Hi everyone!
Right after a bad crank pulley and an MAF sensor that took the car sitting for 3 weeks, I have been blessed with the RCM / K40 symptoms (dash and lights working but no crank and within few seconds motor Fan running like a P-51 Mustang while taking off) (and surprisingly disabling OBDII recognition by my diagnosis tool (Launch 129x pro, always recognizes VIN when plugged to the car and start diagnosis)).
After this event, occasionally no crank isolated symptoms that I didn't gave relevance (usually turned key off and on and started right away).
So turns out
I'm in need of a new Engine Control Relay*
After magnifier inspection and resoldering of almost every contact point, and checked continuity between tracks, I tested each relay with a 9v alk battery, all closing but Engine Control relay #3 (center one), though visual inspection seemed ok (no brownish discoloration, no carbon buildup), also IPA cleaning and sanding contact points didn't work.
Module mounted in car, I tried the rubber band trick with great results, car started in a breeze, no codes stored in ECM).
As American Zettler-AZ970E-1A-12D is almost impossible to find where I live without paying an absurd amount of money, and while I search for another candidate** for soldering in place of the bad relay,
I thought that a simple solution would be to jumper the relay with some sort of analogic switch, acting as a Killswitch, mounted in the cabin, or in a "secret" place, as an additional security measure.
To be actuated by hand right after turning key to ACC, before cranking, or even before inserting the key, just like the rubberband trick did
Could this be done without damaging the ECM, SKREEM or any other electronic module? (Maybe because electrostatic when switching or something that my sparingly knowledge of electronics didn't thought about)?
And even overcomplicating it (I'm always disregarding the KISS rule -Keep It Simple, Stupid :P),
could that Engine Control Relay be substituted by those generic battery Killswitches (200A, 12vdc SPST NO relays that can be activated through a 433mhz remote)?, and stuffed into RCM box to go completely undercover (pun intended).
Given that #3 relay disables completely cranking, OBDII tampering, and also runs fan in a deterrent way to anyone wanting to run away with the car unnoticed, and also that my siren went bad (didn't bought another one yet), and having in my near-future to-do list of XFire mods an SKREEM delete (through one of the various options listed in this marvelous forum, when the budget jar is full again), I'm a bit concerned about how vulnerable I would render the car with all this mods that overrides security, so, just to be cautious.
Thanks in advance, have a nice ride!!
**Possible RCM relay candidates:
Since RCM modules can go up to +100$ shipped to my place, and I'm short of budget atm, I thought to buy and salvage Pulse Module relays (can get the PM about half the price or so).
Also found in the comments section of a YouTube vid (htt ps://youtu.be/spTx0k3_PI0?si=3T0zRpDaQMU202vH) a list of candidates by the user antdavisonNZ that I'll copy-paste here if is useful for anyone, if possible to be confirmed by the experts or by comparing data sheets.
Euro footprint, 90ohms 1.6w:
Tyco TE Omron P&G OEG Schauk -- V23076
Multicomp HKE CMA4
Song China -- 822
Fujitsu Takimisawa -- FRL-274
CIT --- A5 (a51ae12?)
I will summon all the 2 legged pools of crossfire knowledge that I can remember just in case. All opinions are welcomed!@tighed1 @pizzaguy @GraphiteGhost @zip439 @onehundred80 @Valk @Viper-666