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D4 light flashing on Honda Accord

I have a 95 Honda Accord V6, the D4 light is flashing and the speedometer needle does not work. When in stop and go traffic, the needle bounces around and makes the car stall and downshift and rev up. I replaced the speed sensor with no change. Can someone help?


  • A blinking D4 light is like a check engine light for the transmission. Regular code readers like the ones used by AutoZone will not read the transmission codes. You will need to take the vehicle to a dealer or a trusted transmission repair shop.
  • Sounds like a transmission problem. First thing would be to check the transmission fluid level. Does Honda suggest periodic replacement of the transmission fluid along with cleaning the transmission filter/screen? If so, that would probably be the second thing. The third thing is to anticipate a significant budget item coming up soon.

  • As the Honda Owner's Manual tells you, a blinking D4 light indicates an electronic problem relating to the transmission. And, it also states that failure to fix the electronic problem promptly can lead to more expensive mechanical problems. In other words, don't continue to drive it. (If you don't have an Owner's Manual, this is a perfect example of why you need to get one and to read it!)

    In this case, the fix could be as simple as replacing a Vehicle Speed Sensor (VSS), or it could be as expensive as replacing the Transmission Control Module. Only examination by a competent mechanic can tell you for sure. I suggest that you take the car to an independent transmission shop for an accurate diagnosis. Whatever you do, DO NOT go to AAMCO, Lee Myles, Cottman, Mr. Transmission, or any other chain operation unless you want their standard diagnosis of, "You need a new/overhauled transmission".

    When the car is at the trans shop for diagnosis, I suggest that you also have them change the fluid and trans filter if those procedures have not been done in the last 3 yrs/30k miles.
  • The filter is not serviceable on this transmission, its strictly drain and refill, NEVER flush. VDCdriver is correct, get this checked before it becomes a bigger problem.
  • Since you replaced the VSS, I guess you are a DYIer, so here is the information you need to troubleshoot this yourself.

    Under the dashboard on the passenger side right next to the kick panel, you will find a plug with two wires going to it. It should have a cap on it but it might be missing. This plug is not plugged into anything. The wire colors are red and green/blue. Short the two pins of this plug with a short piece of wire or paper clip.

    Turn the key to the on position and the D4 will blink a code.

    One short blink = lock up clutch does not engage/disengage or unstable idle speed. Lockup control solenoid valve A

    Two short blinks = lockup clutch does not engage. Lock up control solenoid valve B

    Five short blinks = fails to shift other than 2nd and 4th gears, lock up clutch does not engage. Short in A/T gear position switch or wire.

    Seven short blinks = fails to shift 1-4, 2-4 or 2-3 or stuck in 4th gear. Shift control solenoid valve A or wiring.

    Eight short blinks = fails to shift, stuck in 1st or 4th. Shift control solenoid valve B or wiring.

    Nine short blinks = Lockup clutch does not engage. Countershaft speed sensor or wiring.

    One long blink and five short blinks = Transmission jerks hard when shifting. Mainshaft speed sensor or wiring.

    Four long blinks = Lockup clutch does not engage/disengage or idle speed unstable. Faulty lockup control system.

    Four long and one short blink = Fails to shift 1-4, 2-4 or 2-3 or stuck in 1st or 4th. Faulty shift control system.
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