Speedo whacky, but I've changed everyyyything!

[MikeyD]

My buds cars speedo went nuts, he said he hit a bump, and his lights started dimming, rpms weren't consent. I know a lot about the sixth gen civics, but cant figure it out! We have replaced the alternator, the fuse, the vss, the battery..... all grounds are good... If I remember correct, he has ecu codes for a exhaust recirculation flow malfunction, so that part was also replaced, and still getting the code, he has an o2 sensor code, and irregular voltage code. Now a few weeks later, the speedo wont work at all, and car is a dog, my thought is because Vtec wont kick in because if I am correct it needs the feed from the vss... I hate to be redundant about these stupid speedos, but idk what else I could possibly do!
Its a 1998 Honda Civic Hx 5-speed

 

[RonJ]

Click the Fuse 15 TSB in my signature.

 

[sohclubkid]

also, check the power and ground on the battery and the wires going to the underhood fuse box. also make sure the ALT is plugged in all the way.

my speedo went nuts on me for a few days once. it was a loose ALT plug and loose positive BATT terminal.

 

[619CIVIC]

Check the wires on the plug under the car by intake manifold bracket. Fuse #15 is probably blown too.

 

[XpL0d3r]

Had this happen to me before, was fuse 15. Replaced it, and it blew again. Was that stupid intake manifold recall issue (Fuse 15 Service issue)... Check RonJ's link!