temp

[Lyndon S.]

On my 71 LS-5 the temperature gauge is working some times and then it will drop to zero, do you think it is the sending unit? Is that temp sending unit still available from GM?

[William C.]

Re: temp

more likely a loss of electrical connection between the sender and the wire connected to it.

[Joe L.]

Re: temp

Kelly------

My guess would be a loose and intermittent connection somewhere, either at the sender or the gauge. It's also possible it's a grounding problem, especially if you've used any sort of sealer on the temp sender threads.

A sender is still available from GM. However, it has been widely reported that this sender is not calibrated properly for the old gauges. So, if you use it, you might not get an accurate reading.

[Lyndon S.]

Re: temp

The connections feel tight on the sending unit, what would be the solution ?

[Jack H.]

Re: temp

Understanding how the temp gauge works might help your diagnosis...

There's a pointer needle with two opposing electro-magnets. One magnet pulls the needle toward the cold side of the dial. The other magnet pulls the needle toward the hot side of the dial. The temp sender is a variable resistor that changes the current flow through the magnet pulling the needle toward the hot side.

If you have 'funnies' in the wiring from the gauge to the temp sender, you'll get needle pointer inaccuracy. Open circuit= cold readings and short circuit= hot readings.

BUT, you can get the SAME symptoms with wiring fault problems in the gauge itself. A bad ground between the gauge and its mounting in the dash cluster or intermittent connections inside the gauge and the two electro magnets can give the same symptoms.

So, you start by verifying the integrity of the wiring from the gauge to the temp sender and when that's complete, you turn to the gauge itself and its installation in the dash. Don't concentrate on one side of the system components at the exclusion of others!

[Lyndon S.]

Re: temp

When I drive the car and it warms up the gauge will show a reading, then say 30 min miles the gauge will drop to zero. It might come up an then it might not.

kelly

[Duke W.]

Re: temp

The temp sender/gage circuit also likely goes through a body connector at the cowl. All the pins/recetacles on this connector should also be checked once you remove it.

In any event, the problem is likely an intermittent open circuit or open ground at some point in the circuit. See your CSM wiring diagram and check all the circuit connectors and associated grounds.

Duke