GT40 Retrofit Computer Power

After chasing a intermittent hot restart problem the past few months I found the fault was a EEC(computer) power relay.

While investigating this fault it came to light that PCM or Correct craft had done a retrofit to the EEC power supply wiring from the main battery box inline 50 amp fuse. (Thanks Joel M3Fan) The retrofit does away with this inline fuse and wiring altogether. Have not seen the paperwork or diagram for this retrofit but I think the method I used would be very close. Have emailed PCM and Correct Craft to check if documentation is still available for this retrofit. As yet I have not heard back but it has only been a few days.

I decided to follow this circuit right back to the 12.5 amp EEC breaker and EEC power relay. It appears in the the bilge just below the RAW water pump along with all the other wiring and control cables (in same small split black conduit as in battery box). This EEC power wiring never appears up under the dash. From under the RAW pump it goes to the rear of the engine where there is a water proof connector fitted. One side of this connector is the same red power wire on the other side of the connector it changes to a purple wire which runs into the main sheilded PCM engine loom then to the 12.5 amp EEC (computer) cct breaker.

This makes doing away with the extra EEC power wiring from the battery quite simple.

1. Cut purple wire at water proof connector.
2. Solder a round terminal connector on the wire and insulate.
3. Now connect this wire to the same terminal on the power assist solenoid as the main battery cable.
4. Remove the 50 amp fuse holder and cable at battery box.(I cut it back and left it inside the small split conduit and tucked it back through the hole where the battery cables exit) May want to use the wiring for something else in the future.

This is a nice clean install and looks factory. Without out the need to add any extra wires or joins. It now uses the heavier main battery cable as it's power source instead of much thinner gauge wire. It also removes a lot of connection points with joins that were prone to problems.

Original EEC Power cct below RAW pump (red wire exposed inside small black conduit)


Waterproof connector @ rear of engine (red on one side purple the other)


Fit round terminal to purple wire and insulate (Solder preferable)


Main battery cable(red boot pulled back). This is the terminal the purple wire will now go to.


Battery box with old 50 amp inline circuit removed.(The extra red and black leads go to amps for stereo)


Main earth cable from battery (clean this connection while your at it)

Gordon good eye it is the PP servo cable. I fitted a PP Stargazer last year. Possibly the best modification I have made especially when it is my turn behind the boat. I think you may have just given my the answer of what to do with that old power cct that is no longer required. (independent power source for the PP) I remember Joel (M3Fan) wiring a direct cct with relay for his PP will do a search for it.

On a side note also heard from Correct Craft Customer Care about the factory modification to this cct they have forwarded the question onto PCM.

Shawn, unfused the purple wire goes straight to the 12.5 circuit breaker on computer bracket which will provide the short circuit protection. You could put a extra fuse inline but it is not really needed. The original fuse was a 50amp in battery box the wire would have melted before that fuse would have blown anyway. Not sure what they were thinking with a 50 amp fuse.

baitkiller wrote: Good job however I question the automotive piece of crap battery cable connection for your main un-grounded starter supply battery terminal. The two bolt squeeze thing. You did such a nice job on the rest of it, would you please correct that? I hate those even more than wing nuts. I promise not to give you any crap about the amp wiring. Thanks,

Sure glad it is ungrounded

lewy2001 wrote: Gordon good eye it is the PP servo cable. I fitted a PP Stargazer last year. Possibly the best modification I have made especially when it is my turn behind the boat. I think you may have just given my the answer of what to do with that old power cct that is no longer required. (independent power source for the PP) I remember Joel (M3Fan) wiring a direct cct with relay for his PP will do a search for it.

I upgraded to stargazer three years ago. Some people in our club have had problems with theirs, but mine works great. Skied this morning in what would have been a +/- 20 wind with classic PP, and 16.95 every time. :-)

My old PP module was susceptible to low voltage, so I put in a relay with direct wiring to the battery. I actually used two automotive horn relays (sealed). One was switched by the ignition switch, and the other was switched by the accessory #1 switch (power port). This one was so I can change settings, etc. with the ignition and hour meter off). So excellent voltage now. Using that old lead is a great idea! You can't have too large a gage wire from the battery to PP (and PP ground). :-)

BTW, someone in our club got a zbox. He's having problems with it (in course is fine, but pre gates are very slow (under 53kph). What is really weird is that he switched back to classic mode, but the zbox still increases RPM when the skier loads just like when it is in zbox GPS mode. In classic mode, at least he gets good pre-gate speed but does get the throttle bump when he loads, but doesn't get the same time every time that GPS provides. I was thinking of upgrading to zbox, but am going to wait until I see that it works correctly.

M3Fan wrote: Stargazer is outstanding. Regarding PP supply voltage, when I rewired my PP to go direct with a relay, all I had laying around for an inline fuse was a 5A fuse. Sure enough, PP must draw less than that because the 5A continues to hold just fine.

You're right, it doesn't draw too much (don't remember what the draw is but you've certainly proven it is less than 5 amps). PP just doesn't like low voltage. I even occasionally have Stargazer PP do a continuous beep and blank screen when I'm launching (starting the engine for the first time when voltage is lower, even with direct relays to the battery). PP essentially locks up, but if I shut the engine off and immediately restart, then it is fine. Someone else in our club had the same problem a few days ago, so not unique to mine.