Gas Gauge causing short? 1966 Barracuda

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Steve Clason

Steve Clason

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So I've been having a terrible time getting dash lights to work. I replaced the circuit boards and the lights still don't work. I did have them working a couple years ago. I've tried the fuse but it blows as soon as the light switch is on.

So today I pulled the dash to my bench and started chasing the circuits with my ohmmeter.

I found that when the gas gauge was connect the entire left circuit board was shorted out. Pick any two terminals or spots on the board and the circuit was complete. So I wondered if this was somehow normal.

If not normal then I'll be looking for a new gauge (rebuilt obviously).
If normal I guess there must be a wire I've not traced yet.
(By the way I can take the dash out in about 5 minutes or less since I've had it out to try and figure this out so often)


Any suggestions and ideas are welcome.
 
You are somehow leading yourself down the wrong road You are likely reading an ohmeter, and reading a backfeed condition.

The "path" for the fuel / temp gauge is ---power pin on the connector---board trace--through IVR--common trace to the temp and fuel gauge---through the gauges---to board trace--back to pins on the connector for fuel or temp respectively. The IVR by the way is grounded.


By the way, while you have it out, make certain the board pins are tight, and consider soldering them from the pins to the board traces anyway.
 
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You say you "tried the fuse" what fuse are you talking about exactly? Here is how dash lights work:

The light switch has TWO power sources. "ONLY" the headlights is not fused and comes from the ammeter circuit. The headlights circuit has a breaker in/ on the light switch

The tail/ park and dash lamps are supplied from the tail fuse circuit in the fuse panel. That power goes through the dash light dimmer and comes out on tan which goes BACK TO the fuse panel to the INST fuse. Through that fuse and off to all dash dimmer controlled lighting on ORANGE wiring.
 
Some things to try and I hope you have the battery disconnected. You DO have the cluster out, right? Safely jumper the ammeter wires together and power up the system and see if the fuse blows with the cluster out of the car. If not then the short is likely indeed in the cluster. You should be able to easily find that. I assume you have the 3 terminal fuel gauge IE "Ralley" cluster which means the IVR is inside the fuel gauge
 
The fuse is the instrument cluster fuse. That’s what keep blowing. Battery disconnected for sure. Will try the suggestions soon. Had to put cluster back in for a cruise tonight. Hopefully will get back to this Monday. Really hope Friday but wife had some plans
 
The only thing the INST fuse does is fuse the orange dimmer controlled lighting wires. The problem MAY NOT be in your cluster at all. Look around for ALL dimmer controlled lamps and this varies with year/ model. Dash cluster illumination lamps, of course, radio lamp. The shift quadrant. There are others "depending." I believe the ash tray lamp is dimmer controlled but I'd have to look it up
 
67Dart273 said:
The only thing the INST fuse does is fuse the orange dimmer controlled lighting wires. The problem MAY NOT be in your cluster at all. Look around for ALL dimmer controlled lamps and this varies with year/ model. Dash cluster illumination lamps, of course, radio lamp. The shift quadrant. There are others "depending." I believe the ash tray lamp is dimmer controlled but I'd have to look it up
Click to expand...

will do. Had a problem with pillar light but now I wonder about the under dash being the problem
 
Pillar light? You mean as in dome/ courtesy? If the INST fuse is blowing, again, the only load on that circuit is the orange wires and these are the lighting controlled by the dash dimmer control

You have a console? Console shift quadrant?
 
No console. Just one under dash courtesy light and the 2 courtesy lights in the rear seat area. Pillar lights are what a couple molar friends called them.
 
Steve Clason said:
No console. Just one under dash courtesy light and the 2 courtesy lights in the rear seat area. Pillar lights are what a couple molar friends called them.
Click to expand...
I don't know if you are confused or just made the comment. I'm not referring to courtesy lamps. You were referring to the INST fuse blowing. That fuse ONLY fuses the dash lights which are fed from the headlight "dash dimmer" control. Also, that INST fuse, which is quite small, is fed from the tail light circuit power source. Re-read the earlier post.
 
I would "step back" a bit. Make a chart (from the manual) what fuses feed what. Remove ones that are not involved temporarily to get them out of "the running." the tail/ brake lamp fuse feeds dome/ courtesy, dash lamps, tail and stop lamps.

After the dash lamp power goes through the dash dimmer THEN it ALSO goes through the smaller INST fuse. That is blowing? That is a clue
 
67Dart273 said:
I would "step back" a bit. Make a chart (from the manual) what fuses feed what. Remove ones that are not involved temporarily to get them out of "the running." the tail/ brake lamp fuse feeds dome/ courtesy, dash lamps, tail and stop lamps.

After the dash lamp power goes through the dash dimmer THEN it ALSO goes through the smaller INST fuse. That is blowing? That is a clue
Click to expand...

Yes the little inst fuse is what is blowing. Everything else electrical works fine.
 
Sounds like you may have a couple of problems.....and possibly related ones. How about a good photo of the back of your instrument cluster. Maybe we can see something you missed.
 
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