Hi guys , been doing my best to track this down. I have a 93 accord lx, 230k, recently had timing belt replaced as usual maintence. Driving home the other night on the highway, d4 started blinking, no apparent change to drivability. Checked next morning, didn’t come on for two miles, possibly after high idle came down? Warmed up? Still no change in drivability. Drives fine. Checked codes by shorting access plug. No codes, no blinking, cel light on in ign ll , as is everything else. I’m at a loss. Thoughts? Btw tack has been erratic for some time.

 

Just a bit confused. Does the D4 light start flashing after the car warms up all the time, or just the one time?

 

Intermittent at this point, however just might be due to short trips. Went about 2 miles, three miles yesterday, nothing, as soon as I started up to come back. There it was. Today out a bout two miles nothing, come back nothing…

 

This is a tough call. If the check engine light isn't turning on while driving and you are not getting any codes from the check engine light or the D4 light, I suspect something is going on with the TCU. I wouldn't worry about it unless you have some driveability issues or something stops/isn't working. You might want to check the 7.5 amp backup/radio fuse in the engine bay fuse box and any TCU fuses.

If you want to address the tachometer, we can give you some tips if you plan to DIY work. I'm assuming the actual engine rpm isn't having an issue.