. Put water in the bilge area and it came on automatically. The switch works fine also in manual mode. Just glad everything seems to be working now and will buy the new post on eBay tomorrow. Thanks for all the feedback.

 

[Seadoodoc]

Rookie guy here stabbing in the dark, but stereo guru. I just wired up my computerized bilge to 4 tec ignition " on " . I also wired up a float switch for auto bilge while resting. Dawned on me that when float switch activates, and or a dash switch, it would back feed power to ignition circuit and effectively wake up my tapped ignition circuit at rest. In my case I chose the " gauges" purple wire.

insertion of a 6 amp diode to prevent ignition wake up back feed solved problem. 29 cents!

just a thought

 

[Coastiejoe]

Diodes work perfectly for this kind of concern. I have used them many times on various projects.