I have a 99 Civic, while driving one day the speedometer quite working. Took it to have the code read and it said that the speed sensor needs replaced. Before I could get that fixed the alternator went out, replaced the alternator. When that got fixed my check engine light came on, took back to have the codes read and now the O2 Sensors need replaced, but it does not tell me about the speed sensor anymore. In the mean time I have had to replace the battery. Now with a new alternator and a new battery, the speedometer and the odometer want work. The speedometer bounces now, and the dash light blink. HELP!!!

 

A failing alternator can cause all sorts of issues, including making an ECU freak out if voltage gets low enough. Personally, I'd clear the ECU and take it for a spin (or just start it and let it idle, I guess) before going forward much further with diagnosis, to be sure it isn't just false positives stored in its memory.

 

Bouncing Speedo, non functioning odometer point to sensor failure. Unless, you starting cutting up wires and messing with that, the sensor is at fault. The CEL for a VSS (speed sensor) will not come on immediately at start up. However, it will come on after driving a little while. When mine was not working, the CEL would come on after getting up to or over 40mph (guessing the speed of course), then dropping under ~20 mph.

Replacing a dead alternator, now the battery makes sense as the alternator charges the battery while the vehicle is running.

Do you still have a CEL for the o2 sensors? It is quite possible that one of them went out. Are you getting a CEL for the upstream or downstream (before or after cat) o2 sensor?

 

I changed to Speed Sensor and both O2 sensors last night. I was still getting the CEL, reset the CEL and it came right back on with the same results I was getting as well as a new code 1298. Looked it up and it was a fault code. I checked the fuses and found #15 on Interior panel was blown (speed sensor/alt) changed the fuse and reset the codes and everything is working as it should. So now that I have change the Alt/Speed Sensor/2-o2 sensors, I guess I will check all fuses next time.

 

any way to test a speed sensor?

 

Drive the car. If the speed shows on the dash, you know everything is working. Google how to test for resistance on it and what you should see when testing with a multimeter

 

I have a similar issue.speedo doeant work at all.altqntor wont charge batter (new battery),wont rev past 4200 rpm and cooling fans wont qork properly causing over heqting.please help

P.s
Can figure out how to make my own post

 

Fuse 15 problem:

* 1996-2000 model
* Speedometer doesn't work
* Alternator charges poorly or not at all; headlights flicker due to varying voltage.
* CEL on; codes for both O2 sensor heaters and other stuff.

Very common, a known bug in those years especially the first couple of years.