Freelander 1 Trip clears and voltage loss (intermittent)

[andyfreelandy]

Td4 - 2002.
Very very occasionally my TD4 refuses to respond to key, clicks and groan from starter but not turning engine over. So - am checking battery, connections, earths, battery terminals and stater switch circuit etc to try to resolve. BUT - my puzzle is this. When the battery is removed the trip mileage remains as it was. After this fault the trip mileage clears !

If the volt drop is causing it why does the trip not clear with the battery removed ? Does anyone know where the trip data is held and why this might be as it could lead me to the fault?

many thanks.............

 

[Nodge68]

Strange one that. Maybe something is causing a slight reversal of polarity under non starting, resetting the trip counter. The trip value is held in memory on the Ipack ECU. I wouldn't have thought it could be erased by anything other than the reset button, but with electronics, you never can tell.

 

[dfossil]

Well - my trip cleared itself twice on cold frosty starts recently - trickled the battery overnight and it didn't happen on the next start (the starter/engine spun over much quicker) so I have seen it happen on a sluggish start - but not noticed it happen on a battery disconnect.

 

[andyfreelandy]

Thanks - that is the point - it doesn't clear when the battery is removed ! Hence the question....Why should a seemingly low battery or high resistance connection clear it when taking the battery off doesn't. Maybe spike / reverse as Nodge says.
Have remade all starting earth connections and monitoring battery and starter with temporary voltmeters - so will be able to identify where to look next time it happens ! Last time I put a monitor on my fuel pump to see if it was the feed or the pump it never failed and hasn't failed since !

Hey ho - the characteristics of a loving freebie !

 

[Nodge68]

Electronics in cars can do strange things with voltage inconsistencies. Last year my Discovery 3 came up with "HDC Failure, Special Programmes Off" on the first start of the day. This was caused by the battery at the end of its life. Strangely it started no problem at all. However when I read the codes. There were loads of odd stuff logged. Fitted a new battery and those codes never returned.

 

[dfossil]

Hmmmm - It's amazing how your brain works like an old computer - collect facts during the day - go to bed - brain defrags - wake up - it's clear - the reason the trip does not reset on a battery disconnect - is because the ignition is not on at the time - different scenario to a violent voltage fluctuation on a cold start.

 

[Nodge68]

Hmmmm - It's amazing how your brain works like an old computer - collect facts during the day - go to bed - brain defrags - wake up - it's clear - the reason the trip does not reset on a battery disconnect - is because the ignition is not on at the time - different scenario to a violent voltage fluctuation on a cold start.

Worth the defrag then. I think you've cracked it.
I would imagine that the mileage data is stored to memory at ignition switch off, after that point it won't change until the next switch on, drive cycle begins.

 

[pscan.eu]

Presumably when you disconnect the battery the ignition is off, whilst when you are cranking it is on. Probably the instrument electronics respond to some corruption by resetting the trip memory whereas when it isn't even switched on it doesn't react in that way.