Instrument circuit issue

[jerrysdustydog]

Well of course another issue. Guages do not work and the fuse is blown to the "instrument" circuit. Checked the circuit and it has a 4 Ohm short. Took the shifter out and seat to get my big ass under the dash to try and find the problem. This is the reason I removed the dash and checked out as much as I could while doing the resto, but oh well. My question is where does the circuit first appear? I've taken almost everything loose except for the round plug to the instrument cluster. What can I check? I did use the electronic ignition set up and used the harness for the upgrade from Year one if that matters. Lights work and ammeter does as well, but no water temp, ect. Don't know exactly what the "instrument" circuit feeds. I do have a '68 manual, but am now cross-eyed from looking at the prints. Any help?

 

[Basketcase]

took the dash out...did you pull the instrument cluster, or the entire dash assembly? either way, look for a pinched wire. If you pulled the dash assembly, check the wires that go behind the driver's kick panel, good place for a pinched wire. If you pull the main wire plug from the cluster, be gentle, those pins can bend or break. check the wires for the amps gauge, make sure they are not touching each other, anything metal. good luck.

 

[george68hemirr]

YOU COULD ALSO LOOK AT THIS

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

 

[jerrysdustydog]

Thanks guys, but my problem is from the fuse to the dimmer switch. According to the print I have the feed from the fuse box (instrument circuit) is a tan wire that connects directly to the dimmer switch in the dash, on the center post. There is a tan wire on that post, but it has no continuity with the fuse box. As I said earlier, the circuit has a 4 ohm short, and the tan wire on the dimmer switch has infinite resistance to ground. Looks like someone jacked with this connection in the past and did some soldering across the lugs, so I'm guessing I'm on the right track. Dig a little deeper into it next weekend. I may have to run a new fused feed to this switch point and see what happens. Problem may be in the harness, and I'm not pulling the dash out (windshield as well) again.

 

[Basketcase]

wonder if the switch itself went bad. I assume you mean the dimmer wheel on the switch panel and not the high beam headlight switch on the floor.

 

[jerrysdustydog]

Yeah, your right about the dimmer wheel, that's where my book shows the "instrument fuse circuit" to show up first on the center position of the 3. Looks like the previous owner placed a jumper between the center and lower positions on the dimmer switch itself, soldering a jumper there, so I assume he had issues with the switch. I checked resistance between the center position where the feed should show up, and infinite resistance. So it's open somewhere in the harness, and shorted on the feed side. Oh well, I did find the problem within the cluster (temp gauge was bad and replaced it) and now the gauge shows hot instantly, and found the lead incorrect to the fuel gauge and corrected it, but I know the tank has less than 1/4 tank, but fuel gauge shows 3/4. Yeah, more work to be done.