DESS and mpem

[mpyrol]

I'm pretty sure I have a faulty MPEM in my 97GTX ski. The ski goes completely dead and get no signs of life as if the battery is gone. I am pretty far along with diagnosis and this what I think I know. Key post check ed good including key magnetic relay. It switches at the mpem. Start switch at mpem verified. Beeper verified. Power on both sides of the fuses confirmed. Continuity checked on grounds from front to back of ski. The ski works perfectly when it works. My thought is either the key is bad or the mpem. Even if the key is bad shouldn't I be able to get beeps or gauges with the start button? I read a post that has instruction on checking the load on the key and it should be 10 to 20 ohms. I have no load. Any advice would be appreciated.

 

[artr]

You said there are still times when the ski works perfectly. During those times if you just press the start button (no key) the gauges should wake up for about 30 seconds (no beep). Then attaching the key should give 2 short beeps and the engine will crank and start with the start button. If you get all those responses (including beeps) it would be less likely the MPEM is faulty but may be just losing its power or ground connection intermittently.
I would start by checking the condition of the battery by having it fully charged and load tested. I would then check the black wire coming from the MPEM and its connection to engine ground by removing it and inspecting both end of the wires and connectors are clean and corrosion free. Also put and ohmeter on the wire while disconnected and move the wire around to test for internal breaks/corrosion (resistance should be zero and not change). I would do the same test with all of the following wires: large black cable that runs from the battery to the starter, large red cable the runs from the battery to the start solenoid, the red/purple wire running from the start solenoid to the MPEM (several sections with connectors).

 

[mpyrol]

Thanks for the response. I went back and checked all the connections and charged the battery, still no response. The way I understand how this ski works I should be able to activate the timer with 5 presses of the start button without safety lanyard. Is this correct? If so I have a bad mpem and won't worry with a key.

Thanks
Brian

 

[artr]

Pressing the start key just once without the safety lanyard should wake up the gauges for the duration of the 30 second timer (no beep). Pressing the start key 5 times (without the safety lanyard installed) activates an advanced self-diagnostic mode and you should hear one short beep and one long beep that confirms this mode is activated. Then placing the safety lanyard on the switch and pressing the start key should start the ski if there are no issues. Section 07-06 of the 97 service/shop manual gives other error beep codes that you would hear after putting on the safety lanyard when in the advanced self-diagnostic mode if problems were detected.

Does your ski actually start and run sometimes or is it completely dead?

I believe I read in the forum where Westside Powersports can test an MPEM as a service. I think I also read where the replacement MPEMs they have can be expensive.

 

[mpyrol]

Thanks for your confirmation. It will not do anything right now. The last couple of times it sat and "woke up". I'm checking all the voltages at the connectors in the mpem box. Unless there is something that drives this into complete shutdown. Does anyone know if the purple wire is a DC or signal output?

Brian

 

[artr]

If the purple wire is the same as my 96, then it provides 12V to the gauges by daisy-chaining through them along with a black wire ground.

 

[mpyrol]

I purchased an aftermarket speeduino unit. I'll have to add some sensors and igniters. There are a lot of advantages and hurdles but at least I have an alternative. It'll match my Arduino info-center format. I'll post all that if there is any interest.