Common failures of System Interface Box (SIFB) on MSX 150 and MSX 110

[HiPeRcO]

Can we ohm test the sifb? Pin to pin
I just bought a msx110 2004 and the battery drained to 4volt in a week

The SIFB contains active electronics, so an ohm test may not be meaningful. You can bypass it with a paper clip to see if your battery drain is fixed. And you may need a new battery, 4V is an excessive discharge.

[Biglurp]

Hello. Just bought a MSX 110. Appears to have the same SIF box issue. Won't shut off with key or lanyard. Are there any replacement boxes available?, or just jump the wires? Talked to Randy, and he said to get on this forum,, lots of smart people on it. Where is the box physically located on the ski? Thanks. Gary

[ripcuda]

Welcome. The SIFB module is plugged into the wire harness below the Main relay (brown box) and ECU... above the battery.

Sadly, the original, stock SIFB modules commonly fail (not sure if it's an age thing).

There was an aftermarket option... the BT-5033 module... but it is no longer being made and I'm pretty sure Randy is long since sold-out.

Last option is the paperclip... which works fine, except you loose some functionality of the original module:

- original module detected when in reverse and told ECU... which would limit RPMs to a max of 3400. This was particularly nice when starting the ski on the trailer... as it is not uncommon for the engine to rev really high with no load on it (out of the water).

- original module detected when the engine was no longer running... and would power down the ignition/ECU systems in the event the lanyard was left in-place. This auto-shutdown feature saved draining the battery if you left lanyard key in-place.

With paperclip... you do not get any reverse 3400 max rpm protection. Nor do you get any auto-shutdown... so you MUST remove the lanyard key when you shut off the engine... or the ignition/ECU will remain powered up... and drain the battery. Otherwise... all systems normal.

Paperclip is easy. Remove SIFB module completely. Insert paperclip connecting 2 pins in the harness-side connector (see pic... note the connector locking tab for orientation - connect top left <-> 3rd down on right).

Cheers!

[Biglurp]

Thanks!