Eddie5768

@Ecomatt , @KenONeill, @PipH, @nta16, @Nogrille, @PetrolDave, @ords, M-E-R-R-Y- C-H-R-I-S-T-M-A-S all and many thanks for your contributions to my intermittent and head scratching problem. The main plug behind the carpet in the passenger footwell (the largest of the three) was removed to connect up the towbar loom three years ago. Apparently the holding clip was broken at the time and after three years it has jogged loose. The plug is now held in with hot glue so hopefully all will be well. What a saga!

Pre-Christmas family event at our house so it wasn't until this morning that I thought I would do some voltmeter tests. Discovered a design problem with the Mk 3. The driver's door and the front passenger door would not open with central locking. I could open the driver's door manually with the key, but this is not possible with the front passenger door. Trouble is the bonnet cannot be opened without opening the front passenger door! Had to abandon my testing. Sat and had a thought and decided to test the main plug. I thumped the main plug behind the carpet and everything came on and the car started. The biggest problem, knowing the cause, solved. Taking it to my local garage tomorrow for a permanent fix. HOORAY

It's working fine now @nta16

So I drove to Sainsbury's today (2miles) and it happened again. Dash lit up like a Christmas tree and then closed down completely. After shopping the car wouldn't start. Called Green Flag and waited for over an hour. When Crouch recovery arrived the car started itself without any intervention. New battery measured fine, but charging only at 12.4v. I opened the door to switch on lights, radio, blower and aircon and as soon as I opened the door charging went up to well over 13v. Charging was fine with everything switched for full load. Drove home without any problems. I'm pretty sure there must be an intermittent short to earth somewhere, maybe even in the driver's door. There I go applying logic again - I'll never learn! Finding it is going to be a nightmare unless it can be connected to diagnostics with the problem happening. Local garage will take a look next week. The new fully charged battery hasn't been on the car long enough to drain. The alternator seems OK. There must be a drain that's causing the computer to shut stuff down and refuse to allow power to the starter. Why it chooses the dash before the power steering is a mystery unless it's a fail-safe safety issue.

Heard a true story from a mechanic yesterday about a guy with an Audi who had a new battery fitted after a couple of years owning the car. He brought the car back because he thought there was something wrong with his seats which were moving weirdly. Turns out he had wrap around seats which he didn't know about and which only started working after the new battery was fitted. No logic there.

Can't find how to reply to a specific comment WhatsApp style. What am I missing?

New battery fitted by Halfords. I would normally do this, but as they recode the battery at fitting it made sense. One more thing to cross off my list of things I have always done. All now good and alternator charging fine. Thanks for your help everyone. Lots lessons learnt. @nta16I am calibrated every day by my wife 😄

It's an old multimeter, but laboratory accuracy. I would normally buy an Exide or Bosch battery, but in the end bought from Halfords (5yr guarantee). They will fit it on Monday and recode at the same time. Then I'll get the alternator checked. Even if the alternator has a fault it might well have damaged a 5yr old battery. For piece of mind I need to have confidence that the problem has gone away.

Well it seems I have been trying to solve the problem on my Mk3 Octavia with Mk1 logic! You've all been telling me that the electronics are so mind-boggling that normal rules no longer apply so I went back to basics in spite of the symptoms. I measured the voltage of the battery at below 10v and decided to replace the battery (5yrs old). After all with extra complication must come extra battery stress. Stop-Start battery available on Monday. There is still a possibility that I have a faulty alternator, but having taken two long journeys over the last 10days I still think the dash would have shown this up. Anyway one change at a time complies with the rules of problem identification, albeit a bit costly if wrong.

Brilliant video nta16. I'll be following you from now on. I feel I have a new best mate 😉.

PipH, I tried banging my head on a brick wall, but that didn't help either 😄

Thanks all for your replies. All battery terminals are fine. If the alternator is not charging properly it should have shown me on the dash (before the dash failed as I haven't run the car since). I'm trying to understand the logic of what seem like random failures as it should theoretically take me to the source of the problem, but I'm scratching my head. PipH, thank you for letting me know about the immobiliser and dash to starting relationship - very helpful. It doesn't seem to explain why the driver's door won't lock though? More info from this morning: No change at first, but after opening the bonnet (irrelevant I am sure) the dash lit up, the driver's door started to function and the car started. Not good news as it means I have an intermittent problem which is harder to find. It does however point to a dodgy connection somewhere. Had to go indoors so switched the engine off. Came back out and situation had changed. The dash lit up and the car tried to start, but there didn't seem to be enough juice and the dash lights flickered. So maybe it is the battery after all, although it doesn't quite fit the logic. Green Flag are on their way so I'll get the battery tested.

Not sure about a flat battery. Doesn’t explain the dash lighting up like a Christmas tree and then dying intermittently. Also doesn’t explain why one door out of five is not locking. All lights are working inside and out. Infotainment system is working just fine.

No - the battery light does not come on when I turn the key.

Thanks Ecomatt. I've been waiting for a mobile Automotive Electrical Engineer who I have used before, but unfortunately he's now at hospital with his dad who has COVID Pneumonia. Interested to know the connection between the driver's door central locking not working and the fact I cannot start the car. I can't think of a logical connection between the two (excuse the pun).