i'm troubleshooting my oil temp in the combo gauge that doesn't give a temp reading. when i turn on the ignition, i see the needle jump to the cold line but no deflection on a warmed up engine. i measured the resistance of a spare taco i had on the bench and got about 1300 ohms and the one on the engine in the car doesn't give any resistance so i've deduced it's bad and will swap it next oil change.

do taco plate senders ever go bad?

After 35 years, everything has the potential to go bad. However, I would look at the wiring first. There's a better chance the wiring has gone bad/gotten shorted than the actual sender going bad.

Eric Read

I agree.

There are two connectors that could be dirty enough after 35 years to give false/no readings.

One is under the computer/battery tray. Its where the wire comes up into the engine bay and plugs into the wiring harness. Good place for corrosion.

The second is under the tunnel carpet, passenger side just near the shifter. Again...good place to get wet over the years.

The nice part is these two connectors give you a built in place to test the sender as you mover towards the gauge.

rich

i traced continuity from the gauge to the taco sender and i think the wire is OK. i disconnected the wire from the gauge and the sender to avoid error. i tried to measure the resistance of the sender in the taco plate and got a confused reading on the one mounted on the engine. i got a steady reading of the resistance on another sender not mounted. i was just wondering if anyone had encountered a bad sender as that is what i suspect i have and i have never heard of a bad sender.