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Discussion Starter · #1 ·
Hi everyone,

I'm finishing my old K20A2 swap to K24.
Last weekend all the pins from the Mitch Auto Parts adaptor broke off, so what i did was i tapped into the correct plugs.

Because i wasnt sure about what goes where i followed this video


Based on the video above I have, i included the connector and marked the pins based on ECU Master's information, screenshot below

Green Font Material property Parallel Rectangle



I got the Honda part from here:

Font Parallel Art Document Screenshot


E2 (black plug)
Electrical wiring Computer hardware Cable Gas Electronic engineering

From: Honda E Plug (IG1, Pin 9)
To: Pin 8, IGSW (black wire with red line)

From: Honda E Plug (K-Line, 23)
To: Pin 27, TACH (white wire single dots)

From: Honda E Plug (Mil, Pin 31)
To: Pin 15, MIL (yellow wire Red line 2 dots)


From Honda E plug (FPR, Pin 1)
To: Pin 3, FC (Green wire red line)
Problem: doesn’t turn / prime fuel pump
Also: to fuel pump relay trigger



E3 (white plug)
Electrical wiring Electrical supply Wire Electronic device Wrist

From: Honda E plug (Main Relay, Pin 7)
To: Grey (EFI Main relay)
Problem: P0563 VBU High Voltage
Try: swap EFI relay with horn -> Did not fix the issue


From: Honda E plug (RPM, Pin 26)
To: C101 Pin 17

From Honda E Plug (Speed sensor, Pin 25)
To: C101 Pin 17

From Honda E Plug (BKSW, Pin 22)
To: Pin 6, STOP (Green wire single dots)



However, even if i dont start the car i keep getting this error
Rectangle Font Screenshot Parallel Software



the car starts but also randomly dies between 20 seconds and 2 minutes like the ecu is losing power? because it asks me to re-connect.
Sometimes ECU becomes offline after that for a while.

Based on all my google results it means that: EFI / main relay is getting power without going to the proper channels?
Also what i have noticed is that the E1 pin (FPR/Fuel) should allow me to trigger the external fuel relay trigger wire which it does not (no prime) but when i connect this wire (blue on my relay) to a button like i always had it works fine but keeps the pump on so i have to turn this off.

Not sure if this is related or not but i noticed it.


I wonder if anyone with the untouched map harness could double check the pins or knows thats going on?
I didnt touch the relay box as my car was driving with the K20 so I only tapped into the white and black plug from the E loom.

The rest of the map loom is untouched as those pins seem fine.

Thanks in advance
 

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Discussion Starter · #3 · (Edited)
Your main relay wiring is most likely incorrect.
The order is battery 12V ---main relay coil--- ECU E7

So with ignition on, but E plug unplugged, E7 should show battery voltage.

These schematics are very helpful:

Complete Trouble shooting is in the Acura RSX-S manual section 11-194.
Thanks ill check that.
The MR2 doesnt have a main relay as far as I know and we use the EFI relay for that (MREL in the Ecu master list)

which i had to mod (did that as k20 was working)

ill check trough the list
 

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Essentially the ECU sees 12V on E9 when you switch ignition on.
It then checks if Pin E7 is at 12V. If not, you get that error.
If all right, the ECU pulls E7 to ground to activate the main relay. If the coil drive current is too high, e.g. from a bad relay, you get an error as voltage on E7 does not drop to GND level.
Next, the ECU checks main relay activation as it now should see 12V on C101 14 Power Supply or ECU A2, A3 where C101 14 leads to.
If that fails, you get your error. If that is all good, it will pull E1 to ground to prime the fuel pump.
 

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Discussion Starter · #5 ·
Essentially the ECU sees 12V on E9 when you switch ignition on.
It then checks if Pin E7 is at 12V. If not, you get that error.
If all right, the ECU pulls E7 to ground to activate the main relay. If the coil drive current is too high, e.g. from a bad relay, you get an error as voltage on E7 does not drop to GND level.
Next, the ECU checks main relay activation as it now should see 12V on C101 14 Power Supply or ECU A2, A3 where C101 14 leads to.
If that fails, you get your error. If that is all good, it will pull E1 to ground to prime the fuel pump.
thx ill check after work.


e7 was 0v with ignition on just now

ill check:

e9
C101 Pin 14
 

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Discussion Starter · #11 · (Edited)
"if unplugged, e7 must show 12V with ignition on" with the plug unplugged on the plug, not the ECU!
sorry my mistake, ill disconnect E7 from the plug itself (cable is just connected by tape to test)
ill check again

Don’t have enough charge to start the car but the error is gone!

However E1 to my external fuel relay isn’t triggering it still for some reason.
 

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you can „diagnose„ if the ECU works by fitting a small glow bulb (1-3W) or a 12V LED between 12V and the E1 pin. The bulb should glow for 2-3 seconds as the ECU primes the fuel pump upon powering up.
If this is positive, likely, then work your way from there, so cable to relay, relay itself, power feed to relay coil, power path from battery though relay, fuse, and pump to ground.
 

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Discussion Starter · #14 ·
you can „diagnose„ if the ECU works by fitting a small glow bulb (1-3W) or a 12V LED between 12V and the E1 pin. The bulb should glow for 2-3 seconds as the ECU primes the fuel pump upon powering up.
If this is positive, likely, then work your way from there, so cable to relay, relay itself, power feed to relay coil, power path from battery though relay, fuse, and pump to ground.
Thanks good one, i did this for the MIL light (big white led strip on top of my ecu) but good idea to do/test this for the fuel prime as well
 
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