I just replaced the engine in my sons 94 EX (VTEC). It had a slight head leak & he forgot to check the water & roached the engine. put in a 125k mile engine. Seems to run good, but on my test drive, the D4 started flashing I checked the code & the TCU (D4) flashed with 1 & 2.
I could not find TCU code 12 in the service manual or anywhere online.
Was pretty sure I connected everything properly. Will double check tomorrow when I get the time.
Anyone know what 12 is? The manual skips from 1-1 to 1-3

 

I don't see a code 12 either for the TCU. Was the 1 a long flash? And the 2, two short flashes? How much time was between the 1 and 2 flashes?

For comparison, unplug the EGR valve. This will cause the check engine light to flash a code 12.

 

There isn't a TCM code 12 listed in the service manual. Is there a long blink, followed by two short blinks, then a pause for about 1 second and repeating the same? Or is it just one short blink, pause for about 1 second, and then two short blinks?

Short blinks are single digit codes 1 through 9. A preceding long blink and then short blink(s) would indicate double digit codes (e.g., 10, 11, 13, 14, 15), followed by a pause for about 1 second.

Is the first blink long or short?

1 long blink, pause for about 1 second, 2 short blinks, repeat sequence = codes 10 and 2
1 short blink, pause for about 1 second, 2 short blinks, repeat sequence = codes 1 and 2
1 long blink, 2 short blinks, pause for about 1 second, repeat sequence = code 12 (which is not listed in service manual)

You may have a codes 1 and 2, or a code 10 and 2.

 

After reading in the manual a little more, I saw where if it was code 12, the 1 would be a long blink, but I have 1 short blink with about a second delay before the 2 short blinks. Looks like I have converter lock-up issues ? ? ?