Last yr I had the fuel/temp conundrum part 1. Now, nearly a yr later it's regrettably time for part 2.

I had my F&T gauges working for nearly a yr until recently. Right before they died the gauge needles would jump to the right (towards the full/high side and then settle back to where they should be), and this continued for a couple of months. I know now that that was a sign of a bad or failing Voltage limiter, I didn't know this at the time. Finally a few weeks ago the F/T gauge needles move to where they should be when I cranked up. Only this time they slowly retreated to left ( towards empty/low) and finally bottomed out. They are both no longer responding at all. It was at this time that I learned that all this was due to a bad voltage limiter...my gauges were trying to tell me this only I didn't know it.

I went and ordered a new VL (voltage limiter) a good one from Dash-Worx. Before I installed the new VL they wanted me to double check and make sure I have the proper amp fuses in the proper slots. Upon checking, I discovered that in 2 slots I'm supposed to have 5amp fuses, but I found a 20 and a 30 amp fuse in those slots ( unbeknown-st to me they were put there by the prior owner) So I changed them out and hoped that mistake didn't cause more damage when my old VL died on me. After putting in the right fuses, I finally installed the new VL, but my gauges did not respond...and in fact the new VL (which has a LED light to show it's functioning) was not flashing.

Which brings me here for what I hope will be some answers...

HERE's WHAT I'VE CHECKED:
1.fuses- they all test good
2. The actual F/T gauges themselves- I was afraid they may have been fried, so I took a 9v battery and tested them independently and they both worked fine. Tthe needles moved so they're good
3. The new voltage limiter- The new limiter has a test you can do to see if it works. I simply hooked 12v to it grounded it and its little LED came on and then flashed, which is what it's supposed to do...so it's good.
4. The 5 pins on the printed circuit board nearest the drivers door & the wiring harness that goes over the pins- I took my light probe and first tested the middle pin which corresponds w/ the black voltage limiter wire, and the probe lit up like a champ. That same pin contacts the circuit board and runs to the +12v slot that the VL plugs into, so I thought I touch down inside that slot to see if I get a light, but I didn't. However when I touched this spot last yr it also did not light, at least I think it didn't. If touching inside that slot should cause my probe to light then maybe that my problem...but I don't think it's supposed to. I probed the other pins they all worked, all but the pins that correspond w/ the Fuel & Temp wires.
5. Grounding at the F/T sending units- In the past when I disconnected the sender wires for both the fuel & temp gauges, and grounded them out to a good ground, it would make the gauges race to the right ( towards full/high side) Now when I did the same test neither gauge needle would budge at all. Remember I've tested my gauges they are not fried, they're good.
6. Sending unit in the fuel tank- Tested it w/ ohms meter and it's worked great I have half a tank and I got about a half tank reading. I'm sure the temp sender is fine too.

..So that's what I know. I feel at this point that either my F/T wiring is fried somewhere from the sending points to the dash. Or that I'm simply not grounded good at the dash anymore. I'm not sure if that's it because everything else, light etc.. on the dash is working fine.

BTW: the folks that sent me the new VL told me to test my limiter to see if maybe it was faulty. They told me to clip one end of a wire to the grounding spade ( it goes over the top of the limiter) and run it to a screw or a good ground under the dash. Basically run a single ground to the limiter and turn the car ON. They said if it's working the LED should come on and flash. I did do this test but the LED never came on. They also told me I could test it outside the car using any 12v power source. Like I wrote above when I tested the VL this way it worked fine.

THAT IS IT. I hope all this information will tell someone on this forum what my problem may be. At this point I'm not really sure what to try next. Thanks for any help anyone can give

Oh yeah I forgot to mention, my car is a 4 door- 1968 Dodge Dart 270

Have you been able to check the output of the new solid-state voltage limiter?

It sounds like you may have a broken or loose pin on the cluster, on the mating connector that feeds 12V to the back of the cluster, or a broken, cracked, or burned trace on the back of the instrument cluster. A loose pin on the board is not uncommon and can be very annoying, as it can come and go and may only show up when stressed a little by the plug.

The good news is that it is fairly easy to fix the cluster once it's out of the car with a little careful soldering.

No I have not - the folks at Dash-Worx said that if their limiter's red LED light comes on and then flashes then it IS working...they explained that's all I need to see to know it works.
It's just that the LED light isn't doing anything when I plug it into my circuit board even w/ a ground wire running directly to it. I've explained this to Dash-Worx and they believe that if the limiter is working (flashing) outside of the car when testing it to a 12v battery, but is not working plugged into the car, then it must not be getting any power while plugged in the circuit board in the car.

On a separate point. If my fuel & temp gauges have tested good (and they have) and I go the sending units of either gauge, unplug the sending wires and ground those wires to the cars body (on a good ground) and the gauge needle for whichever gauge sending wire I'm grounding does not move to the right...toward full/high side - then that surely means I have a problem in the wiring somewhere between one end of the sending wire up/back to the dash. Does this sound correct?

Yup I already repaired this circuit board last year. I jumped a break in the copper circuit that actually runs power to the VL. That repair worked last yr but I found this companyhttp://www.premiumdashdecals.com/dash_c ... boards.htm..and since there's a potential of my repairs failing (and is probably failed) or whatever, I'm ordering theirs. With a new board I can eliminate that as an issue.

Scott, it sounds like you're on the right track with the circuit board.
Please give us an update when you have it all back together with the new board.

Well, I got my new circuit board in today and it sure was purdy. I had already bought a new solid state Voltage Limiter but I couldn't get any power to it..hence the new board. Anyway, I pulled out the instrument panel and made the swap. As it turns out, that new circuit board is all I needed to straighten everything out. When I plugged in my new VL it powered on and the Fuel gauge moved to it's correct position. I'll need to get the engine warm before I know about the Temp gauge.

Apparently when my old VL failed, (and having the wrong size fuses), led to my circuit boards connection to the VL to get fried somewhere. I'm glad my wiring and gauges are all fine (so far), and that there's a group out there making these new VL and printed circuit boards, 'cause boy they helped me for sure. Sure beats scrounging in junk yards or eBay for old instrument clusters.

That's the update. Thanks for all the helpful tips and suggestions.

That's great to hear, Dave. Sounds like you're back in business and we've found another good vendor.

It's good to see that they also sell boards for the 64 Darts. $130 each seems like a lot, but since my high-beam indicator and several dash lights work intermittently, the board is probably what's wrong. I've removed the board and cleaned the connections on the sockets and board at least twice and it's still acting up.

I really appreciate the update, and congratulations!