NB 1.6 2000 Steering Lock:- electrical device attached; what is it?

Attached to the front of the steering lock on the column is a small cube shaped electrical device, with two wires connected to it. They run back to a small four wire connector mounted on top of the ignition switch. Both black, I think. The other two wires - green - go to the key detector switch next to it on the lock. What is this device? Is it part of the Cobra immobiliser?
Might it have caused the heating of my steering lock on a recent ninety mile trip? Key and barrel end of lock too hot to touch for more than a couple of seconds. Not noticed this on short local driving.
I can disconnect it, and the car still starts and runs. Is that safe, to find out if that is the culprit? I think it’s attached to the lock body by a screw, but its tricky to see. Any ideas to satisfy my curiosity? Also, ideas on a hot steering lock? The ignition switch itself shows no sign of overheating at the connectors. Thank you.

Is this a UK or Japan spec NB 1.6?

Ooh, straight in with the hard ones, eh? Answer; I haven’t a clue. How do I tell? I understand it was an import, but my ignorant response to that is, ā€˜aren’t they all?’ First registered here in 2003. Manufactured 2000. And DVLA, I’ve just checked, call it a Eunos Roadster, so Japan spec, then. A/C and electric windows. Is that right?

Got a photo of this thing?

I’ll work on that, difficult to get a good angle, and my phone is not ā€˜smart,’ so I’ll get someone else to do that for me.
Saz9961, I’ve just realised it was you sold me that seat recliner mechanism last year. Works fine.

As its a grey import, the device is probably part of an aftermarket immobilizer.

NB imports differ from UK versions by seats (fixed headrest buckets), rear bumper reflector (red, not amber), badging on rear (Roadster not MX5. BTW, its a Mazda Roadster, not Eunos Roadster)

If you’re being pedantic, then shouldn’t it be ā€œRoadster not MX-5ā€?!

I now have a few photos, and will put them on here if and when I work out how to do so!





Are these photos here?

Previous post shows the device I think is making the steering lock and key hot. It appears to be a coil or motor. The screw holding it is one of a pair, across the diagonal, and I’ve loosened them both. It can be pulled away from the lock body, and I can see a small shaft or pin, which locates into a hole in the lock body. I don’t think it’s a shaft, as its spring loaded and can be pressed into the device, popping out again as soon as pressure is released. It’s about 5mm long. Is it a solenoid? Photo three shows the side of the ignition switch, with the four wire connector mounted on it. Two of those wires go to this device. As seen, I have unplugged that connector; I think the wires for this device lead off towards engine bay and the Cobra immobiliser, but that’s only my guess. I drove about 65 miles yesterday with the device unplugged like this, and I don’t think it’s heating up any more, although the steering lock is still getting warm.
Sorry that’s so long. Can anyone identify and advise? Many thanks.

The part with the green wires looks like the key reminder switch, original fit an normal. I can’t recognise the other part from your photos but it looks factory fit to me.

It definitely seems to be that part that is getting hot; unplug it, as in photo 3 above, and it stays cool. And the car runs normally. Could I remove it? What’s happening with that small pin/shaft locating into the steering lock? I’d like to a) identify it, b) remove it, c) replace it with a new one. Any ideas on that part number in photo 1?
TDS - 12G
8D 24

Jobass, I think you may have missed the most important part of this identification process; the MK2 1.6 is an automatic, isn’t it!!

1 Like

If it’s an automatic …

Taken from the 1999 Miata workshop manual.

Oh, now I’m feeling foolish; I didn’t say it’s an automatic. Thank you rhino666 and Bob_M1. I now have a positive identification. Unfortunately I’m in alien territory, knowing nothing about this key interlock system. I’ll check tomorrow if the Park position is locked when I unplug this. Should the solenoid get hot? Are new ones available? I couldn’t find it on ebay just now.

I think this solenoid prevents you from removing the ignition key unless the gear selector is in ā€œparkā€. There’s another solenoid that stops you moving from ā€œparkā€ unless the brake pedal is down.

If it’s getting hot, it sounds like the solenoid may be operating continuously. There may be a fault somewhere.

Not sure how this works, but the wiring diagram shows a ā€œkey interlock unitā€ in addition to the solenoid. This may be an electronic gizmo that momentarily operates the solenoid. If it’s failed of there’s a broken wire or bad connection, this may be the problem. See

Do you have a voltmeter to check it?

Well, thank you everyone, I’m happier now I know what this is. It’s clearly energised all the time to get so hot. It does indeed prevent key removal in anything other than park. It’s going to remain unplugged for now. The fault is probably elsewhere, as Bob suggests. Where is that key interlock unit?
Now, however, the airbag light is flashing. I can’t imagine that’s a related problem. Or is it?! Clockspring was replaced to deal with that only last year. Oh well, good timing as it passed it’s MoT last week. Maybe time for another spell with the little steering wheel and the 3 ohm resistor!