NEED HELP TROUBLESHOOTING FUEL GAUGE

[92accordowner]

Hi,

The fuel gauge in my '92 accord decided to stop working the other day. Kind of a long story but you will need this info to help me determine the next step. It's a DX sedan, MT, no ABS or CC, with A/C.

I think this may be related to a problem I had with the open-door/brake light indicator, which started acting strange about a year ago and now just stays fully lit all the time.

I took out all the seats to detail the interior well, and everything in the back looked fine when I did that (no signs of water intrusion, wire damage, etc.)

I took apart the center console and dash plastic just enough to remove the instrument cluster to inspect it. Stereo connections and cig lighter power are left unplugged, everything else still connected.

I opened up the cluster and there seems to be a burnt area on the back (green side) of the PCB, right near that door-open indicator. I suspected this was the cause of my problem so I ordered a replacement from a junk yard for $60 (annoying to have that thing lit up all the time, and rather fix the feature than delete it... should have just pulled the bulbs, I guess).

When I put the cluster back in temporarily to drive the car (because my stupid Saab broke down!) the fuel gauge was no longer working.

I figured I might have caused this by messing with the cluster, but I didn't really do anything to it. Anyways, when the new one arrived (w/ warranty and guaranteed working) I immediately opened it up and it had an almost IDENTICAL area of 'damage' where it looked like there was a short and some burning on the PCB.

I installed the new cluster and everything worked perfectly, including the door-open indicators, EXCEPT the fuel gauge! At this point I immediately suspected a failed sending unit, which is a rare thing to fail.

I looked up how to troubleshoot the sending unit in some Honda service manual. Voltage going to it was about 6V like it should be, ground was good, and voltage coming back was something like 3V. Jumped that return signal to ground (which should have made the gauge needle begin to climb, according to the manual) and nothing happened. Manual says to replace the gauge.

Thinking I might have gotten struck by lightening and ended up with another bad cluster, I ordered a second replacement but it was the wrong version (not the NS version, but all the connections were the same. I hooked it up anyway and the fuel gauge didn't work, but not sure if it should have or not, being the wrong version). So I ordered ANOTHER one, making sure to get the NS version, but two of the 3 connectors were different, and it was damaged in shipping, so that one didn't really help me neither.

Still thinking it's unlikely that it's the cluster, and failing to find the right one for my specific car, I turned my attention elsewhere.

I pulled the sending unit from the gas tank and checked it's resistance... float from top to bottom, resistance changed from 0 to 100 ohm like it should. Reinstalled it.

Ordered a new, genuine sending unit for the sake of troubleshooting, plugged it in, moved float around, no movement on gauge.

So I'm stumped. Seems like I have a good gauge/cluster now, because it was guaranteed working and it fixed the door sensor issue, and a good sending unit in the gas tank (and yes, there's lots of gas in the tank, lol). But there is still that apparent damage on the PCB. Keep in mind, however, that my old one had basically identical damage on it when I pulled it, and right up until I pulled it, the fuel gauge was working just fine. Hence my confusion.

What else could be wrong? Maybe 12V is shorting to the gauge somehow and making it always read empty? Does that even make sense?

Is there more I can do to troubleshoot electrical? Jumper out on certain pins and check voltage at the cluster, for example? I can't find a schematic for it.

By the way, I did take a close look at the connectors and pins on the clusters and nothing seems pushed or damaged, should all be connecting well.

Please help me determine what a good next step would be. I am also considering installing an aftermarket gauge since the sending unit is 0-100 ohm and working, and I'm getting tired of messing with it.

Thanks!

[92accordowner]

Follow up question... it's very hard to find a cluster exactly like my original. Even the second one I got that fixed the door sensor issue is not an EXACT match.

My question is, should that matter for the sake of troubleshooting this fuel gauge if I use an identical one or not, because there are many cheap ones I can get and try that are made for AT cars. If all three connectors are the same, are everything else in the cluster works fine, shouldn't the fuel gauge also be working?

Thanks.