Zeroed mileage !

[stevemac 0]

Disconected the battery on my G60 last week. Now I have reconnected it, the mileage has zeroed itself. Reading was approx 81000 now it reads 0. Any ideas ??

[VR Zen 0]

have you tryed driving the car again , it should go back to normal again!!

[Henny 0]

Disconected the battery on my G60 last week. Now I have reconnected it, the mileage has zeroed itself. Reading was approx 81000 now it reads 0. Any ideas ??

 

Hmmm, wonder if that's why my G60 reads about 100K less than it should?!? :roll: :? :lol:

 

Does the milage now add back on when you drive it, or just stay at 0 whatever you do with the car? Sounds interesting, hope you find what did this...

[stevemac 0]

Must have been a couple of weeks ago that I had this problem - speedo now reads just over 900 miles.

 

I used to work for Mercedes and on their cars the mileage is storred in a eeprom chip inside one of the engine control units.

 

I suspect that VW will use a similar system. Eeprom chips do not need any power to retain their memory - so disconnecting the battery should not have caused any problems.

[Supercharged 2]

I would have thought they'd use an Eeprom but from what has happened suggests that there is some sort of small backup battery for the MFA and the main one has been disconected long enough to drain the small one also??? Or mabye if it is stored on an eeprom some sort of power problem has erased/reset it?

 

Have you tried the VW dealer about this, sometimes they can actually be quite helpful!!

[Kevin Bacon 5]

BMWs have external ni-cd battery packs to store service and speedo data, so VWs must have something similar? I can't think how else the speedo can hold charge when the main battery is disconnected. Worth looking into.....

 

Kev

[Supercharged 2]

Yeah, it must do - the clock always resets tho..

[ray_vr6 1]

The memory unit must be in the speedo because when I swapped the complete unit from my old VR6 (94) to my present 95 VR6(as I had alloy effect dials) - and on connecting up the mileage showed the reading from my OLD VR6. Needless to say I swapped them back!!!

[stevemac 0]

Main battery was disconnected for around 1 hour, while I was connecting my new sound installation.

 

When I bought the car, it had been garaged every winter for the last 5 years with the battery disconnected for 4 months at a time. Still held it's mileage though !!

 

Mileage must be held in some kind of eeprom chip - otherwise the cars would be too easy to clock.

 

On a Mercedes you can take the control unit off the car, leave it in a drawer for a year and it will still remember it's mileage !!!

[stevemac 0]

Anybody want to buy a VERY low mileage G60..............LOL

[Kevin Bacon 5]

An Eprom still needs a power source, unless it's a non volatile storage type, in which case power loss would not affect it. It would resume once power is restored.

 

Thinking about it, VW wouldn't bother with battery packs, so I guess the instrument pod has a fault. I would double check for a 3V lithium battery somewhere in the pod first though.

 

Kev

[LowG 0]

you maybe conected the wires somehow to discharge or reset the whole system while you were doing your system. You wont be able to change it (if you talking about the main milage read) so dont complain :D .

[Supercharged 2]

No I cant see the mileage coming back either, which is unfortunate (or not!) - Its obviously saving the figures again but does it lose tham if you disconect the battery, this should give you some idea as to if there is another small batery in the pod that needs replacing or If it keeps the current miles, I'd have to agree with LowG, In that you may have wiped the memory somehow whilst installing the system!!

[Rossco 0]

eeprom is a type of rom memory its actually a type of cache memory which is extremely non volatile and doesnt need refreshed like most other types of memory, so your problem really shouldnt be their......

unless......

the ee part of eeprom stands for electronicly eraseable so if somehow you managed to give this chip the desired voltage you may have wiped its contents, could be a possibillity i rekon, you never know wi car electrics.

 

good luck loon

 

ross

[stevemac 0]

E lectronically

E rasable

P rogrammable

R ead

O nly

M emory

 

Think you maybe right Ross. When I disconnected the battery, I removed the positive terminal before the negative - ouch!!

 

If y'all want low mileage Corrados - now you know what to do !!

[Andi 2,147,483,647]

I thought EEPROMs where wiped by ultra-violet light, not voltage mismatches.

 

I doubt very very much if disconnecting, shorting, rewiring your battery in ANY way would affect your mileage. There are capaciters, diodes, resistors and fuses all in the way in order to prevent this.

If this was so, it would be a pathetically weak design by VW, and I'm sure we would have heard of many more zero'd cars from budding ICE Installers.

 

I would guess that the EEPROM has developed a fault since the winter, and finally losing its permnament live has caused it to reset. There could be a million in one reasons...

Did you do any work near the dash with your ICE install? Splice into any looms?

 

I bet the faces of the mechanics that do your next service will be a picture when they check the mileage....

 

"Yes, the car is currently at 900miles, when do I finish running it in?" :)

[stevemac 0]

I bet the faces of the mechanics that do your next service will be a picture when they check the mileage....

 

"Yes, the car is currently at 900miles, when do I finish running it in?" :)

 

 

Nice one Andy

[G60Jet 1]

I thought EEPROMs where wiped by ultra-violet light, not voltage mismatches.

 

Correct!!! am im pritty sure you Cannot program them without the correct equipement, and in eprom chip is READ ONLY and can not be programed via a circuit. I.E. you cannot incriment it.

[sc16v 0]

Kevhaywire wrote

 

Thinking about it, VW wouldn't bother with battery packs, so I guess the instrument pod has a fault. I would double check for a 3V lithium battery somewhere in the pod first though.

 

I agree suspect there may be a break within the cluster itself.

 

Does anyone rememberwhen vw got fined by the motor Inds for clocking new cars that were being delivered to customers after PDI. :lol:

[stormseeker 0]

I thought EEPROMs where wiped by ultra-violet light, not voltage mismatches.

 

Correct!!! am im pritty sure you Cannot program them without the correct equipement, and in eprom chip is READ ONLY and can not be programed via a circuit. I.E. you cannot incriment it.

 

Wrong!

 

EPROMs (only one E) are erased by UltraViolet

 

EEPROMs are electrically erasable - like Flash memory. Usually requires a high(er) voltage (like 12V) than the 5/3.3V data levels to re-programme it. And it needs no external power source to retain its contents - take the Compact Flash Card out of your digicam, leave it in a drawer for a few months and see if you piccies of your C have disappeared :)

 

The VW spec. for the MFA digi-cluster states that it can be rolled forward once only (e.g. replacing a broken cluster) and cannot be reset. maybe that was a myth just to try and stop people clocking!

 

Maybe there's a stray 12V flying around in the back of the cluster...

[Andi 2,147,483,647]

What is an EPROM?

EPROM(Erasable Programmable Read Only Memory) can be programmed and erased enabling them to be re-used. Erasure is accomplished using an UV (Ultra Violet) light source that shines through a quartz erasing window in the EPROM package.

 

There also are OTP (One Time Programmable) EPROMs, sometimes called OTPROMs (One Time Programmable Read Only Memory), that are identical to an erasable EPROM but lack an erasing window to reduce costs. To reduce the cost these EPROMs come in a windowless plastic carrier, which is cheaper than the costly ceramic package required for the erasing window.. They can be programmed one time only, so these are used after the code is bug free.

 

What is an EEPROM?

An EEPROM (Electrically Erasable Programmable Read Only Memory) is similar to an EPROM but the erasure is accomplished using an electric field instead of an UV light source. This eliminates the need of a window. Usually, EEPROM refers to a device that requires a programmer or special voltage to program it.

 

What is a Flash EPROM?

A flash EPROM is similar to an EEPROM except that flash EPROMs are erased all at once while a regular EEROMs can erase one bye at a time. In- circuit writing and erasing is possible because no special voltages are required. To accomplish in-circuit operation, you have to write special application software routines. Flash EPROMs are also called nonvolatile memory..

 

 

So, let us assume the VW cluster contains a OTP EPROM - how can Steve reprogram his mileage back in (I assume you'd like to.. though personally I'd lose a couple of thou.. :mrgreen:) :?:

[sc16v 0]

When i fitted new dashes at the dealer, we got one chance at inputing the correct milege (you have to convert into km) using 1551.

if you put it wrong then the that was tough sh}t.

:D

[stormseeker 0]

What is a Flash EPROM?

A flash EPROM is similar to an EEPROM except that flash EPROMs are erased all at once while a regular EEROMs can erase one bye at a time. In- circuit writing and erasing is possible because no special voltages are required. To accomplish in-circuit operation, you have to write special application software routines. Flash EPROMs are also called nonvolatile memory..

 

 

So how come you can erase files (i.e. lots of bytes) from your CF (Compact Flash) card without erasing the whole thing?

 

So, let us assume the VW cluster contains a OTP EPROM - how can Steve reprogram his mileage back in (I assume you'd like to.. though personally I'd lose a couple of thou.. :mrgreen:) :?:

 

So the original, "base" mileage is stored in OTP and then you can't write to it anymore (cos it's OTP!!!) so how does the cluster retain the base+travelled mileage (or km'age!).

 

Must take mine to bits and have a poke around....

[Andi 2,147,483,647]

So how come you can erase files (i.e. lots of bytes) from your CF (Compact Flash) card without erasing the whole thing?

 

Compact Flash is not Flash EEPROM. It's a different type of non-volatile memory. Flash EEPROMs are like the BIOS in your PC, and generally about 128kbytes (depending on what it has to control). Compact Flash can now reach 2gigabytes in storage. The access methods of Flash EEPROM wouldn't be able to accomodate this capacity.

 

So the original, "base" mileage is stored in OTP and then you can't write to it anymore (cos it's OTP!!!) so how does the cluster retain the base+travelled mileage (or km'age!).

 

No idea. Maybe there's a hamster in there?? ;)

Steve - did you forget to feed the hamster?

 

Must take mine to bits and have a poke around....

 

Don't do it on a day like today with your car parked in direct sunlight. I am now sporting burns on my fingers from the temperature of the metal clips that hold the cluster in. It's a tad warm in there!! :shock:

[Andi 2,147,483,647]

This is pure guess-work.....

 

How about if the cluster contains both OTP EEPROM and a Flash EEPROM.

 

The base mileage is stored in the OTP, and the accumulated mileage is added bit-by-bit (incremental bits - simplest of computer code) to the Flash EEPROM, using 'special application software routines'.

 

The display cluster takes the value of both, adds them together, then displays it on the LCD (don't get me started on the physics of LCDs - fascinating stuff!). Due to the special programming required to alter the Flash EEPROM, the cluster is left to do the workings on this - but VW had ONE chance to alter the mileage by doing their only write to the OTP.

 

So with Steve's cluster, I would assume the Flash EEPROM has wiped itself, resulting in zero being displayed. Which would suggest the single-write to the OTP is still feasible.. and maybe the answer.

 

How you do that... pfff, I dunno!