EF Fairmont.Don't know if anyone has sussed this problem yet, so I'll post problem/fix.
For the last month whenever I have filled up with fuel, after about a day(50Ks travelled) the range beeper in the trip computer has started to beep when I switch on, gauge still showing full, once it starts, gradually telling me I have less and less, untill it gets below range 20Ks,Gauge still over half full, then it has a bit of a change of mind and range fluctuates between 18 and 23 while the real fuel left runs down(gauge still showing true reading all the way).
Got the s**t with having to reset every time I turned it on,About to rip it out and disconect the beeper when I inadvertently left the ignition turned on overnight, Flat battery, after recharge, trip computer /range back to normal, worked perfect.Old battery slowed down again,trip computer lost the plot again, obvious battery on the way out ,so replaced it. No more problems.Old battery had just enough to spin motor, but so low that every time I started it, battery was so low it was like the ECU thought the battery had been disconected, needed time to reset.
Without realising it Ford has built in a battery condition indicator, If your trip/range goes out of wack, probably means winter has caught up with your battery, New battery, end of problem, Trip/ range lets you know it is not getting enough power, and screws up range estimates.

 

 

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Last edited by splatt on Sun Aug 10, 2008 8:07 am, edited 1 time in total.

Nice work.

You should always try to turn a negative into a posivive.

On my old xf if you tried to indicate with a dying battery all the lights would start coming on in a random order.

Funny things, these fords.