Dumbass hooked up battery backwards, need help

[Seadoorider52]

98 GS 720. The battery died and the ski wouldn't crank so I pulled it out and charged over night out it back in (in the dark) and realized it was backwards. Blew the 5 amp MPEM fuse so I replaced it and hooked it back up. I am now attaching the key and getting two beeps but it won't crank at all or even engage. I hit the stop keyb5 times with the DESS key unplugged and then plugged it it and it still beeps.

Does my battery not have enough to turn the motor but still beep or did I fry my MPEM?

I feel incredibly stupid but hey crap happens I guess....I just wanna get the ski out on the water

 

[Seadoorider52]

I also read through a bunch of threads but couldn't find a straight answer. I just need to know if I need a new MPEM or not. I was under the impression of it still beeps wove like it's ready for start up that the MPEM is still good

 

[Seadoorider52]

Battery tested 100% at autozone

 

[Coastiejoe]

Well,,, The fuse is suppose to save the MPEM, but,,, doesn't always happen. I would look at every fuse you can find.

If you jump the solenoid and it cranks well, then you know the battery, cables, connections and the starter are good. Which I am certain they are.. This will just confirm it..

There is a diode in the MPEM that can pop. It can be replaced, but it is intense job..
[MENTION=41828]Minnetonka4me[/MENTION] may have some good input about the MPEM and if there is a basic test you can do.

 

[Seadoorider52]

I was told the fuse doesn't protect against reverse polarity. Is that true?

I looked in the black box next to the battery for any fuses but saw nothing. I do not know where else to look.

 

[howie099]

I bet the mpem is bad. There is only a few fuses so that's easy to check if u jump solenoid and works u can send out the mpem also to be checked.

 

[Seadoorider52]

I can get a new MPEM for like $139 and have it plug and play in 10 seconds and have it here early next week. How much is it to fix this one?


Where are there other fuses besides the MPEM?

Thank y'all for all the help

 

[Coastiejoe]

That is a bargain for an MPEM. Is it set up to accept your lanyard without reprogramming the lanyard.?

 

[Seadoorider52]

It's what I see them going for on Amazon and eBay. And no I don't believe so. I have someone that can program it for next to nothing.

Does it matter used OEM MPEM vs aftermarket new MPEM???

I typed in 98 GS 720 MPEM on Amazon and here's what I got:

https://www.amazon.com/gp/aw/d/B00M...i=AC_SX236_SY340_QL65&keywords=98+gs+720+mpem

 

[wfo speedracer]

Basucally 720 MPEM's suck, aftermarket is really no better or worse than an OEM, the aftermarket one will accept any lanyard though so no programming required

 

[Seadoorider52]

So I could just order that and be fine then? I'm gonna have a shop check everything over since it's my buddies place and it won't cost much. I'll see if he has an MPEM laying around and what it costs to have him program it. I mean it takes 10 seconds to install so I can't imagine it'd be too much. But if he confirms its the MPEM and it's more Han like $130 I should just order this new one and not have to worry about programming and throw it in myself.

 

[Dr Honda]

Just to run down my thoughts...

A) There is a 99% chance that the MPEM is bad from the reverse polarity.

B) The fuse is SUPOSED to save it. BUT... it almost never does, SINCE .....

C) The diode blows first, and sometimes allows reverse power into the rest of the MPEM.

D) If it's beeping, and you can get it to give you the error code pushing the start button 5 times... then it can be fixed by replacing the diode.

E) ALL AFTERMARKET MPEM'S SUCK !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! If they were cheap, I would roll the dice. (like $30) But since they cost as much as a good used OEM... I would recommend the OEM. I can't tell you how many of the aftermarket MPEM's be bad out of the box... or stop working after only a couple trips out.

F) As said above... jump the solenoid, and see if it cranks over. A test at an auto parts store means nothing to me. Half the time the guy doesn't know how to use the machine properly... or they just don't care. Besides... that machine is one test point, and Seadoo's generally need every bit of power that the 16BS battery can put out. So, and battery that will not start a seadoo... may be just fine in Joe-Bob's lawn tractor.

 

[Seadoorider52]

Thank you!

My buddy has a better tester at his pwc shop and potentially some OEM mpems and the ability to program them for me.

I figured the diode would go before the fuse so thank you for confirming that.

I am getting the beeps and the error code ao like you said in almost positive I fried the diode in the MPEM. How do I jump the starter solenoid and where is it located?

He is going to go trough everything with me tomorrow and hopefully I can get it out this week.

I can tell you one thing, I will double check my battery every time here on out lol