Other 70 Problem: Help

[Heldes]

Please help going away Monday and battery went flat so charged it now won't start and display saying start prevented try again but won't start

[ThomasG]

Car, year, engine?

Also- by "won't start" you mean it won't even crank, or it will crank but not start or yet something else?

[Heldes]

Sorry 54 plate 2.4 message says start prevented battery died and have charged it now this

[ThomasG]

Well.. Sorry for being rough..

But I can't help you.

I don't think there is someone who can either.

As far as I'm aware, I can't read minds, I'm pretty sure of that, I cannot remotely diagnose a fault on a blown bulb without someone checking stuff for me and answering questions.
So it will be with pretty much anybody else.

If you can't be bothered with answering question, checking this or that on your own car....

Well.. Good luck!

[Dippydog]

As ThomasG says without more detail it's all very much guesswork.Presumably there were no such problems before the battery went flat?What caused that? i.e. was the car left standing for a long period? or was something left switched on to drain the battery/etcThe battery is on the correct way round?Battery connections clean and tight?If it's an auto have you tried starting in both park and neutral positions?If it's a manual have you tried starting it with the clutch pressed?As has been asked does the engine turn over but not start?If not is there any noise[a click or a spinning noise from the starter motor?Could it be down to the immobiliser not recognizing the key[antenna ring round the ignition would be favourite here I think]?Others no doubt will know more than I do but the more detail/information you can give the better your chances of an answer.

[traebbe]

Hi Heldes,

if you install a new Battery, there's a special way to do ist on the cars.
Otherwise you get several faults.
Turn ignition on and shut down all fans/lights/seat heating/audio.
Then turn ignition off and wait for about 10 minutes to let all systems shut down.
Now remove both cables at the battery, then shorten the + and the - Wire (both not connected to the battery) for about 10 Minutes.

Connect the new battery as desribed in the following procedure:
First turn the key on position II (Ignition on)
Close all dorrs exept the luggage door.
put the + cable onto the battery and take care, that it is fixed well.
Then connect the - cable to the battery and even look, that it is fixed well.
Remove the key from the ignition-switch.
Wait for mor 10 minutes to shut down all systems.
turn the key into start position, the engine should start now.
Perhaps you had to repeat the procedure.
After running the engine switch it off, close all doors and lock/unlock the driversdoor with the Key (not the FOB) three times.
Then all systems should work correct.

[reggit]

I’ve never had an issue connecting the battery with the ignition off.
‘Start prevented’ says the transponder chip in the key cant be read.
Assuming you haven’t been fiddling with the key, the most likely suspect is the reader coil which is under the steering column shroud. Probably worth cleaning the connections on this as a starting point.

[petey]

When I was messing about with a Snap-On Verus tool, I played about with the “transmission module”. Mine’s a manual and doesn’t have one, I just wanted to see what it would do.

Turns out, bugger it up is what it will do:- if you place an invalid request on the CAN bus, this can upset modules, including the immobiliser. I had the same message and couldn’t start the car.
All I had to do was get out, shut the door and wait for the CAN bus to go to sleep (90s odd), everything resets and all is good.

During a brown out (low voltage spike) corrupt messages might well be sent on the bus causing the issue you have. I stress though, I saw it after playing silly buggers, not as a result of low voltage, but the outcome could be the same.

All you really need do is have the key in position II when you connect the battery. It won’t die if you don’t, but that’s what they ask for so you’d might as well do it. I would ALWAYS leave a door open just in case the locks have a benny attack and you don’t want to crawl through the cabin. Be aware that the battery will spark as it’s connected, just be firm with it to reduce arcing.

[Heldes]

Sorry if I'm a little vague but I am going away tomoz and just in a blind panic since this happened try to arrange lifts for the dog sitter to get here and a lift to the airport that's not gonna cost 300 quid. I suffer with high anxiety and stress levels at easy times. But thank you to the more helpful people