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Hey guys,

Bit of a noob question, but I seem to be having trouble with the immobilizer fitted to my 1990 NA6.

I have searched high and low and can't seem to find any information on factory fitted immobilizers for the 1990 NA6, which makes me think it must be aftermarket. It all started after disconnecting the battery while overseas and re-connecting when I got back.

Awesome trip to JDM land:


Anyway....
After plugging the battery back in, or after a few minutes or turning the key past ACC, the hazards/indicators start flashing and won't stop. Regardless of engine ignition, the hazards continue to flash, as does the little red LED on the steering column.

Haven't tried driving it out of the garage yet, but im guessing the engine may cut out if i do.

Haven't had time to trace wires fully yet. But i've taken down all the steering trim and really quickly tried to trace the red LED on the steering column to look for a control unit, but haven't located anything just yet.

The car doesn't have central locking or remote/keyless entry. It's purely old school key entry, of which I have about 6 copies from the previous owner, but none appear to be originals (not that a car this age would have immobilizer chipped keys).

Pretty sure its something that can be figured out and will go back down later and trace wires, etc. But in case anyone knows anything offhand (like the ancient immobilizer in my old hachi had a unique key and a weird 20 turn sequence to bypass it), any help would be appreciated. Cheers guys.

trim on, arrow to the light thats flashing

Aust domestic market NA6 didn't have an immobiliser fitted from the factory, & I don't believe the early Japanese domestic market NA6 did either. Is your NA6 ADM or JDM, i.e. 'JM0NA' or 'NA6CE' in VIN?

the man said "I seem to be having trouble with the immobilizer fitted". An often repeated phrase. Apart from whether its worth having them at all, if you do the best bet is go to a specialist on immobilisers. In my area there is a bloke who sorts this out and apparently at a decent price. The problem for many of us- ie like me- is that we do not understand enough or anything about electronics or the previous owner did not either but still fitted it. These things just go past the reliable stage and a dead car is not a good look. I would expect 93 is right- its an aftermarket unit.

Thanks for the reply guys.

93_Clubman wrote:Aust domestic market NA6 didn't have an immobiliser fitted from the factory, & I don't believe the early Japanese domestic market NA6 did either. Is your NA6 ADM or JDM, i.e. 'JM0NA' or 'NA6CE' in VIN?

AUDM. Having looked around now, definitely aftermarket. Ancient aftermarket though, and absolutely no markings on the unit, except for a code 1873 that appears on the box and on the chipboard itself. After googling around, the only immobilizer i could find is a Wheels 3-way BA5000 unit. But it's not that one.

Mr Morlock wrote:the man said "I seem to be having trouble with the immobilizer fitted". An often repeated phrase. Apart from whether its worth having them at all, if you do the best bet is go to a specialist on immobilisers. In my area there is a bloke who sorts this out and apparently at a decent price. The problem for many of us- ie like me- is that we do not understand enough or anything about electronics or the previous owner did not either but still fitted it. These things just go past the reliable stage and a dead car is not a good look. I would expect 93 is right- its an aftermarket unit.

Lucky the car is a bit of a project and I rarely drive it. I'll try to tinker myself for a bit when I have the time, but in the end I may need to call one lol.

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Okay so today was the first time since OP that I've been down to take a look at the car.

Tried plugging battery back in a starting it. Would crank but not fire? I assumed it was still coz of the immobilizer.

So I went to take a look at removing the immobilizer, carefully marking what wires went where. I removed the steering surround and the panel directly beneath and traced the wire of the flashing immobiliser LED.
Found a little black box with several wires all connecting to the ignition harness and loom directly back from that.

Turns out none of the wires were actually re-routed, only spliced/bridged mid-wire (T-connection) from the ignition loom/harness into the little black box.

I was able to remove the immobiliser box and the bridged wires while retaining all OEM wire paths.

This is the immobiliser unit I removed:


There don't appear to be any buttons (e.g. some units have a button to reset, etc). There is however that long black piece to the top right which rotates, e.g. im thinking its like those alarm systems with vibration sensitivity. Although this car didn't ever seem to have an alarm.

Wire 1 - to LED negative
Wire 2 - (blank)
Wire 3 - to ignition harness
Wire 4 - (blank)
Wire 5 - ground
Wire 6 - to ignition harness (further back down the loom), spliced into green
Wire 7 - to ignition harness (further back down the loom), spliced into green/white
Wire 8 - to LED positive (but also a T into ignition harness)
Wire 11 - (blank)

There was also another wire from the thick blue wire in the ignition harness that led under the carpet and wasn't connected to anything? so i removed it.

All the wiring on the ignition harness/loom appears stock and in-tact. Can't see anything else thats been cut or running anywhere else + all remaining wires and tape look OEM. Overall it was a very neat removal and I was sure it would start again no problems.

So i plugged the battery back in... and it continued to crank, no ignition.

Ran out of time.
Hmmmmm... will continue tomorrow.

Does anyone know if these ancient immobiliser units have any other wires usually running to the starter motor or anything? Or is it able to immobilise simply with these few wires connected to the ignition harness.

Because it's now only cranking and not firing (like it was just before i removed the unit); I'm not sure if its because of the immobiliser now (or lack of complete removal and remaining wires?), or if its a mechanical reason, e.g. car has not been started for about a few weeks.

Putting the unit back on is a simple matter of bridging back those 4-5 wires so can be un-done anytime.
Let me know if anyone has any ideas.

Can't help re the immobiliser wiring question, but your options are to reattach the immobiliser & try to start the engine, purely to note if there is any difference to trying to start with the immobiliser disconnected. Alternatively, leave the leave immobiliser out & try to diagnose the issue, i.e. determine if it is not starting due to a lack of air, or fuel, &/ or spark. At least then you can focus on further diagnosing a single (fuel or spark), or at most a dual issue (fuel & spark). Obviously air is easy to check & fix as it this is the cause or partial cause it could be because a cloth has got sucked into the air cleaner snorkel. This happened on my old NA6 after it had just been serviced by a dealer.

Btw, when you say the engine was cranking & firing prior to removing the immobiliser (as opposed to cranking & not firing now), did you actually start & run it (obviously without driving it from what you said in your initial post)?

Good to hear at least that the immobiliser was relatively easy to access, remove, & reconnect the original loom.

93_Clubman wrote:Can't help re the immobiliser wiring question, but your options are to reattach the immobiliser & try to start the engine, purely to note if there is any difference to trying to start with the immobiliser disconnected. Alternatively, leave the leave immobiliser out & try to diagnose the issue, i.e. determine if it is not starting due to a lack of air, or fuel, &/ or spark. At least then you can focus on further diagnosing a single (fuel or spark), or at most a dual issue (fuel & spark). Obviously air is easy to check & fix as it this is the cause or partial cause it could be because a cloth has got sucked into the air cleaner snorkel. This happened on my old NA6 after it had just been serviced by a dealer.

Btw, when you say the engine was cranking & firing prior to removing the immobiliser (as opposed to cranking & not firing now), did you actually start & run it (obviously without driving it from what you said in your initial post)?

Good to hear at least that the immobiliser was relatively easy to access, remove, & reconnect the original loom.

Thanks for the reply.

I went down and did a bit more diagnosing today. I'm at the point where I also think that it may be a fuel/spark issue rather than electrical/immobilizer now.

When I made the first post, the car was starting normally after i reconnected the battery once home from overseas (3-4 weeks disconnected and undriven). The only issue was the unstoppable indicator flashing and red LED flashing caused by the immobilizer. I was hesitant to drive it out in case the engine cut like some of the immobilizers do out there.

Yesterday prior to removing the immobilizer I noticed that it was cranking but not firing. At that point, I put it down to also being due to the immobilizer.

Then I removed the immobilizer and it still cranked but did not start.

Today I've plugged the immobilizer back in (reversal was very simple) and it's still not starting, but cranking away happily.

I'm now thinking it may be the fuel pump, as I'm not noticing/hearing any activity when set to ON, even with the parcel shelf metal cover off. Although I cannot remember how obvious the sound of the fuel pump was, I am hearing almost no activity.

I'm going to hit up a multi-meter and check that the signal is going to the pump.

I've checked the sparkies (Bosch plat), leads (Mazdaspeed), dizzy and intake (Jackson Racing). All clear.

Although its odd for the pump to fail with between simple starts (unless it could be due to the repeated fuel pump engagement and stress from me starting and stopping in short succession?) and coincidentally at the time of immobilizer issues. I'm not sure of its age nor when it was last changed, could be 22 years old for all i know.

Thanks for the reply, will update progress and if you get any more ideas let me know. Cheers.

You can certainly check to see if the fuel pump is getting 12v, but it might be better to confirm whether the motor is getting fuel, i.e. are spark plugs wet upon removal & inspection immediately after cranking. I say this as the sound of the fuel pump isn't always evident. By the sound of it you may also still need to confirm if you're actually getting a spark or not.

Ref fuel pump, have a quick look & note the following as it's increasingly becoming an issue on the NA6 & NA8 as they age: viewtopic.php?f=55&t=46425

Meant to also say, is there anything else that you can think of that you've done recently that might be related to the issue you're now experiencing. Coincidence does sometimes occur, but often issues are related to something else we've done.

A quick way to see if the fuel pump is working is to jump the FP and GND connectors in the diagnostics plug in the engine bay (hangs off a bracket near the air filter/AFM). This will cause the fuel pump to remain on when the ignition is set to on.

Good luck.

J.

93_Clubman wrote:You can certainly check to see if the fuel pump is getting 12v, but it might be better to confirm whether the motor is getting fuel, i.e. are spark plugs wet upon removal & inspection immediately after cranking. I say this as the sound of the fuel pump isn't always evident. By the sound of it you may also still need to confirm if you're actually getting a spark or not.

Ref fuel pump, have a quick look & note the following as it's increasingly becoming an issue on the NA6 & NA8 as they age: viewtopic.php?f=55&t=46425

Meant to also say, is there anything else that you can think of that you've done recently that might be related to the issue you're now experiencing. Coincidence does sometimes occur, but often issues are related to something else we've done.

Thanks for the reply and extra link. I inspected the connectors when the fuel pump assembly was out as per your thread and info. The connectors were in reasonable condition. Great tip to watch for. Cheers.

The time it took to take out and change the fuel pump was amazing. I'm absolutely loving the simplicity, access and overall transparency of working of this car. Not to mention the ability to work on a parcel shelf, 1. without ur face pressed against a coupe window or squatting on back seats, and 2. no top on at all!

aka_juffa wrote:A quick way to see if the fuel pump is working is to jump the FP and GND connectors in the diagnostics plug in the engine bay (hangs off a bracket near the air filter/AFM). This will cause the fuel pump to remain on when the ignition is set to on.

Good luck.

J.

Cheers for that, the FP-GND bridge made it a lot easier to multi things and basically diagnose what was and wasn't working.

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Thanks for the replies guys! So in the end... she's up and running again

No immobiliser, new fuel pump, sparkies, AFM inspect/clean and idle air speed adjustment.

Although I wasn't able to pin point the exact problem, seeing as I had a spare weekend (rare nowadays with work), I went ahead and inspected/replaced several items I told myself I would when I acquired the car some 9-12 months ago but never did.

Fuel pump replacement was a breeze. Took a matter of 20-30mins, and took the time to inspect/multi all signals and connectors to the assembly and pump itself. Doesn't help that the half tank of fuel sitting in there is probably some 3+ months old. I need to drive her more!

While I was at it, thought I'd change the plugs seeing as I had no idea how old they were.

Also went ahead and took apart the Jackson Racing intake I'd installed but hardly run since installing. Whipped the AFM off for a quick look and checked the throttle body, etc.

When I finally got it started, noticed that the idle was hunting and dipping on throttle release. Kind of reminded me of my old R32 skyline which had unstable throttle release issues relating to the AFM and BOV (have gotten used to working on my MAP sensored JZA80).

After a quick play around and search, ran the TEN-GND diagnostic bridge and noticed a big difference between idle and bridged idle air speed. I made a few adjustments to the IACV, bringing up the idle to approx 800rpm, removed the bridge and had fixed the instability and idle dip. However, it almost sounds as though the throttle body might be slightly open at idle with the current setting (although it could just be due to the higher air volume and reasonably normal) as im hearing significant induction noise at idle through the Jackson Racing intake. I'm wondering if this is just a temporary fix and why the idle air speed would have changed so much with my few simple parts replacements (ie fuel pump and sparkies).

Anyway, problems all solved, thanks for all the help guys Sorry about the essay, and I'll be glad to take her for a drive and clean in the next few days.

dancoco808 wrote:Whipped the AFM off for a quick look and checked the throttle body, etc.

When I finally got it started, noticed that the idle was hunting and dipping on throttle release.

After a quick play around and search, ran the TEN-GND diagnostic bridge and noticed a big difference between idle and bridged idle air speed. I made a few adjustments to the IACV, bringing up the idle to approx 800rpm, removed the bridge and had fixed the instability and idle dip. However, it almost sounds as though the throttle body might be slightly open at idle with the current setting (although it could just be due to the higher air volume and reasonably normal) as im hearing significant induction noise at idle through the Jackson Racing intake. I'm wondering if this is just a temporary fix and why the idle air speed would have changed so much with my few simple parts replacements (ie fuel pump and sparkies).

Good to hear that you've been able to bin the immobiliser & get the car running ok again.

Not uncommon to find idle changes after cleaning TB, in particular if the idle screw is removed for cleaning. Also, if you disconnected the battery for long enough the ECU may also have had to initially do some relearning which might have had an effect - it would also have cleared any fault codes from the ECU. Ref throttle butterfly sounding like it's slightly open, there's a possibility that a previous owner has used the wrong TB cleaner & has damaged or removed the thin layer of brown sealing compound inside the TB where the throttle butterfly closes on the TB bore.