96 XP 787 electrical issues

[Waternut]

I have a 96 xp with the 787 engine that I recently purchased. I cleaned up a ton of stuff and got it running properly but there is an odd electrical gremlin that I can't seem to figure out. I don't recall this being an issue before I removed the gauges and reinstalled them but when it's in the garage, I typically leave the DESS key on the ski so it could've been like this all along and I never trigged the problem.

The DESS key works but only if it's connected before power is supplied to the MPEM. If I run the engine and then pull the key regardless of whether it's running or not, the starter button does nothing...no clicks, nothing. There is still 12v running to the MPEM and relay inside the e-box but nothing happens. If the DESS key is connected prior to connecting the battery, it'll start, stop, and restart as many times as I like providing I don't pull the DESS key.

Here's a video I took of what's going on. Of course, I managed to fumble the restart after reconnecting power but you should be able to get the idea and that hasn't happened before. Normally I reconnect the fuse or a switch and it fires right back up.

 

[artr]

So in your video you do not get 2 beeps when you attach the key to the post. The beeper is probably not working which would not be an uncommon problem on an older ski. I would try the following:
Clean up the inside of the key cap and the connections on the DESS post with a pencil eraser and then some rubbing alcohol.
If that does not fix the issue then test the Black and Black/Yellow stripe wires that run from the DESS post to the MPEM (at the MPEM box). They should read 0 ohms with the key on the post and open circuit with the key removed when tested with an ohmmeter.
If you do not get the 0 ohms with the key on the post then try placing a stronger magnet near the post or check the connections of those 2 wires to the post. If you cannot get the 0 ohm reading with those tests then the magnet switch inside the DESS post may not be working and the DESS post needs to be replaced or the magnet on the key cap has weakened where it will not close the switch in the DESS post. It would make sense to replace the DESS post first.

You should replace the beeper if it is not working because it will alarm if the ski is overheating. It gives other error conditions also. They are listed in the shop manual.

 

[etemplet]

As said above do those checks. I would add a check of the mag plug. Sometimes the wires and connectors inside the plug corrode. I've had this happen a number of times. Instead of powering up the battery, leave the battery connected and unplug and plug in the mag harness. Also, there is a ground wire at the back of the ski that connects to the battery. I've had those wires corrode internally or a bad connection. If that ground is weak the ski will not do anything. Good Luck !

You should fainly hear the battery disconnect solenoid pull in when you install the key. Check that fuse but I doubt it is bad. On my 1996 GTX I had an intermittent start problem. I worked on it off an on a number of times. I removed the rectifier in the gray box and found a wire smashed underneath the rectifier. That was my problem. Also clean all of your plugs. A bad connection is a bad connection.