Hi - first post - I've read some posts about gauges not working at all, but I haven't run across one like my situation - I have a 1998 Civic LX Sedan (D16y7) and a couple of days back it seemed as though my temp gauge was running a little lower than usual - usually runs a little less than halfway between hot and cold, but now running at about 4 or 5 oclock (about 1/4 above cold).

As well, I thought that my fuel gauge suddenly seemed to show more fuel than I thought I had in the tank. Since I usually reset the trip odo at each fillup, I knew when I should be running out of gas fairly soon - so I threw a can of gas in the back and went for a drive. The low fuel light came on with the gauge reading about 1/4 tank left. So I filled it up at the next town and the gauge isn't quite showing full, but pretty close.

Checked/changed fuses - no change. It's like one of the sensors is slightly off, but not fully and it's affecting the other.

Anyone have any experience with this? Thought I'd throw a note out for some tips before I start digging in to the car.

Thanks - Grant

 

OK, I'll respond to my own message and tell you what I've found - I disconnected the single wire from the ECT sender unit and connected an ohmmeter between the ECT positive terminal and the yellow/green wire to the gauge - the readings were quite high at full temperature (162 ohms) and got larger as the coolant cooled down - last I looked, it was at about 220 ohms and rising.

Interesting though, with this connection in place, if I had the car running, I could not read the ohmmeter. Once I shut the car off, I could read it.

The other test I tried was to attach a lead to the yellow/green wire and ground it to the chassis - from what I read, I thought the temp gauge would increase towards H, but it did not move at all - in fact, it almost seemed that it sucked to the bottom as opposed to increasing - did I connect something wrong?

So, I'm leaning towards a faulty ECT sender unit. Any other suggestions? I haven't tested the fuel gauge yet - I don't want to have to pull things apart to get at the wiring just yet.

Any input or suggestions would be appreciated.

Cheers,
Grant

 

I guess I'll keep talking to myself......

So, I think I did the tests wrong - I dug around and found the page from the manual that I had seen earlier to make sure. One test was just plain wrong, while the other I just had a bad ground.

I redid the test of the ECT sending unit since I did this wrong the first time - I connected the ohmmeter to the terminal on the ECT and then to a good ground - when I started, it was reading about 320 ohms - that seems high considering the page from the manual indicated that 142 ohms would be right at a cool temp. Anyways when I ran the engine for awhile, the ohmmeter reading fell to about 72 ohms when the fan kicked in. Again, that seems a bit high.

When I retried the gauge test now that I got a good ground, I connected a lead from the yellow/green to ground - when I turned on the ignition, the gauge immediately jumped to H - had to shut it off quickly! So the gauge seems to be ok.

Anyways, I will continue with my thought that the ECT sender is faulty.

Again, any suggestions/comments are welcome.

Cheers,
G.