hi-line fault

[Rob.W]

Hi i am new to the forum and just brought my first mg ZT-T i have had it about 6 months now and loving every moment.

I have run into a problem with the sat nav cd unit, its not turning off and draining the battery but works fine otherwise.

Looked through the forum for answers and yep water has got in, i am looking into this and sealing the vents and there is what looks like a drain tube guessing its from the sunroof just floating around any ideas.

The thing is do i have to buy a new unit or can it be bypassed i.e give it a switched feed! or will this do more damage then good.

also is it right that the unit needs two minutes or so to shut down if so can i put a delay switch in to do this, so after say two and a half minutes the power is cut.

thanks rob

[HarryM1BYT]

Putting a switch or a delay in the feed will not really help, it is supposed to be allowed to switch itself off. If the red LED is staying on, it hasn't shut itself down.

For the red LED to be able to go out, the car has to be left untouched for around 2 minutes - no door opened or closed, but obviously the boot left open so you can see the LED.

Purple/pink is the 12v live all the time feed. Purple/yellow is the switched feed (AKA remote).

If you have wet around the satnav (offside boot wall), no doubt your wheel well will have water in it too - which will swampt the radio and TV modules in there. Those are even more likely to discharge the battery.

[Rob.W]

Thanks for the reply the unit does not shut down its a tourer so i ca see through the window it flickers but stays on.

yes the wheel well did have water in as well but i have removed the cd unit and the battery drain has stopped!

are the units linked so once the cd unit removed there is no power to the ones in the wheel well or can i say it is the the cd unit draining, i am asking so i don't replace the wrong unit if needed.

i was looking at the cut off idea as this will cost about £ 30.00 to do where new unit/units would be hundreds.

if i bypass will it cause any more problems i.e software in the unit i am guessing if it is the cd unit at fault and i give it a try, worst case i will have to buy a new unit.

has anybody else tried this or any more info on this problem would be of great help

thanks rob

[Ragman]

Have you dried the sat nav unit out - take it out, stick it in the airing cupboard - helped mine when it started messing me about

[Reebs]

Originally Posted by Rob.W

....are the units linked so once the cd unit removed there is no power to the ones in the wheel well or can i say it is the the cd unit draining, i am asking so i don't replace the wrong unit if needed.

thanks rob

The nav computer is linked to the radio tuner and video module in the spare wheel well via the Kbus, if the nav computer doesn't shutdown, then the video module continues to wait for the signal to switch off, which it never gets, hence you will hear the fan continue to run in the video module below.

However, having said they are linked, you can remove the nav computer and still have full use of the radio and front screen, though the display will be much cruder with large blocky text, and, of course, no Sat Nav option listed.

Best advice after drying out the nav computer as Ragman suggests, is to see if the video module goes to sleep after 1 min or so of no activity in the car whitout the nav computer having been refitted.

Replacement nav computers do come up on ebay from time to time for anywhere between £50 - £200, but as the non shutdown issue is the reason for many units being sold as spares, it's a bit of a game of russian roulette as to what you end up with.

[Rob.W]

Many thanks for the replies ,best to start with the basics i guess

but with the nav unit out i get no screen, radio and cd work but screen blank does this point to other units faulty

As i have the trims off drying the back out and sealing the vents i will remove all units and try drying them out for a day or two and give it a go fingers crossed.

just would like to say what a great forum you have here and looking forward to many years with the ZT-T, seen a few issues to look out for so far looks like i will be busy for the next few weekends checking the car over but what a joy to drive.

thanks again rob

[Reebs]

With the sat nav computer disconnected, the video module (box on the left of the boot well) should kick in with it's own back up menu screen which looks more like an old ZX Spectrum computer display. I have driven my car without the nav computer connected, and always had a screen display.

Did you say that the nav computer LED did blink after a couple of mins of inactivity, but just not go out?

Maybe it's the video module which is at fault then and again it is keeping the Kbus awake hence the nav computer not switching off also

The only way to really check is to do a bit of substitution. I have a spare video module you can try, but I guess Brighton to Southampton might be a little far to check.

[Rob.W]

Thanks for the help

It seems it can't make its mind up some times it blinks and stays on then makes a noise i.e cd running blinks and keeps repeating this, but a couple times it turns off but restarts after say 10 seconds

i will pull out the units and allow to dry but the rain has put a stop to me getting out there, had a quick look and car is dry and with all this rain!!

Had a look through the service history today and found an invoice for a new tv module replaced because of a battery drain fault so maybe its this is at fault again there was about a large cup full off water max in the well so could of got wet!

Thanks for the offer Reebs i work down your way now and again its only 2 hours max in the van so about an hour in the zt but seriously it could be an option thank you, i will take a good look when the sun makes an appearance (about mid June then)

thanks rob

[HarryM1BYT]

Originally Posted by Rob.W

Thanks for the reply the unit does not shut down its a tourer so i ca see through the window it flickers but stays on.

yes the wheel well did have water in as well but i have removed the cd unit and the battery drain has stopped!

are the units linked so once the cd unit removed there is no power to the ones in the wheel well or can i say it is the the cd unit draining, i am asking so i don't replace the wrong unit if needed.

i was looking at the cut off idea as this will cost about £ 30.00 to do where new unit/units would be hundreds.

if i bypass will it cause any more problems i.e software in the unit i am guessing if it is the cd unit at fault and i give it a try, worst case i will have to buy a new unit.

has anybody else tried this or any more info on this problem would be of great help

thanks rob

They are all powered individually, but from the same feeds. Basically the purple/yellow should drop down to 0v when the ignition is turned off, which signals the various things to shut themselves down. Why not check if that wire does what it is supposed to, as a first step? The purple/pink should remain at +12v all of the time, to allow things to shut themselves down gracefully. You can unplug any item in the boot and the remaining items should work as usual, so far as power is concerned.

To check which item(s) still draw power when off, you could perhaps try pulling fuse 33 and bridging across where it goes with a meter set on the amps range. I never tried doing it, but would suggest everything when shut down properly should draw less than 1mA. Just the LED staying on will draw 5 to 10mA. Unpluging things in the boot one at a time, should help identify which ones are still drawing current.

[HarryM1BYT]

Originally Posted by Rob.W

Had a look through the service history today and found an invoice for a new tv module replaced because of a battery drain fault so maybe its this is at fault again there was about a large cup full off water max in the well so could of got wet!

Even half a cup can percolate around in the closed space causing lots of condensation on the PCB's in the boot - it needs to be dried out thoroughly and kept dry. Check the tail light lens seals, the vents in each side and the trim strip fixings. Maybe they replaced the TV hoping it had fixed the problem and the original problem has come back.