Cant get MPEM to recognize key - One long beep

[WhiskeyD]

I'm trying to figure out an electrical issue on a 96XP that I recently picked up. The MPEM gives one long beep when you put the key on. In diagnostic mode it gives two short beeps. I tried swapping the post with a known good one but still just one long beep. Since the ski is new to me I figured maybe it was the wrong key so I took the MPEM out of my ski along with the DESS post to test with it. Still just one long beep and in diagnostic mode it gives two short beeps. I tested the main ground off the starter and all connections in the rear ebox and they seemed ok. All fuses look good as well. Weird thing is, after I reinstalled my MPEM back into my ski it is now doing the same thing. One long beep. I have a feeling its a bad connection somewhere but I cant find it. Any ideas?

 

[WhiskeyD]

Another thing to note - When I put my MPEM back into my ski I had removed the hood and all gauges from it. I didn't think you had to have the gauges hooked up in order for the MPEM to work though?

 

[AdamXP800]

No, I had no gauges hooked up on my 96. Ran fine

 

[Minnetonka4me]

yeah very few things need to be hooked up. You called me yesterday?

Try one more post. And you for sure didnt swap keys when you put the "good" mpem back in your other machine? That makes no sense.


Also...theres no reason to look of other wires IMO. if its beeping it has enough voltage to deal with the key. Your only things can be DESS post or key, or the wiring from the post to the key.

 

[Matt Braley]

Wash the post and the inside of the key with soap and water. Still you should have found it swapping like that.

Make sure the red wires coming off the MPEM have not been switched. You need the right one getting the power and the right one going to the red on the rectifier, etc.

 

[Minnetonka4me]

Yeah that can be a problem but if you hook them up wrong you would most likely get nothing.

 

[WhiskeyD]

yeah very few things need to be hooked up. You called me yesterday?

Try one more post. And you for sure didnt swap keys when you put the "good" mpem back in your other machine? That makes no sense.


Also...theres no reason to look of other wires IMO. if its beeping it has enough voltage to deal with the key. Your only things can be DESS post or key, or the wiring from the post to the key.

Wasn't me that called. I'm going to recheck everything tonight, and hit the DESS posts with a multimeter. Thanks for the help

Wash the post and the inside of the key with soap and water. Still you should have found it swapping like that.

Make sure the red wires coming off the MPEM have not been switched. You need the right one getting the power and the right one going to the red on the rectifier, etc.

I cleaned up everything pretty good last night but I will double check. The magnets on the keys love to pick up little pieces of metal in my garage. Thanks!

 

[Sportster-2001-951C-Stock]

Lanyard post white with grey stripe is the coded key chip signal to MPEM, black with yellow is on/off switch contact, black is common ground for these. You can check continuity of these three from post connector to MPEM to confirm harness is good.

I think you need to buy a shop vac though!

 

[Blademan]

I have had similar problems on my SPX and challenger from time to time.
Always ended up something to do with the battery connections .
I suggest checking all terminals, cables, clean them if you have to, and if you have a battery isolating switch, check that as well.
Sometimes its a process of elimination. Easy things first.
Good luck.

 

[1of500]

When the dess system first came out on the 95 xp 800 the keys were sensitive to cold. In fact sometimes the cold from the water in spring or fall would cause them not to start after someone came off. Wonder if you have one of those old stock keys.

 

[68ragtop]

How about putting the other ski back together, then testing the suspect post in that normally good running ski?
If that works fine, maybe you have a bad wire, or pin on the MPEM or post connector. You could check resistance of the
wires, but while its rare, I have seen wires that test ok with a meter & then fail when any load is placed on them. Good place to check though.