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Honda Accord Speedometer drop to zero randomly and immediately come back to normal

I have 1999 Honda Accord LX, 185000 mile, with 4 cylinders. Starts one month ago, the speedometer drop to zero randomly and immediately come back to normal on highway several times. Recently, car stops twice on street. Dashboard panel had no power. It seems electricity shuts off. I turn the key to OFF and turn the key to ON immediately then the car starts OK. The ignition switch was changed since there was a recall for it. Is there anyone known what is wrong with my car?

The tach is electric, not mechanical, so the needle drop is just another symptom of your overall electrical problem. Since the ignition switch was just replaced I’d suspect a defective switch was installed. Take it back to the dealer that installed the switch and see what they say. I think the fix might be a new and hopefully not defective ignition switch. One of the connectors into the ignition switch might not be making full contact which is related to the installation of that new switch.

I have a 91 Honda Accord (automatic) with a similar problem.
After driving a while the Tac, Speedometer stop working and the radio cuts in and out.
The car still runs, just a little rougher. When I turn it off it won’t start, acts like the battery is dead.
After it sits over night it starts right up and runs fine for a while then does it alover again.

Does anyone have an idea as to what’s going on?

Suspect a bad ignition switch.

To kenG, These same symptoms happened to me too, I have the same year accord. I’m not sure how to fix the speedometer dropping yet, however the rough engine idle and the car not starting after you shut it off, then waiting over night sounds like your Main Relay going bad. The Main Relay controls your fuel pump and when the solder points on its circuit board get old, they start to develop small cracks in the solder points. When car is cool or cold from sitting over night those solder points shrink making the electrical connection successful to turn the fuel pump on when you turn the battery on before starting the car. You can actually hear the pump ‘click’ on when you do this. However, as the car heats up, especially on a hot day, those solder points start to separate causing the electrical connection to be spotty at best, thus not allowing your fuel pump to turn on and your car cannot start if the fuel pump doesn’t go on. These Main Relays are relatively easy to fix if you’re comfortable with some awkward positioning under your dashboard and soldering. Look up the location of your vehicles Main Relay, which is under the driver side dash board on this generation accord. It is a small electrical box you can unplug, while the battery is disconnected of course, then open the plastic case and inside is the Main Relay circuit board. If you look closely, or use a magnifying glass you’ll see some of the solder points have what appear to be ‘rings’ at the base of the ‘Hershey Kiss’ (the solder point). Use a solder gun and lightly touch each of those points with the ‘ring’ to re-connect that broken connection. If you’re not comfortable soldering, bring it to an electronics professional who does soldering to fix circuit boards. I did this on mine and it starts any time and i don’t have to wait for it to cool down like i used to. Good luck!

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You need a new main relay. Just type “99’ Honda Accord Pgm/fi main relay” in an internet search, to see the actual part. This is a very common item that needs replacing and will do precisely what you describe. Its pretty much textbook.