my car is a 1994 accord with a automatic prelude engine and transmission. my d4 light will start flashing half the time when im driving and when it does that my car will start getting less power when it drives. i remember my step dad stuck something down in one of the clips on the wire harness for the transmission computer, i think maybe one of the wires is loose, and for a month or so it was fine but then started back up. do i just need to get another harness for the tcu? also my car is still running on the accord ecu instead of a p28 or p13 so i thought i should mention that just in case.

 

If your car is using the Accord harness still, check under/below the glove box door.
Pull down the two wire blue connector.
Jumper the connector with a wire.
Turn ignition to II(ON).
Watch the warning lamps for blinking and record codes.
Post back here.

 

it flashes once then four quick flashes. first one is a little longer then the other four. idk why but for some reason i only thought that was for the check engine light.

 

14. FAS-wire *D4 does not light*

That is the communication wire between the ECM and TCU.
Most likely your dad knows and did a temporary fix.

 

so then i just need to replace the wire harness for the tcu?

 

No.

If the communication wire is not making a connection, fix the connection. If your dad had installed a pin to tighten a connection and that pin has fallen out, then most likely it is that same pin/connection that needs attention. No need to replace the harness, just fix the bad connection. It may be either from corrosion, dirt, or just a loose connection that needs to be addressed.

I don't have an FSM in front of me so I can't tell you what color wire, or pin numbers they are for easier checking. I *think* the FAS is a brown or beige wire wire, probably with a white strip, and I *think* it was A8 or A18 on the ECU. This wire will be connected to the ECU and TCU.

 

so then just replace the wire or the clip? if so any idea where i would get it or would most shops have them?

 

Locate the wire and note if it is looser in the connector than the others, if it is then its just a bit sloppy and needs to be adjusted for a tighter fit. Remove the harness and inspect the connection itself, if it is corroded then that would cause no conductivity and your current fault issue. Electrical contact cleaner is some good stuff.

Inspect and diagnose.

 

I currently do not remember how to make a post but i was wondering if you knew what the best ecu and chip/program would be best foru keeping it automatic.