Removing immobiliser with stock ECU - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to   Members

ECUs and Tuning Discuss Engine Management, Tuning, & Programming

LinkBack Thread Tools Search this Thread
Old 03-30-2016, 09:31 AM   #1
Junior Member
Thread Starter
Join Date: Oct 2015
Location: Stockholm, Sweden
Posts: 70
Total Cats: 9
Default Removing immobiliser with stock ECU

I just realised my european 1997 NA MX5 has an immobiliser in it. A Temic unit (picture attached), from what I understand the same one as is found in later NB's. I'm installing a megasquirt in a month or two, but I would like to be rid of the immobiliser even on the stock ECU if possible. I expect to have to go back and forth between ECU's a couple times while sorting out various "do you know what the **** you're doing" issues, and it's just one more hassle.

What little info I found on pinouts and such was from here:

I tried unplugging it and jumping the two pins in the connector to feed power to the ignition coil pack (D and L in the diagram, via a fuse), but the car won't start. That would mean that it's not just the immobiliser itself preventing a start, the ECU (PCM) also doesn't want to run unless the immobiliser says it's ok and the rfid in the keys match and whatnot. Which makes sense, without that the immobiliser would be fairly easily defeated.

From what I understand US Miatas didn't get an immobiliser until the NB, so not all stock NA8 ECU's should require one. Is it possible/feasible to make my ECU not care about the immobiliser?
Alternatively, is it possible to run the car on an aftermarket ECU with the immobiliser (i.e. does the immobiliser check the serial of the ECU or something)?

Once I go to the Megasquirt, is this a correct&reasonable way to do it (jumping those two pins)? If I were to do that permanently I'd splice the wires at the immobiliser connector (and unplug it). Maybe install my own "kill switch" like a proper ricer. Might also use the leftover dashboard light for some other function.
Attached Thumbnails
Removing immobiliser with stock ECU-immobiliser.jpg  
jstck is offline   Reply With Quote
Old 03-30-2016, 09:59 AM   #2
iTrader: (76)
18psi's Avatar
Join Date: Apr 2008
Posts: 36,197
Total Cats: 2,584

once you go ms, you don't need it at all, and you shouldn't even need to remove it. it just wont be used.
but while you're on stock ecu, you wont be able to get around it (the ecu and immob interact and it's not a matter of jumping wires)
18psi is offline   Reply With Quote
Old 03-30-2016, 10:30 AM   #3
Supporting Vendor
iTrader: (10)
Reverant's Avatar
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,441
Total Cats: 198

You can't remove the immobilizer with the stock ECU.

The immobilizer on the NA8 and NB1 don't cut the ignition coils or anything, the stock ECU does.

The car will run fine with the MS and the immobilizer still in place but you may get an immo light after about 2 minutes
Reverant is offline   Reply With Quote
Old 03-30-2016, 05:14 PM   #4
Junior Member
Thread Starter
Join Date: Oct 2015
Location: Stockholm, Sweden
Posts: 70
Total Cats: 9

Ah, so the stuff in that PDF about the immobiliser de-powering the ignition coil is not correct (for my particular car)? Good to know. Once I'm set with the MS, if it lights up the warning light I'll just unplug the immobiliser.
jstck is offline   Reply With Quote
Old 03-30-2016, 05:27 PM   #5
Boost Czar
iTrader: (61)
Braineack's Avatar
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,896
Total Cats: 1,792

Yeah the ecu just won't run the car if it doesn't get the correct signal back from it. Remove the ecu and it's not a problem, just deal with th the light, unplugging unit will probably work
Braineack is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Help with LC-1 / Megasquirt wiring, lots of pictures, tell me what I did wrong. miataa DIY Turbo Discussion 56 04-08-2016 02:55 PM
1997 Mazda Miata STO #1189 - $$4500 ZNuT Cars for sale/trade 1 04-18-2010 10:57 PM
What is normal voltage sent to trigger MX5 coil packs? bompus Engine Performance 0 11-02-2009 08:36 PM
Found a ubercharger for cheap, now what to do... greddymx5 DIY Turbo Discussion 6 08-15-2009 09:10 AM
Car is running!! but.. new problems arise. Inj Lag times found! NB owners look! Marc D E-Manage 10 09-17-2007 04:23 AM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -4. The time now is 03:04 PM.