[Dnick]

I am guessing you replaced the fluids the first time when no code had yet come up on your maintenance minder. It doesn't (can't) know when you actually change fluids, and if you change them early, the maintenance minder cues will never be "on schedule".
So once you've done a service before it's due (according to the maint. minder), you just have to keep track yourself of when they are next due (go by mileage, not the MM cues).
All you can do now is:
1) Clear the code & move on (go by mileage from now on).
2) Do a 2nd, "duplicate" service to get you back on schedule.
3) Clear the code & wait 'til the MM cues you again (this option will have you putting more miles on the current fluids than is recommended, but should really be OK if you really like the MM reminders & don't want to do #2).

Remember, the MM only knows how many miles since it was last CLEARED. It does not know whether or not you actually performed any service when you cleared it, or if any services were performed "early" (as in your case I suspect).

 

[Dnick]

Hey Dnick,

Thanks for the reply. I probably wasn't clear enough. The last time I did the transmission and rear diffrential fluid changes both codes WERE ON at 37,222 miles. I did not change the fluids early. My main concern now is why is the rear differential code showing up 7,000 miles later (currently at 44,000 total miles on truck) when the standard is 15,000 miles for rear differential change?

Hope that makes sense.

Yeah, that clears things up; and NO you wouldn't expect a new MM cue at 7000 miles for Rear Diff.
Maybe Joe can provide info on what the minimum should be, given the criteria/algorithm used to generate those notices?
You got anything on this Joe???