New Battery on T350 and mileage is now Zero!!!

[TvrT350t]

Had my battery changed on my T350t the other day and my mileage has now change to 000000!! Has anyone had this problem before and if so how did you resolve it?
My car is due a service very soon so i will be booking it into David Gerald in Worcester. I gather that i just inform them of this and give them a rough idea of what the mileage was before it changed to 000000

[VYT]

Yes and No

My T350 mileage went to 0 after shipping to Oz, flat battery. It is still 0. Counts up when I drive it but goes to 0 everytime I stop. I get FRAM error on startup. I guess there is a problem with the flash memory on the dash.

[macca666]

I need to change the milage on mine because I bought a second hand dash.

Have you considered talking to one of the dash boerd services companies advertised in Autotrader and other magazines ? I havnt got round to it yet but would be most interesed to find out how you get it sorted

[Biggriff]

If they are like the Tuscan one's then they have an internal battery in the dash. Sounds like yours is FUBAR'd.

[Tonto]

VYT said:

Yes and No

My T350 mileage went to 0 after shipping to Oz, flat battery. It is still 0. Counts up when I drive it but goes to 0 everytime I stop. I get FRAM error on startup. I guess there is a problem with the flash memory on the dash.

I had this problem after changing the battery.
Drivestyle HC sorted the problem out. The dash and ignition(?) ECU's had to be removed and sent to 'the woman' who resets them and re-applies the mileage.

I'm very unhappy about this, as its a ridiculous situation where a drop in power can corrupt the ECU and this is then a specialist repair and that apparently this woman is the only person who can fix the problem. This allows her to pretty much charge what she likes for probably what is no more than 10 minutes work. I was charged just short of £300 to fix this. If it happens again, I'm going to call in the OFT!

[Tonto]

TvrT350t said:

Had my battery changed on my T350t the other day and my mileage has now change to 000000!! Has anyone had this problem before and if so how did you resolve it?
My car is due a service very soon so i will be booking it into David Gerald in Worcester. I gather that i just inform them of this and give them a rough idea of what the mileage was before it changed to 000000

Re my above post. Please let us know if they can fix it without resorting to sending the ECU's away to Mrs cahsmachine. I Would like to know what they charge for this too if possible.

Edited by Tonto on Thursday 16th August 19:25

[rfisher]

Chaps.

The instrument pod ECU (driver's footwell) contains one of the ubiquetous CR2033 cell batteries to maintain the milesag EPROM.

Primative I know but there you are.

Well worth changing this every few years and certainly before disconnecting the battery.

Dunno, however, how long you get to put the new one in after taking the old one out - usually about 5 mins or so.

Also, I'd do it with the ECU still plugged in (cover off, obviously) as it most likely gets a power supply from the battery when plugged in.

All done at your own risk of course.

Fiddle away!

[macca666]

Thats all good advice for resetting milage to zero but my problem is I want to set it to what it was before I chaged the dash.

[rfisher]

My advice was aimed at preventing the mileage data being lost on disconnecting the main car battery by replacing the pod ecu coin type backup battery.

To get your mileage data back you're almost certainly going to have to send the ecu to Power or Automedon and take the hit.

Worth ringing round a few dealers though. It may be possible to 'correct' mileage via the data connector use to read engine telemetry at service time.

[hab1966]

rfisher said:

Chaps.

The instrument pod ECU (driver's footwell) contains one of the ubiquetous CR2033 cell batteries to maintain the milesag EPROM.

Primative I know but there you are.

Well worth changing this every few years and certainly before disconnecting the battery.

Dunno, however, how long you get to put the new one in after taking the old one out - usually about 5 mins or so.

Also, I'd do it with the ECU still plugged in (cover off, obviously) as it most likely gets a power supply from the battery when plugged in.

All done at your own risk of course.

Fiddle away!

I think you might mean EEPROM not EPROM?

Neither EEPROM or FRAM (or Flash for that matter) need battery backup to maintain data during power removal.

Fairclip posted a pic of the dash electronics from a Tamora which showed a coin cell in what appeared to be a Real Time Clock circuit, near a crystal. (http://www.pistonheads.co.uk/xforums/topic.asp?h=0&f=7&t=368276)

From reading these forums, FRAM errors seem to get a bit of a mention, so i must conclude that there is a block of FRAM memory in the Pod. This is where i would expect the mileage to be stored as FRAM doesnt have limited Write cycles like EEPROM. I havent inspected the electronics in detail but id be suprised if the designer used volatile memory (with a battery back up) to store the mileage. But this is TVR so i guess they might have!!

The FRAM seems to get (easily) corrupted, which is why the error gets reported, but im rather suprised that the mileage can be cleared so easily. I did a bit of work on the LCD in the Tuscans and T350 to try and find out why they fail and whether they can be fixed, as opposed to replaced. I had considered developing a new dash module using components (ie display) more suited to the environment of a TVR but was put off with issues i had over the storage/recording of milage. I had expected this to be subject to some type approval, but i guess this isnt the case given what people are reporting?

[Jappo]

Call Automedon ( http://www.automedon.co.uk ), they seem to be the authority on dash ECUs at present, currently fixing the one out of my Sag. BTW changing the battery can create another problem - the clock gets reset to 96 O'Clock - permanently.

[Lensey]

Does anyone know where I can get one of these batteries? I can only find a CR2032 ON Farnell, can these be used or does it have to be a CR2033?

I had problems with my ECU a few months back and took the battery out severall times, the only lasting problem I have is the clock won't keep time, I guess I was lucky there.

[NCE 61]

Lensey said:

Does anyone know where I can get one of these batteries? I can only find a CR2032 ON Farnell, can these be used or does it have to be a CR2033?

I had problems with my ECU a few months back and took the battery out severall times, the only lasting problem I have is the clock won't keep time, I guess I was lucky there.

The battery type in my Tuscans ECU is a CR2032.

After removing the ECU I still have the clock problem as well, appears the only fix is to send it to Blackpool.

Apparently even jump starting the car can cause this problem with the clock.

[hab1966]

Lensey said:

Does anyone know where I can get one of these batteries? I can only find a CR2032 ON Farnell, can these be used or does it have to be a CR2033?

I've not heard of a CR2033, only CR2032's. The way these part numbers work is that the 20 is the diameter of the cell in mm. The 32 refers to the height of the cell, in this case 3.2mm. If there was a 2033 it would only be 0.1mm taller thanthe CR2032, so wouldnt make any difference. They would both be 3V.

Edited by hab1966 on Friday 17th August 21:25

[rfisher]

Calm down dear - it's only a battery.

Yes I meant 2032.

Same cell that's in the plipper.

You saying that the cell battery in the pod ecu keeps the clock going?

[Pharoah]

Just to give a bit of balance - I had a flat battery in my Sagaris a few months back for a couple of weeks, changed the battery and everything is fine so either I am lucky or it doesn't cause problems every time you change / have a flat battery

[rfisher]

The hypothesis is that if you have a flat backup CR2032 on the pod ecu board and the main car battery is disconnected then the mileage data will be lost.

HTH.