I purchased a mk3.5 on Monday. Over the first couple of days I had a few ‘quirks’ with the remote central locking which I presumed at the time might have been the battery in the fob.
However, when I went to drive home on Thursday, the car died shortly after starting. The alarm went off and all the hazards were flashing. I managed to get it started again and got home safely, but it felt like it was going to stall every time I had to slow down for traffic.
The car is now in the following position:
Engine Management Light is on
Central remote locking is not working at all
Stereo not powering on
Internal light is not working
Dials do a full sweep when turning on ignition (I dont think this is normal)
I have a cheap bluetooth ODB2 code reader which does not seem to get any power delivered to it (however its new and I have not tested it yet so it might not work)
As far as I can tell, all other electrics are working.
A couple of things of note…
1.) I looked at the ‘room’ fuse as this seemed the most likely problem. Sure enough it was blown. I replaced it, but this has not fixed anything.
2.) I removed the battery to fully charge it. When removing it I discovered a couple of blocks of wood under it lifting it up! After a bit of research it turned out that the battery was a Panasonic battery from a Mark 1/2! I have now replaced the battery but a brand new Yuasa HSB053. The car is starting nicely now, but I still have all the electrical problems and the EML illuminated.
Any ideas what else I can check? Are there any other fuses other than the ‘room’ fuse that might be worth checking?
I am guessing I am going to have to end up going back to the dealer, but they are not particularly local so want to check what I can myself first.
The common issue with the MK3 electrical system is water ingress through the scuttle grommits into the fusebox that sits in the passenger side of the car. Remove the panel in front of the lower door hinge to see any obvious signs of water ingress and damage.
There are a number of how tos with regards to repairing the grommits to stop further water leaks on this website and associated threads.
Sorry to hear of your problems - think this car really needs to go back to dealer for full refund. Put the old battery back in, keep the nice new one, and don’t waste any more time or money on this car. In my experience of electrical problems on modern cars ( thankfully not on my MX5) things you thought were fixed can come back to haunt you at great expense.
Plenty more MX5s out there and even MK3.5s are getting a bit cheaper at last, take your time (even get an AA Report done ) and get a good one,
Do check for damp under the glovebox and on the passenger side footwell carpet. If the scuttle grommets are leaking then all sorts of electrical problems can occur. Even if it just gives you ammunition to take to the dealer.
Refer to Post 2 from Rhino, that seems the most likely problem. Fairly common on Mk3’s. Your blue tooth code reader, is that the type that’s just a plug, and you read it via software installed on your phone? I bought one of those, but no phone, hoping it would work off my laptop which does have blue tooth connectivity. It doesn’t work. Bought a plug in code reader instead, a cheap one, but it doesn’t read ABS problems so no immediate use at all. Only other help I can offer is try a local garage with a good auto electrician at hand, they usually have code readers that will read from most cars with an OBD2 socket. But first check that fusebox outlined above, it’s important. And get some silicone sealant - Halfords or most hardware stores.
As you bought the car from presumably a roadside dealer - Not a Mazda dealer, then you may not get the satisfaction needed, my son had a hard time with door locking on his Merc A140 and the dealer never really fixed it at all, so now he has to press button lock one door at least before his fob will lock the rest. Same with the rear door - he key locks that too.
Its just so annoying because I think this is a good one. I am by no means a mechanic but I can do all the basics and the car looks solid to me except this weird quirk which just feels like a fuse or something.
The dealer is not being problematic (they are paying for the battery), so if I run out of things to check and it has to go back, hopefully it wont be too much of an issue. This is just becoming a hunt for me that I really want to resolve!
I just had another poke around and checked all the electrics for any other clues…
Working:
All lights work (although I noticed one parking light is out)
Electric windows
A/C
Power mirrors
speedo illumination
the small lights on the electric window switches
Not Working:
Stereo
Map light
Cigarette lighter/charger socket
Central remote locking
the button to open the boot
One other thing I noticed was no ‘main fuse’. According to the handbook, engine bay fuse no.18 should be a 120A MAIN fuse. This is nowhere to be seen on my fusebox (nor is there a slot to put it). I presume this is just something odd with the diagram in the handbook.
I checked all the fuses which I think might be linked and they all look fine.
I rechecked for dampness in the footwell/glovebox area (which isnt easy when you cant open the passenger door) and although there are signs of surface rust which suggests leaking in the past, there is no signs of dampness anywhere (and its been raining solid all day)
You really need to take this back to the dealer. The fact the battery has been changed from original suggezt that it may have had previous problems with starting,charging or electrics. I would suggest that something like the grommet issue has lead to a short somewhere in the wiring which could plague reliability and function of the car in the future. At the very least a significant discount of the purchase price to allow for diagnostics and repair.
If the main fuse is shot, nothing will work - that’s a clue to start with. No idea where the main fuse is on a Mk3 (or later versions) but on my car (NBFL) its buried under the main fusebox in the engine compartment.
I have to undo the two obvious top bolts to access the base, you lift off the top half, and then the two side screws which hold the fuse in position. Not something you need to know till it blows, then you have major problems!
From your list of ‘not working’ - it sounds like the ROOM fuse has blown again, which also points to an earthing fault - - check fusebox as indicated above for water ingress. - Dry it out before replacing any blown fuse, and seal it as also indicated. Borrow your partners hair dryer which will help. Silica gel also gathers damp. (Chemist - or Pharmacy as they like to be called these days!)
Frankly, till you clear this obvious step, you will get nowhere.
Tbf the dealer has been good so far and very responsive (and despite being a small dealer do informally specialise in MX5s). The car is 2010, 30k miles and 1 owner from new. I bought it with a 6month warranty and the dealer agreed to pay for the new battery outside of this warranty because it is so soon after. I dont feel like I should be eating into my warranty at this point!
Hi, the dial needles should “jump” a little when the ignition’s turned on, that’s all - a full sweep isn’t normal.
My Dad had a Ford Focus on which the dial needles suddenly started to do a full sweep on switch on, that was traced to a faulty battery.
Like other posters, I’d go with the scuttle grommet / water ingress issue - even if not leaking now, this may have damaged the electrical system via corrosion within various connectors and / or damage to electronic components caused by shorting.
Another option is to have a word with the original owner if you can locate them from the registration docs. See if the battery was changed under their ownership and if they had any problems with the car.
So with the surface rust that seems to suggest it might have had this water ingress problem in the past - I will check tomorrow when it is dry and I can see better but here is the image I managed to get today - would you agree it looks like it had has this problem in the past? If it has, how likely is it to keep getting gremlins?
Like I say, I will look again tomorrow but as I am so close to the purchase day and I have a warranty I do not want to poke about too much and try and do too much myself as it may void any warranty etc.
Yes, in my opinion the only thing that could have caused that rust is water ingress - a known issue on Mk3s resulting in all sorts of odd electrical problems & caused by cheap gaskets on the (fairly easy to replace) grommets. It’s very evident how close the corrosion is to the fusebox, indicating that there’s definitely been a water leak around this electrically critical area.
If whatever connectors / components have been damaged are then sorted & if the water ingress has been cured, then the car should be fine. It’s a good idea to replace the grommets as a precaution - I did mine at 4 years old & found they were in good order but better to be safe than sorry!
If your Obd tester is not powering up,I would check the obd socket at pin 16 for battery voltage.This is supplied from the same fuse as the “room” circuit.Also check for a good earth at pins 4/5 at the obd connector.Info here;http://pinoutguide.com/CarElectronics/car_obd2_pinout.shtml
Just an update on this for those that helped - the dealer took it back and got a full check and there was no sign of water ingress however there was a damaged cable from the fuse box to the engine and the room fuse we had replaced was actually bent due to part of the old blown fuse still being in the casing.
Cable replaced, fuse replaced, valeted and a free years warranty the car was delivered back to me so fingers crossed that’s done the job!
Just a note for the future. I had some strange electrical problems with mine, and it was tracked down to corroded pins in the cable connecting slave servers to the master server. This caused the master to think there was a problem with the equipment when the problem was with the cable…
