I agree with others, in that the Alarm/Immobiliser System could be causing a parasitic drain. Also, all the main earth straps/cables. Braided earths in particular absorb oily deposits and dust and cause a track to earth.
When replacing these clean the contact area thoroughly to ensure a bright metal contact for the earth points.
Finally, the power drain has been traced to a faulty Body Control Module. They had to remove the dash to find that out and are probably going to have to remove a fair bit of the rest of the interior to replace the module. It’s going to cost an arm and a leg but will be worth it to be able to rely on the car again.
As a side note, the replacement battery we had fitted was a little underpowered at 45Ah/330A rather than 50Ah/370A.
Big shout out to Johnsons in Gloucester who have been really good at keeping me informed, explaining options and doing their very best to make sure I wasn’t left without transport - top notch service.
Why didn’t that cause a fault code? I recently had a live connection to the fuel pump fracture and didn’t flag a fault code. So I spent a couple of weeks working through stuff until there was only one culprit left.
Is Mazda withholding this stuff?
Maybe it wasn’t something they expected might happen, and so there was no test designed into the module to look for it.
I used to have to create software for my projects. Nightmare! I was very glad to retire!
There’s a big trade-off between how much effort one allocates to ensuring the equipment actually does its essential prime functions,
“Why isn’t it ready yet? We’d like a quick demo for customer xxxx…” Extreme management pressure.
“NO! I’ve another three weeks in the plan before that milestone! Maybe you’d like someone else to take it over?” Worm turns the screw on management…
and then eating into limited hardware resources and the dreaded deadline time to design “nice to have” (but pointless) box ticks and extra diagnostics for running down once in a lifetime white-rabbit holes…
I’m impressed by the high quality of engineering design in all the Mazda stuff I’ve examined.
For whatever reason the fuel pump wasn’t working, I think there should be a code to say either it’s not working or because it’s not working there is no fuel pressure. I know nothing , but that seems to me a fairly basic function of any diagnostic system?
If I had followed my instincts and followed up the fact that there was no strong smell of petrol with the plugs out and the engine turning over, I wouldn’t have gone down the rabbit hole of replacing cam and crank sensors etc.
I’ll not make that mistake again until the next time…
Absolutely.
This is why Mazda have symptom based diagnosis procedures for when there are no fault codes. For a non-start the first few steps will be, does it crank, Is there compression, is there fuel pressure, is there a spark.
Ooh, sorry, Richard that raises a hackle. I agree that there is a lot of fine engineering (have you looked at their technical magazines?) but I think they missed the “design for maintenance” courses. In working on the suspension, there were so many issues over accessibility, dissimilar metal corrosion, forced replacement of expensive components, etc. not to mention the rust trap in the sills near the rear wheel. When I worked a Mistsubishi in Nagoya back in the 90’s, I was told that Japanese cars were designed for a three year life because the “MoT” rules made it cheaper to buy a new car than make all the mandatory replacements. They were all bought up cheaply and sold abroad, that is Africa and India.
I tend to agree.
I still think the engineering design is generally excellent.
BUT the next stage begins where it is put into production, and then the marketing and accounting departments take over and push the product down the quickest, cheapest, box-tick route possible, inventing cost-cutting compromises and short cuts.
This is one of the curses of modern mass production and international business.
Oh well.