Console temp gauge problem

[EasyJoe]

Hi guys and gals,
I've searched this and Team Camaro's forum, used all the suggestions and still can't figure this one out.
I installed console gauges in my 69 with a 350. All the gauges work. However the temp gauge only works correctly when the car begins to warm. No matter where the needle is when I first turn the key the gauge jumps to hot. When the car warms it will drop and rise to the correct spot. I have an after market gauge to see the actual temp so I know it's correct. As I drive around it will jump to hot and a little while later it jumps back to the correct reading. Again the after market gauge is reading a constant 185 to 200 while this is going on. When I turn the car off the gauge seems to stay where the 180 area is even after it cools. But, as soon as I turn the key to start it again the process starts over (over to hot until warm, etc.)
Any one got any ideas?
Thanks, Joe

[Everett#2390]

What have you done in troubleshooting the problem?
I suggest taking a singular 200 to 400 ohm resistor, any value in between, and attach one lead to engine ground, the other lead to the green wire going to the gauge without the sensor and view the indication.
If rock solid indication, then bad sensor.
If the indication still varies, move resistor to the gauge itself and disconnect the green wire and connect the resistor.
If gauge indication is solid, check the green wire for chaffing to body ground and firewall connector for good connection.
If indication still varies, bad gauge, or bad ground on gauge itself, or intermittent power to gauge.
The problem may not be power as you did not say any problems with the other gauges as each gauge power comes from one wire in the console harness.
Could be a bad crimp in the power wire for the gauge, depends upon how the harness was made.
Unless I'm missing something here.

[x66 714]

When you installed the gauges, did you change the temp sender to one for gauges or do you still have the one for the light?
...Joe

[Kelley W King]

make you have a Delco sending unit also. The parts house units give trouble plus the only thing correct about them is they fit in the hole.

[EasyJoe]

Never used the temp light hook up, had an after market temp gauge.  I bought the correct temp sender for gauge with the harness from AAW. All the parts are new but the sender is not Delco. To troubleshoot I've rechecked all the wire and checked the gauge with and without the green wire grounded. All is well there. I used an ohm meter on the sending unit, looks ok. I haven't tried the ohm resistor yet. Guess that's the next step when I get time.
There was a small amount of plumbers putty on the plug I removed from the intake. I didn't clean it out. However I ran an alligator clip from ground and around the senders body. I would think that would have grounded it enough.

[69pace]

Never used the temp light hook up, had an after market temp gauge.  I bought the correct temp sender for gauge with the harness from AAW. All the parts are new but the sender is not Delco. To troubleshoot I've rechecked all the wire and checked the gauge with and without the green wire grounded. All is well there. I used an ohm meter on the sending unit, looks ok. I haven't tried the ohm resistor yet. Guess that's the next step when I get time.
There was a small amount of plumbers putty on the plug I removed from the intake. I didn't clean it out. However I ran an alligator clip from ground and around the senders body. I would think that would have grounded it enough.

Okay so have you bench tested the Ohms output from the unit under various engine warm up periods from cold to operating temp? If the sender is working you will get various ranges from the sender and those also differ by the manufacturer. There is a chart of those over at TC. Here is the post: http://www.camaros.net/forums/showpost.php?p=1607532&postcount=6 Full thread here: http://www.camaros.net/forums/showthread.php?t=186128

Also what gauges are you using now - Original AC Delco, NOS AC Delco, or Reproductions? 

The reproductions are made by two firms with different guts. Classic Headquarters makes the closest to factory reproduction available. These require, just as the original AC Delco gauges did, an external resistor on both the fuel and the temp gauges. The resistors are not interchangeable between the two gauges either. Classic HQ uses a modern ceramic unit that bolts to the poles on the rear of the gauge. These modern resistors can be used on original factory Delco units. OER reproduction gauges are internally resisted and do not need an external unit and will read wrong if one is attached. Original AC Delco gauges used a hand wound resistor card and if the thin wire has broken will not work. These can be restored as long as the Mylar card is not cracked or other wise damaged. 

[396 SS/RS]

I know this is an old post and am hoping someone can lead me in the right direction to correct my issue. When I sold the car in 2001 everything worked. I recently bought it back from him and the temperature gauge and battery gauge are inoperative. 
I grounded the green wire to the sender and the gauge goes to HOT, open the ground and it returns to full COLD.
I replaced the sender with the correct AC/Delco sender, ensured continuity from the sender to the block but still no operation.

As far as the ammeter goes he had installed a one wire alternator, unplugged the external voltage regulator and left the small 2 wire unplugged at the alternator. I installed the correct alternator using the two wire plug and reconnected the external voltage regulator. but still have no indication.

Thanks in advance!

[396 SS/RS]

I know this is an old post and am hoping someone can lead me in the right direction to correct my issue. When I sold the car in 2001 everything worked. I recently bought it back from him and the temperature gauge and battery gauge are inoperative. 
I grounded the green wire to the sender and the gauge goes to HOT, open the ground and it returns to full COLD.
I replaced the sender with the correct AC/Delco sender, ensured continuity from the sender to the block but still no operation.

Just an update... Many people ask questions get suggestions but never follow up with what the problem was.

I resolved my issue from following suggestions on another forum. It was a ground gremlin, I found the screw mounting the horn relay to the radiator core support was loose. tightened it up and it's working now.

[David K]

Glad you found it. Because it makes perfect sense that a loose ground screw that is 7 feet away from the problem would cause this. Oy. Can we at least get a picture of this gremlin?