ONLY my amp gauge works :P help!

[The4ork]

got the car fired up and driving for the first time since i bought it. but there isnt a single working gauge except the amp gauge. LOL

the speedo looks like it just needs the cable hooked up. its hooked to the gauge but the PO swapped in a 4spd manual so maybe its not tied to the trans yet.

a tach would be really nice to have!
so would a h20 temp gauge. but as it turns out i also dont have a sender for this installed! does anyone have a link to where i can buy a new one?
oil pressure is inop
fuel gauge is inop

almost seems like none of the gauges are powered up.

is there a diagram on how each one is wired? maybe the ground isnt connected or needs cleaning? maybe there is a relay that controls the power that is stuck off?
also the lights dont work in the gauges either.

looked under the dash to try and trace some wires....  lots of splices over the years.

oh yeah its a 72 cuda rally

[Grec]

Oil, temp and gas are all on the same power circuit.

Basically 12v goes into a voltage limiter mounted to the back of the gauge cluster and then the stepped down current goes to these gauges. Quite possible that the voltage limiter went bad. It's a known weak link.

You should be able to find a temp sensor just about anywhere. (oil sending unit, too)

[ShelbyDogg]

a tach would be really nice to have!
so would a h20 temp gauge. but as it turns out i also dont have a sender for this installed! does anyone have a link to where i can buy a new one?
oil pressure is inop
fuel gauge is inop

From Rock Auto website:
1972 DODGE CHALLENGER 5.2L 318cid V8
Electrical-Switch & Relay : Temperature SwitchRelated Parts 
ORIGINAL ENGINE MANAGEMENT Part # 8210 {#3173363, 3177594, 3179953, C3AZ10884B, C5EH10884B, D1FZ10884B, GTR114} (Only 9 Remaining)
w/ Gauge   $3.59

If your dash was a non-rallye, you have to add a wire from the coil negative to the tach.

If your tach and gauges are not working, and you had a rallye cluster originally, it sounds like you aren't getting any power to the dash or the limiter is bad like Gec mentioned, but your tach would work.