Thread: please help im pulling my hair out! Tach adapter went bad?!

So sat night pulled up to the atm the ecu loses power, the car stops running but it still on....ok wtf...it wont start so i get it towed home. This morning im digging through the wiring, testing all the fuses, but for some reason my ecu will only turn on if i tap the relay and will not turn back off even with the key out unless i unplug the relay. I tried 4 different relays and same result. I took my ecu and stepdown harness off and tried the stock ecu just to see if it will turn on/off like it supposed to and it did! WTF!!! Ok so not a problem with my engine harness, so problem with the stepdown harness maybe, ECU is showing a code 21 ignition signal primary....I do have a msd ignition, maybe my tach adapter went bad all of a sudden?

What do you guys think?

Ok - so this is where we all become mind readers ? Right ?

I'm guessing you have a B14 with a B13 ECU ?

What ECU ?

What has been modified?

What Engine ?

Give us some more idea of what you are working with.


Sorry but I have to be able to visualize it to figure it out - I'm not smart like that.

yes...
sr20ve-t
ecu is a calum realtime v1
msd digital 6 and 8010 tach adapter
stepdown harness b14->b13
apexi vafc and avcr wired into the stepdown harness

the code 21 makes me think its an dizzy/tach adapter issue but doesnt make sense why the ecu sees power when i tap the relay without the key.
im trying to source another b13 ecu to test to eliminate an ecu issue since it works fine without the stepdown harness.

It's a pretty simple diagnostic. Here is everything that you should need to figure it out.

Code 21 - Ignition Signal Diagnostic Chart

Circuit Diagram

Connector Location

the thing is without realtime and stepdown harness the stock b14 ecu it turns on and off perfectly fine. So now im convinced theres an issue with the stepdown/ecu.