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MPEM Issue - Yellow/Red Wire to Starter Relay Always Has 12V - Transistor?

Charlie_gtx

Member
Greetings from Spain!

Hi everyone!
I'm troubleshooting my 1997 Sea-Doo GTX. It runs great, but today after the fourth or fifth start of the day, the starter motor has stuck engaged. I have checked the relay and the yellow/red wire to the starter relay from the MPEM output is constantly outputting 12V, even without the D.E.S.S. key connected.

This started spontaneously, and I suspect a faulty transistor in the MPEM. Has anyone experienced this issue? Does anyone know which transistor in the MPEM controls the yellow/red wire output to the starter relay? I know there is a xray which shows the board, but i can't see the trace from the cable to any component

Any help with diagnosing or fixing this would be greatly appreciated! Thanks!
 
While it does sound like a MPEM fault I would check the following:
Disconnect the yellow/red strip wire from the base of the start solenoid and check that the wire still has 12V on it.
If it does then inspect that wire back to the MPEM pin and check that it is not short somehow to a 12V line. There are a couple of connectors along the way and that line is right next to a 12V line. There could be corrosion between those lines at the connectors. Clean up the connectors with contact cleaner or alcohol and a tooth brush.
If those 2 things check out then it probably is the MPEM and the only surgery on the MPEM I have read about deal with diode replacement when fuses blow.
 
Thanks for the help! I disconnected the yellow/red wire from the starter solenoid, and it still shows 12.4V. I also checked the wiring and connectors for shorts or corrosion, and everything looks clean. I have 12.4v right at the first connector inside the mpem grey box.

If i dont find a solution, I'm thinking about installing a pushbutton on that line, so I can use the ski for the rest of the season and change the Mpem nect year.
 
Check if the start/stop button has failed and is constantly shorted or the wire that runs from it to the MPEM is constantly grounded.
 
No, the ground is the same as the ignition coil, the hot is an output of the mpem and is always "on".

It is not the start stop button, as it does it without the dess key.

To start it, i put the dess key, push once the start stop button and then join the yellow/red cable that i previously disconected.
 
The mpem has finally died, it doesnt recognize the key, the info doesnt turn off after 30 sec like usually, i have no spark and no beeps. Also the 12v to the starter solenoid is always on.

Now i need a new mpem and they are hard to find here.

Regards, Carlos.
 
First time posting in the forum but I've been reading these for years and there's a lot of great information here for anybody new coming on and I thank you personally.

Bypass the stator on startup if this happens, clunk clunk click click. Dreaded sounds but I had to post for you all because this bypass is quite frankly it was most incredible find for the older jet skis, and quite frankly I have a lot I've had a lot and have worked on thousands more, because I don't know how many starters and starter relays I've swapped out. When I was testing every single circuit I put tester negative to negative start stop and the positive on the positive battery and I showed continuity right across the board as well as 12 volt obviously but it was going through the engine the MPEM which essentially showed a short circuit in the mpem and technically it is but you can bypass it and make it work in your favor it's not really a bypass it's a switch out just to cut it out of the circuit for a second. I actually ran the bike for like 5 minutes without it on it's okay still and my battery charge back up to like 13.2 Disconnect the four pin plug on the alternator and you should lose continuity as well as the power supply. Yellow wire will be good when you test them out

it's the black black red telltale.

The plucking sound coming from the start stop relay engaging the solenoid or the starter are the worst. Testing out the stator I found it good. The black and black red wire was over 20 ohms. It was leaking causing my power drop

Bypassed in about 20 minutes
two switches four long wires; I did number 14 wire and soldered connections and just heat heat shrunk over them before the connection on the stator or MAG side plug, routed forward, easily accessible you can mount and you can functionally access so that after the bike starts up like a charm it'll be black and white truly and these will be mounted in the normally open position whenever you stop you should just swap them over you'll probably notice any kind of parasitic draining and your battery will always be top notch and after taking off I engage them to a closed position to start charging the battery again there is no feeling you can't even tell the difference and found it even when clicking one on at a time it didn't cause any stifle and the draw is the same as what it was before it was happening just now I can start my bike so much easier. It's like the whole way to the engine just lifted off of the battery and now all has to do is fire up the starter and throw a little spark your spark cannot go anywhere except to the CDI now it's straight to the spark plugs.

In short to recap,
cut the two yellow wires engage or disengage your alternator two switches in across the yellow wires disable the wires for the AC that comes from the alternator. Now you have no voltage drop start your bike, your starter will sound like brand new. After starting, lip switches to the closed position or on you'll start charging again. A little cumbersome with the extra switches but I didn't have to pull that damn stator out. Work like a charm runs like a dream this could save a lot of headaches.

I picked up a couple of stx's 1100 recently I think I'm just going to add the switches in the circuit just to help it start better I'll keep you posted. And thanks again for everybody else in there contributions in the prior years saved a lot of bacon.
Best regards
 
Greetings from Spain!

Hi everyone!
I'm troubleshooting my 1997 Sea-Doo GTX. It runs great, but today after the fourth or fifth start of the day, the starter motor has stuck engaged. I have checked the relay and the yellow/red wire to the starter relay from the MPEM output is constantly outputting 12V, even without the D.E.S.S. key connected.

This started spontaneously, and I suspect a faulty transistor in the MPEM. Has anyone experienced this issue? Does anyone know which transistor in the MPEM controls the yellow/red wire output to the starter relay? I know there is a xray which shows the board, but i can't see the trace from the cable to any component

Any help with diagnosing or fixing this would be greatly appreciat

the starter solenoid relay is welded together get a new one and if a metal based unit came out put a metal based unit back in
 
First time posting in the forum but I've been reading these for years and there's a lot of great information here for anybody new coming on and I thank you personally.

Bypass the stator on startup if this happens, clunk clunk click click. Dreaded sounds but I had to post for you all because this bypass is quite frankly it was most incredible find for the older jet skis, and quite frankly I have a lot I've had a lot and have worked on thousands more, because I don't know how many starters and starter relays I've swapped out. When I was testing every single circuit I put tester negative to negative start stop and the positive on the positive battery and I showed continuity right across the board as well as 12 volt obviously but it was going through the engine the MPEM which essentially showed a short circuit in the mpem and technically it is but you can bypass it and make it work in your favor it's not really a bypass it's a switch out just to cut it out of the circuit for a second. I actually ran the bike for like 5 minutes without it on it's okay still and my battery charge back up to like 13.2 Disconnect the four pin plug on the alternator and you should lose continuity as well as the power supply. Yellow wire will be good when you test them out

it's the black black red telltale.

The plucking sound coming from the start stop relay engaging the solenoid or the starter are the worst. Testing out the stator I found it good. The black and black red wire was over 20 ohms. It was leaking causing my power drop

Bypassed in about 20 minutes
two switches four long wires; I did number 14 wire and soldered connections and just heat heat shrunk over them before the connection on the stator or MAG side plug, routed forward, easily accessible you can mount and you can functionally access so that after the bike starts up like a charm it'll be black and white truly and these will be mounted in the normally open position whenever you stop you should just swap them over you'll probably notice any kind of parasitic draining and your battery will always be top notch and after taking off I engage them to a closed position to start charging the battery again there is no feeling you can't even tell the difference and found it even when clicking one on at a time it didn't cause any stifle and the draw is the same as what it was before it was happening just now I can start my bike so much easier. It's like the whole way to the engine just lifted off of the battery and now all has to do is fire up the starter and throw a little spark your spark cannot go anywhere except to the CDI now it's straight to the spark plugs.

In short to recap,
cut the two yellow wires engage or disengage your alternator two switches in across the yellow wires disable the wires for the AC that comes from the alternator. Now you have no voltage drop start your bike, your starter will sound like brand new. After starting, lip switches to the closed position or on you'll start charging again. A little cumbersome with the extra switches but I didn't have to pull that damn stator out. Work like a charm runs like a dream this could save a lot of headaches.

I picked up a couple of stx's 1100 recently I think I'm just going to add the switches in the circuit just to help it start better I'll keep you posted. And thanks again for everybody else in there contributions in the prior years saved a lot of bacon.
Best regards
I have been working on PWC for over 30 years and never, ever heard anything remotely like this.
These don't have an alternator, they have a flying magnet stator and do not work like an alternator. There isn't anything in the stator that would prevent starting ast the magnet on the flywheel isn't moving fast enough when cranking to do anything with the stator. The dreaded clunk, clunk at startup is always a bad battery, cables, or starter and rarely a locked up engine. I would advise against cutting the stator wires and adding switches but you do what works for you.
 
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