How to diagnose the dess post
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Best way I have come up with is...
Take the key off the post. Then hit the start button twice. Do the gauges come on?
If yes, then its the key or the post....usually the post.
If no, its a power to the MPEM, fuse, or MPEM issue.
I do have good used tested Posts in stock, PM me if I can be of help.
Take the key off the post. Then hit the start button twice. Do the gauges come on?
If yes, then its the key or the post....usually the post.
If no, its a power to the MPEM, fuse, or MPEM issue.
I do have good used tested Posts in stock, PM me if I can be of help.
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Waterluvr
New Member
I don't know about the King part, but I spent some real coin getting piles of MPEM's and key's that were relegated to being "bad" run through digital analization over the course of the last year to see just where things are going wrong in the bigger picture of the Maxim one wire protocol as it relates to deficiencies in speed over the accepted norms of the division scale.
It comes out in the wash more or less as Sea Doo having had several manufacturers of modules and ECU's and the chips found in key's aren't aging well, as the modules are aging they to have developed resistance in the internal 48K memory and 8K ROM speeds and they don't communicate well with the serial number stored in the aging chips as they are developing higher rates of resistance.
The end result is a module that can't see what it needs in the bit spacing code and won't unlock the DESS. There's a very lengthy explanation from there on how to actually bench test these things if anyone wants more info I'm happy to share what I have learned but maybe better suited to it's own thread.
To often the DESS post is blamed and in fact it's likely the strongest link in the whole one wire protocol circuit on an older machine and is by far the easiest for you guys to test at home. Just seeing the gauges power up is no indication of how the Maxim circuit is running the 64 bit encryption on the security side, the easiest and most cost effective solution in the field is to program a brand new aftermarket Atlantis key from fresh inventory they have the lowest resistance to the 5V nominal circuit you can get and will often make a module declared to be DOA work again.
To answer OP's specific question about testing the post:
1. Solid black wire is a dedicated ground
2. Black wire w/yellow tracer is the return path to ground for the MPEM that supplies ground back to the DESS portion of the module
3. White wire w/grey tracer is your Maxim protocol one wire low voltage communication circuit to the module that allows the protocol to execute the function of slave / master from both the module DESS feature and 64 bit security code stored in the Dallas Semiconductor IC chip in the lanyard cap.
The DESS post is a reed switch, your lanyard contains a magnet and when placed on the post it completes the circuit between the solid black and black w/yellow trace. The presence of a ground back to the module on the Blk/Ylw allows the module to read the code stored in the lanyards ROM chip that is pre-programmed to the MPEM memory. When it recognises the security code it unlocks the ignition circuit and pulses the beeper to give you a thumbs up.
To test the post, unplug it and remove it to your bench it's easier to probe everything that way. You should have continuity from the solid black wire to the metal ring on the outside shoulder of the post all the time. You should also have continuity from the white w/grey trace wire to the small contact on the very top center of the post all the time.
With the key off the post, you should have no continuity between the black and black w/yellow wires, with the key placed on the post that should complete the circuit and show continuity between them with little to no resistance.
There are a few things you can do to test the key itself, clean it first with a q-tip dipped in alcohol and make sure the two side and one top contacts are in place and clean.
You should see continuity between both of the ground contacts in the side body of the key, and using the red test lead on either of the side ground contacts and the black test lead on the top center contact you should see less than 10 ohms of resistance on the IC serial chip.
I find any more than 10 ohms on the IC chip usually causes intermittent or complete failure of the key to work properly with a MPEM module, my shop version of Candoo Pro will read keys up to about 20 ohms of resistance and program them to modules every time but the MPEM won't recognise them reliably in normal operation.
wfo speedracer
Active Member
I just replaced a MPEM in my GTX LTD yesterday, it would not accept the key or recognize the programmer, but if you played around with it for a while it would crank and run till you took you finger off the start button.
I swapped out the post and the lanyard, it was when I tried to program the new lanyard in and it would not recognize the programmer that I knew what was up. Just something I have never run into before and thought it worth sharing here.
I swapped out the post and the lanyard, it was when I tried to program the new lanyard in and it would not recognize the programmer that I knew what was up. Just something I have never run into before and thought it worth sharing here.
At that point check the fuses, check the rear ebox for corrosion both inside and the connector on top.
Check the plug on the mag of the motor for corrosion as on that model the ground for the front ebox comes thru that harness.
Also if you had your mpem tested and or programmed then it's possible you flip flopped the red purple wires. That's the only wire in the box you can mess up the others are impossible. Well except if you Miss the tracer on the white wire for the dess post.
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