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  1. #1
    Vern's Avatar
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    Bad DESS post symptoms?

    Trying to help a friend out ... he has a 2005 RXP that he got more or less as a salvage. It sat with water in the hull for a few months, but ran before that. He has both yellow and white keys and when he puts them on the DESS post he gets one long beep, no gauges, no fuel pump starting. Engine turns over easily when he jumps the starter, but no spark of course. Dealers have been no help, replaced the MPEM, no difference, was thinking it might be the ECU. But, before replacing that, wanted to check DESS post ... when the DESS post fails/corrodes, are the symptoms as described above, or?


  2. #2
    Kiwi spanner handler
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    onthe front corner of the intake manifold the wiring harness can rub against the hull and then shortly after corodes through the wire and gives the symptom you have so check that, also a faulty ecu or blown fuse causes it to.
    If it powers up then the dess post is working the problem is elsewhere.

  3. #3
    Vern's Avatar
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    Thanks Jason, the ski only has 21 hours, so I think the wires should still be intact at the rub point you mentioned. If it is bad ECU, he will buy my ECU ... but we wanted to try to ensure that it really was a bad ECU rather than a bad DESS post before sending/swapping ECUs. He swapped MPEMS, no change, and I assume when he did that, he also checked fuses.

    When you say if the DESS powers up, not sure what you mean ... as of now it only gives one long beep, gauge cluster and fuel pump do NOT power up ... so I thought it might be possible that the DESS post is bad rather than the ECU. But, just not sure ... is there a way to verify/isolate whether it is a bad DESS post or bad ECU?

  4. #4
    speedskixp's Avatar
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    Vern, are you sure the ecu is programmed for those keys?

  5. #5
    Having Fun jp1300r's Avatar
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    Hooked it up to BUDs, yet? Maybe the ECU just needs to be reset. You would think the DESS post is good since you are getting a beep. I thought one long beep when you plug the key in means wrong key or doesn't reconize the key.

  6. #6
    Vern's Avatar
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    Good questions, the keys are supposed to be original to the ski, so they should be OK, but yes, maybe they need to be reset and the ECU no longer recognizes them for some reason? If you use a key not programmed for a ski, will it do the one long beep and not fire up the gauges?

    OK, so if putting a key on the DESS post always gets one long beep, then the DESS post itself should be OK?

  7. #7
    mbaseball3's Avatar
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    Re: Bad DESS post symptoms?

    not necessarily. I had a dess post go out on my 07 rxp. even proved it by bypassing the post itself. had a mickey mouse contraption but it proved it was dead. I had to fiddle with the key so much just to get anything. at times I would get the beep and felt a slight bit of hope but it wouldn't turn over. not saying for sure this is your solution to your problem since the ski has been sitting for so long, but I think its probable. using alligator clips and very short wires I hooked up the wires in a sequence that mimiced 'hot wiring' the boat. can't remember what it was exactly but there's 4 wires going to the plug. if you do decide to try this, don't destroy the post. its a 110 dollar item (or it was when I got it). I have a thread in here on this topic ill search it and hope I put in it the wire sequence to help you out.



    Sent from my HERO200 using Tapatalk

  8. #8
    Vern's Avatar
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    Thanks for the input again ... he did have it on BUDS, it found some codes, but not sure if they tried to re-program the keys. He did check all fuses too. If the MPEM was bad, and he switched to a new MPEM, would THAT require a re-program of the keys too?? I did not know where the keys 'identity' is stored ...

    I told him to have the dealer re-program the keys ... but if that does not work, and the DESS post always does one long beep, does that indicate bad ECU yet? I have not heard of ECUs failing all that often, much more common that DESS posts cause trouble.

    He did say they traced power and there is power going into the ECU, but not going out of the ECU ... is this a reliable way to verify a dead ECU?

  9. #9
    A smart admits!A wicked excuses!An idiot insists! mitsakosgt's Avatar
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    Hello Vern,
    first of all check the point of the wiring harness where it reaches the intake manifold(some rxp have this symptom because the harness came in contact with the boat and slight damage the outer of the wire).

    Then if it is ok replace(or check with an other)dess post.I have a 2004 rxp,when I get the key to dess post and I didn't get any beep or gauges move or pump,nothing at all.I change the dess post and all good.
    Third but more expensive way is to replace the ECU.

    Keys identity stored in ECU so when you change MPEM,the old keys are ready to run.

    Also do an other check with keys to an other ski if you get one beep keys are ok.

    I hope this help you,I will be glad to help you in the future if you need more help.

    Sorry for my English,they are so rusty.......

  10. #10
    Vern's Avatar
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    Good input, thank you. I noticed on my RXP yesterday that when I purposely put my key on crooked, I got the one long beep ... BUT my gauges went on, display worked, Mode button worked to cycle through the options, etc.

    Soooo, one more question ... wondering if anyone can try this test and report back? Take a key from one 4-tec ski and put it on another ski that it is NOT programmed for ... what does it do?? If anyone has two 4-tecs and could try this, it would help narrow it down even more ...

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