Hi all,
I’ve got a problem with my lovely 2007 MX-5 NC 2.0 manual, it suddenly won’t start: No crank, click but no turning — just fuel pump and circuit relay. ST relay is not clicking at this stage.
I have done some checks:
- Battery replaced.
- Starter fuse OK.
- Swapped starter relay with a known-good from the circuit relay.
- Immobiliser light turns off on dashboard.
- Interior light working.
- Jumpered clutch interlock switch to rule that out.
- Removed the starter relay and tested the socket, following instructions from another post:
Summary
I thing there is a much faster method to diagnose “no crank” I hope this helps.
Make sure the car is in neutral (manual) or park (auto) with the parking brake set, and that you stay clear of the serpentine belt or pulleys during this procedure.
First remove the fuse box cover in the engine bay.
Remove (pull) the starter relay (the one with the red arrow in the picture below)
Next have a look at the socket and the picture below with the terminals labelled A, B, C, D
- With the KEY OFF test for 12V at terminal B - confirms the starter solenoid fuse (labeled ST 20A on the fuse box cover) is OK
- With KEY OFF jump terminals A - B the starter should engage and engine crank - confirms the starter is OK
- With KEY ON test for ground at terminal C when clutch depressed or with car in park - confirms the PCM, interlock circuits, and immobilizer are OK.
- With KEY IN START POSITION test for 12V at terminal D - confirms the IG KEY 2 15A fuse (labelled as such on the cover) and the ignition switch are OK.
If the above checks out you need a new starter relay, otherwise one of the 4 steps will point you in the right direction.
- 12V at terminal B
- Ground at C with clutch pressed
- 12V at D with key in START
- However, when jumping A–B gave a spark and a click (maybe from the starter itself) but no crank.
After that, I put the ST relay back in and now it clicks when I turn the key and I can even see sparks inside it!!— but the starter still does nothing. There’s also a background noise like a mosquito, coming from the throttle body.
I haven’t hit the starter yet — Do I need to jack the car up and remove the undertray?
Wondering if that’s worth trying or if anyone has new ideas.
Thanks in advance!
A bit basic I know, but have you tried to rock the car with it in gear to “release” the starter motor as it may be sticking. The solenoid my just be stuck or stopped on a bad segment?
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Good idea, thanks, I just tried to move it within neutral gear. Maybe in gear a bit of shake of the transmission to the flywheel can unstuck the starter?
Do I also turn the key to start position to push the starter to the flywheel?
No, what you are doing is purely physical.
Does anyone know if it’s possible to get access to hammer the starter from the engine bay?
I can only find information on how to replace it, but they remove the fender plastic and a bit of frame form the floor, under the car.
It’s possible it’s the immobiliser system.
Don’t go hitting the starter, put an electrical tester on the feed and turn the key.
Flat battery. Put it on charge overnight and try again. New batteries don’t always come fully charged.
I don’t think it’s the battery. I measured 12.4V and even swapped for the one from my miata.
Either way, I’m ordering a battery charger and jump starter just in case.
Also, I tried to push the car backwards and engage gear. The speed wasn’t enough to bump start the car, but if the starter was stuck it should have been released?
The situation is the same, click from circuit and ST relays but no starter cranking the engine.
Fuses okay, and I even tried with the spare key.
Sounding like a faulty starter.
The click is the solenoid trying to push the starter pinion forward.
Only when the pinion is fully forward would power be supplied to turn the starter.
12.4V is well below fully charged. Put the voltmeter across the battery and measure the voltage when the key is turned to the start position. If it drops much below 10V, the battery is discharged.
It drops to 11.83V when trying to start.
Update: I just tried to jump start it with cables to another running car, and nothing happens.
I’m charging the battery just in case, but I think we can discard it’s a battery issue if it didn’t jump start.
Next thing I could try is to gently hammer the starter in case it’s stuck. But I think I would have to remove the front left fender liner to get access.
Interesting. 11.83V almost sounds as if very little load has been placed across the battery. Is there 12V actually at the starter motor terminal (not the solenoid) when the key is turned? If so, it probably points towards a goosed starter motor. If not, the solenoid contacts may be the problem.
So I charged the battery. Now it has 12.6V standing and it drops to 12.2V when trying to start.
I also measured the voltage at this point in the starter
I think it is the cable in between the solenoid and the starter motor.
It goes to 11.8V when turning the key to START. Still very little voltage drop, right?
Finally, I tried to hit the starter motor and solenoid but it didnt do anything.
Everything indicates that the starter died, and given the difficulty of replacing it (there’s very little room to work on it!) I will take it to a garage.
Any recommendations on a replacement part? I think better to buy new as it’s a PITA to change it, I see in eBay some listings from £90 (New Starter Motor for Mazda MX-5 Mk III NC 2005-2014 1.8 2.0 M000T37471 M0T37471 | eBay UK) to +£300 on mx5parts
And let’s see how many hours of labour they charge me…
No mention of you checking the engine earth. You mentioned having jump leads, use one jump lead (not a booster lead, they are the thin type) and connect between the battery neg and a clean area on the engine and try starting. 
You can leave the battery connected when you try this.
Another thought, any sign of water ingress in the passenger footwell? You’ve probably heard about the grommets leaking, if yours are then water can run down the wiring loom into the small fuse box in the passenger side kick panel. Have a look in there for moisture or stains, check fuse number 15 which from memory does the interior light and radio memory etc.
Some where at the back of my mind I remember one of our fellow members had water in the fuse box which shorted out some of the electrics that in turn engadged the starter motor as he drove and burnt the starter out.
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Thanks for the new ideas!
The new earth didn’t have any effect, but I checked the passenger fuse box and I could see some drops of water, and after removing a couple fuses, I can see they are wet!
Also this metal part above is rusty…
What further checks should I do?
I saw a video where they replaced a rubber seal for a little hole under the plastic under the windscreen, does anyone have the part number?
You need to dry out the fuse box (air line, hair dryer) and seal the grommet. In the downloads section as well as the forum in general there is info on how to seal the grommets. Try this link.
https://mx5oc.co.uk/download/water-ingress-nc-mk3-pdf/?wpdmdl=17938&refresh=68469835ba0351749456949
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Just seen that you’ve asked for a part number for the grommets, this link should show you them and the black caps that sometimes break.
Or you could do what many or us have done and that is just seal the ones you already have bearing in mind that if you fit new grommets and gasket, they can be little bu66ers to get out and some years down the road they will start leaking again!
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Thanks a lot for the help!
Today I removed the grommmets and the foam seal was cracked indeed!
I put them back and sealed them with a waterproof compound like this:
Regarding the starter, I’ve been watching some videos on how to diagnose the starter circuit based on voltage drops, and it shouldn’t drop more than 0.5 - 1V, otherwise indicanting that some part of the circuit has high resistance.
Either way, I can’t access the connections of the starter to properly diagnose it. I will take the car to a local garage to check and replace the starter.
