Error code d4 - Tyan Computers & Internet

Flashing D4 light is an error from the TCU (transmission control unit), so you got something going on with your transmission. If you want to pull the error code, remove the passengers side kick panel and look for a pair of wires with a blue connector at the end. Stick a paper clip or some other piece of wire into each hole of the connector to short the wires. Put your key in the ignition and turn 2 clicks. The D4 light will flash the code...short flashes=1 and long flashes=10. Add the number of short and long flashes to get your code. Errors are below:

0-Transmission control unit (TCU) faulty.
1-Lock-up solenoid 'A' circuit open or shorted.
2-Lock-up solenoid 'B' circuit open or shorted.
3-Throttle Position Sensor circuit open or shorted.
4-Vehicle Speed Sensor open or shorted - No signal from speedometer.
5-Shift Lever Position Switch circuit shorted.
6-Shift Lever Position Switch circuit open.
7-Shift Solenoid 'A' circuit open or shorted.
8-Shift Solenoid 'B' circuit open or shorted.
9-Counter shaft or transmission speed pulse generator open or shorted.
10-Coolant Temperature Sensor open or shorted.
11-Engine RPM (Ignition coil signal) open or shorted.
12-(No code 12 used)
13-Main shaft speed pulse generator open or shorted.
14-Linear (line pressure control) solenoid open or shorted.
15-Kick down switch circuit shorted.

Hope helps.

The D4 light is coming on to tell you that there is one or more fault codes set in your transmission control module. The only way to retrieve codes on the 1995 models is to read "Flash Codes" output by the D4 light. (See instructions below)

RETRIEVING FLASH CODES USING THE D4 LIGHT
If fault codes are present, the D4 light will "blink" when the ignition is turned to the RUN position and will remain on at all times when the engine is running.
To retrieve the flash codes, turn the ignition switch off.
Install a jumper wire between the service check connector terminals.
The service check connector is a gray, 2-pin connector located on the PCM/TCM cover under the passenger side of the instrument panel. (See picture below)

CAUTION: DO NOT use the 3-pin located next to the service check connector.

Installing the jumper will place the PCM/TCM in diagnostic test mode.
Turn the ignition to the RUN position. Codes will be output by blinking the D4 light.
Note the number of blinks from the D4 light. A short blink indicates a single digit flash code. A long blink equals 10 short blinks. For instance one short blink indicates code 1. One long blink and four short blinks indicates code 14. If there is more than one fault code, they will be output one at a time from the lowest numbered code to the highest numbered code. It is recommended that you read the code or codes several times to make sure that you are reading it correctly.

Once you have retrieved the fault code(s) re-post your question and include the information for what codes you have and someone can then help you locate the cause of the problem.

There are many other things that cause the D4 to flash. The D4 light turning off is similar to the CEL turning on. Some codes cause the light to blink, some turn it off. There's an error code stored, pull it and start from there.

Check this DIY: Diagnosis: Pulling Codes

Definitely pull all the codes and let us know what you find. Once we know what the codes are then we can help you troubleshoot the issue/s. Alot owners talk about VSS (Vehicle Speed Sensor) but the VSS may or may not be part of the issue but per your description it may sound like a main relay to a tranny issue.

Keep us updated.

D4 light on indicates automatic transmission malfunction or servicing needed, corroborating the problem you explain. Have the vehicle scanned by a Honda dealer, and with the error code in hand, decide on a solution or obtain additional quotes from other sources.

Flashing D4 light is an error from the TCU (transmission control unit), so you got something going on with your transmission. If you want to pull the error code, remove the passengers side kick panel and look for a pair of wires with a blue connector at the end. Stick a paper clip or some other piece of wire into each hole of the connector to short the wires. Put your key in the ignition and turn 2 clicks. The D4 light will flash the code...short flashes=1 and long flashes=10. Add the number of short and long flashes to get your code. Errors are below:

0-Transmission control unit (TCU) faulty.
1-Lock-up solenoid 'A' circuit open or shorted.
2-Lock-up solenoid 'B' circuit open or shorted.
3-Throttle Position Sensor circuit open or shorted.
4-Vehicle Speed Sensor open or shorted - No signal from speedometer.
5-Shift Lever Position Switch circuit shorted.
6-Shift Lever Position Switch circuit open.
7-Shift Solenoid 'A' circuit open or shorted.
8-Shift Solenoid 'B' circuit open or shorted.
9-Counter shaft or transmission speed pulse generator open or shorted.
10-Coolant Temperature Sensor open or shorted.
11-Engine RPM (Ignition coil signal) open or shorted.
12-(No code 12 used)
13-Main shaft speed pulse generator open or shorted.
14-Linear (line pressure control) solenoid open or shorted.
15-Kick down switch circuit shorted.

D4 light indicates some sort of malfunction or needed service for the auto transmission. Take the vehicle to a shop where it can be scanned, and see what error code comes up.

yes it will matter that the switch is v tec....AND I WOULD REPLACE THAT SHIFT SOLENOID AS WELL ...THE THROTTLE POSITION USUALLY ISNT THE PROBLEM WITH THIS PARTICULAR MODEL..first the v.s.s and the shift solenoid is most likely the culprit

why does the d4 light start to blink and it doesnt stop even if you put it in park?

A flashing D4 light means a transmission error code is stored in the cars computer.

Is could be something as simply as a cable adjustment.

Without knowing the actual trouble code, it's hard to tell.