Possible MPEM replacement?

[Alexdecker2]

Greetings everyone! I hope you are all able to get out and hit the water lately, we have had nothing but rain and cold in the mitten and had my first day out on the water (or at least the launch) on Saturday.

So to start off the model I have is a 1996 Seadoo XP with the 787

My usual process for going to the lake is to do a pre check and fire the ski up before I even leave my driveway. I usually run it for about 5-10 seconds max, to make sure it will at least start. I did that and made my way to the lake. Got to the launch topped off my oil backed into the water and weent to fire up the ski. It turned over, fired and ran for a split second then died. I tried to fire it up again but it did not crank after pushing the start button. I did not hear the solenoid click either. I pulled out of the launch and went home

I did a little bit of diagnostics at home and have an idea of what I think is wrong but i want to see some opinions before i drop the money on this.

Checked battery voltage - 12.4v
Checked Fuses - All OK
Checked wiring making sure no connections were unhooked - All OK
Jumped starter solenoid with a screwdriver - starter cranked engine
Greetings everyone! I hope you are all able to get out and hit the water lately, we have had nothing but rain and cold in the mitten and had my first day out on the water (or at least the launch) on Saturday.

My usual process for going to the lake is to do a pre check and fire the ski up before I even leave my driveway. I usually run it for about 5-10 seconds max, to make sure it will at least start. I did that and made my way to the lake. Got to the launch topped off my oil backed into the water and went to fire up the ski. It turned over, fired and ran for a split second then died. I tried to fire it up again but it did not crank after pushing the start button. I pulled out of the launch and went home

I did a little bit of diagnostics at home and have an idea of what I think is wrong but i want to see some opinions before i drop the money on this.

Checked battery voltage - 12.4v
Checked Fuses - All OK
Checked wiring making sure no connections were unhooked - All
Jumped starter with screwdriver and it cranked the engine, starter is good.

So i looked into the wiring from the white electrical box in the front. I checked the solenoid to see if the yellow/black wire had close to battery voltage, it had 0 volts. Traced the wire back to the electrical box checking ohms from the white connector on top of the black ignition box in the back of the ski to the connector just before the white electrical box in the front I had like .4 ohms.

Went back into the white electrical box and ohm checked the yellow/red wire that goes to the starter solenoid (i think) and checked ohms along the way, all were around .4, until i got to the fuse in the electrical box (mine had a 7.5 amp in it for some odd reason, but i think it takes a 5) and there was no continuity between the fuse holder and the wiring to the starter. Fuse looked ok....

So without having a diagram (im having a difficult time finding one thats for the correct model i have) and doing just basic checked it seems as if im having an issue with my MPEM...

Does anyone think this diagnostic sounds correct? The electrical system in this seems pretty confusing to me. Is there something im missing?

Also does anyone know where i can get good diagrams for the electrical system on this ski?

 

[JeremyD615]

I know most of the published manuals don’t include the diagram for the 96XP for some reason. They are included in a supplement for this one specific year. I have one, but I’ll have to dig it up on my computer which I don’t have at the moment.

Are you getting the two beeps when you put the lanyard on the post? A bad dess post would by my first thought.

 

[Sportster-2001-951C-Stock]

I'm thinking bad lanyard post as well, or start/stop switch? Do the gauges power on with the DESS removed and pressing the start/stop button?

 

[Alexdecker2]

This ski has never beeped since ive owned it. I don't think its hooked up. As far as the start stop goes I did a continuity test when pressing the buttion and it was around 4 ohms. I also did the same thing with the DESS. There were 3 wires going to it. I don't remember whichs ones I checked off the top of my head but with the DESS hooked up I got 2 ohms.

With the start stop pressed I do get the lights to work, and when I attach the DESS it does light up as well. Gauges do not work on this ski either.

 

[JeremyD615]

Well the first thing I would do is replace that beeper. It’s hard to diagnose these issues without it working...

 

[Sportster-2001-951C-Stock]

The buzzer is probably bad, that's pretty common. Sounds like the MPEM wakes up when you apply the lanyard but without the 2 beeps we don't know if the MPEM recognizes the code as valid. I'm assuming this is DESS system, my '95 XP didn't have this "feature". If the MPEM doesn't recognize the code, it could still be the DESS post or bits of metal filings stuck inside the DESS cap will interfere with reading the code as well.

I think I'd break down and buy a beeper although as a quick check I'd see how many beeps there are by using a voltmeter or low current test light connected in place of the beeper.

 

[GGuillot]

This ski has never beeped since ive owned it. I don't think its hooked up. As far as the start stop goes I did a continuity test when pressing the buttion and it was around 4 ohms. I also did the same thing with the DESS. There were 3 wires going to it. I don't remember whichs ones I checked off the top of my head but with the DESS hooked up I got 2 ohms.

With the start stop pressed I do get the lights to work, and when I attach the DESS it does light up as well. Gauges do not work on this ski either.

Before throwing in the the towel on the MPEM I'd check and do the following: Fix or replace the beeper, you'll never be able to figure out what's going on without it. You can get into advanced diagnostics mode and so forth on the MPEM, but you need a good beeper.

I'd load test the battery, since it seemed fine then suddenly you had issues, if it's more than a few years old it may be time to replace.

Look in the SM, but with a DMM, lanyard on and off test the functionality of the DESS post, then test continuity passing through the male/female connector to the barrel connectors in the MPEM. Ohm test the lanyard, less than 10 ohms it's considered reliable, much higher the reliability drops. I have a couple old DESS caps from the 96' GSX that test close to 20 ohms, my new Atlantis lanyard tests at about 6 ohms.

Quite possible a MPEM problem, but I'd test those areas first.

 

[racerxxx]

You can do a test on the post alone removed from the ski

From waterluvr here on the forums

1. Solid black wire is a dedicated ground
2. Black wire w/yellow tracer is the return path to ground for the MPEM that supplies ground back to the DESS portion of the module
3. White wire w/grey tracer is your Maxim protocol one wire low voltage communication circuit to the module that allows the protocol to execute the function of slave / master from both the module DESS feature and 64 bit security code stored in the Dallas Semiconductor IC chip in the lanyard cap.


The DESS post is a reed switch, your lanyard contains a magnet and when placed on the post it completes the circuit between the solid black and black w/yellow trace. The presence of a ground back to the module on the Blk/Ylw allows the module to read the code stored in the lanyards ROM chip that is pre-programmed to the MPEM memory. When it recognises the security code it unlocks the ignition circuit and pulses the beeper to give you a thumbs up.

To test the post, unplug it and remove it to your bench it's easier to probe everything that way. You should have continuity from the solid black wire to the metal ring on the outside shoulder of the post all the time. You should also have continuity from the white w/grey trace wire to the small contact on the very top center of the post all the time.

With the key off the post, you should have no continuity between the black and black w/yellow wires, with the key placed on the post that should complete the circuit and show continuity between them with little to no resistance.

There are a few things you can do to test the key itself, clean it first with a q-tip dipped in alcohol and make sure the two side and one top contacts are in place and clean.

You should see continuity between both of the ground contacts in the side body of the key, and using the red test lead on either of the side ground contacts and the black test lead on the top center contact you should see less than 10 ohms of resistance on the IC serial chip.

 

[GGuillot]

To test the post, unplug it and remove it to your bench it's easier to probe everything that way. You should have continuity from the solid black wire to the metal ring on the outside shoulder of the post all the time. You should also have continuity from the white w/grey trace wire to the small contact on the very top center of the post all the time.

With the key off the post, you should have no continuity between the black and black w/yellow wires, with the key placed on the post that should complete the circuit and show continuity between them with little to no resistance.

Racer is giving specifics on testing this, which is exactly what you should do, but one step further is don't overlook the path through male/female plug under the steering, you can do a complete circuit test from the lanyard post to the barrel connections wired in MPEM.

I was getting everything checking out once until I tried this test, I'd wiggle my male/female plug connection and get a break in continuity. The symptom was randomly nothing would happen when attaching the lanyard, then at times a sudden electrical shutdown on the water. Never happen to me, but a couple times one outing with my son riding it. My problem was the male/female connector for the DESS post.

 

[Alexdecker2]

So I fumbled with the DESS post when I got home today and it cranked and started. Its also missing the beeper completely, which I think goes under the handlebar center pad. It looks like it was cut off, I have two loose wires there.

I messed around with the lanyard to see if I could duplicate the problem and I was able to get it back into the failure mode. I took the lanyard off the post and spun the post clockwise and reattached the lanyard and it fired back up again. Split the DESS connector and cleaned the terminals up and put some dielectric great in there. Terminals didn't look corroded and were making good contact.

So for now it seems solved...

Last few questions, is the DESS post something that is prone to failure on this model? I think it would be a good idea to replace it if its going bad that way It doesn't leave me stranded.

Also is there a relearn procedure that needs to be followed when replacing the post to marry it to the lanyard?

I will get a new beeper as well for diagnosing future issues

 

[mikidymac]

The post can and do fail but I wouldn't say it's really common. If yours is glitchy I would probably replace it.

The post doesn't require programming to the lanyard.