temp gauge

[Clavo106]

I have no idea how this thread got so complex. with so much insight. hope the best of luck

[VetteVet]

Originally Posted by moon

SO, when I touch my properly grounded test light to the #3 purple feed pin on the connector, the test light should go on.... right? And if so; in what ignition key position ---> ignition on? ... accessory on?... both?.. with engine running on or off?

Both my temp gauge (new) & gas (original) don't work & appear to be "dead" & I've been messing with this for toooo long....

I believe it only powers the fuel and temp gauge in the "run" position. The accessory position is powered by the red battery wire when the switch is in the run and ACC position, but the RUN position is only powered in the IGN run position.

Originally Posted by moon

Thank you for your help!

I checked the plug terminal (disconnected from the panel) with my test light & do NOT get power at the #3 pin. But I DO get power at the cluster pin, when the headlight switch is pulled on.

I'm having difficulty following the schematics: I'm not seeing the "junction" you mentioned where the pink wire & two others run to. Also a bit confused with pink wire vs purple wire.

See my post with the diagram in it and read the top of the diagram I say that the pink wire is the fifth one down on the ignition switch. Follow this wire into the diagram and you'll see where the junction is of the three pink wires.
The cluster diagram I posted in post 11 has different colored lines indicating the paths of the cluster pin wires. You'll notice I said Purple LINE not purple wire. As you know these are all copper strips. Go over the posts I made carefully and you should be able to decipher information. As always ask any questions you need to clarify anything.

I have a '70 C10 CST. The #3 wire in my terminal is pink(ish.) All the wires coming from the ignition switch are bundled/taped together and lead up, over & down to the top of my fuse box, appearing to run down behind it. The pink wire coming out of the connector on the firewall side of the fuse box runs to the starter.

I believe you are referring to the starter solenoid wire, which is a 12 gauge purple wire, not pink. In time it may look pink, but it is larger than the n0. 3 feed wire. The coil resistance wire that goes to the starter use to be an orange/ purple/ white, wire and it is the same gauge as the no.3 pink wire, so you might be seeing this.


If The pink wire powers the cluster lights (as it should) but is not powering the #3 pin, where should I look to find the break? Cluster feed fuse

Also: I don't know if this is related (doubtful?) but my altimeter reads backwards --> When the headlights are on without the engine running the needles leans right to "C." When I start the engine running, the needle leans left to "D" then after eventually returns to the center line.

It's obvious that you're flying upside down

Sorry I couldn't resist. I think you mean Ammeter. This is almost always caused by reverse wiring on the gauge. Check the no. 1 and 12 wires on the cluster plug and you may have to reverse them. These wires are both positive
so do not ground anything. The no. 12 wire comes from the battery and the no.1 wire comes from the alternator battery junction. I can post a diagram in another post if you wish.

Here are some shots of what I'm dealing with:

IMG_0053 by moon, on Flickr

IMG_0051 by moon, on Flickr

IMG_0049 by moon, on Flickr

Originally Posted by Phildeez

I'm in need of a little help on the subject too. My gauge only rises to the second line of the cold zone and fluctuates down and back up to the same point. I've tested my gauge by grounding it and it goes to hot. I've got a reading of 333 ohms after a it is warm and the gauge is still just off the first cold line. According to a resistance/temp chart it was right around 175-180 degrees. Any help would be appreciated.
Posted via Mobile Device

See post 20 you're running too much resistance in the sender for the gauge. This may be caused by using sealant or Teflon tape on the sender threads that is grounding resistant., or you may just have the wrong sender.

[Phildeez]

Thanks for your reply. I thought that too about the thread sealant. But my reading of 333ohms tells me the sender is working. Right? The cart temp was right in line too. Please let me know if I'm missing something here.
Posted via Mobile Device

[VetteVet]

Originally Posted by Phildeez

Thanks for your reply. I thought that too about the thread sealant. But my reading of 333ohms tells me the sender is working. Right? The cart temp was right in line too. Please let me know if I'm missing something here.
Posted via Mobile Device

As you can see from the previous posters, the resistance of the sender affects the gauge reading thusly, the lower the sender resistance the higher the temperature reading. This is demonstrated by grounding the sender wire for a zero resistance to the gauge, and having a full hot reading on the gauge.

Have a look at post 20 in this thread.

[midnight rambler]

I to had issues with the temp gauge on my 74 I ended up buying the correct sender unit and a new wire from lectric limited. now if I have time to get it installed.

[Phildeez]

Does anyone know what the ohms reading of the correct sender to have a stock gauge read in the 190 degrees range?
Posted via Mobile Device

[moon]

Does anyone know what the ohms reading of the correct sender to have a stock gauge read in the 190 degrees range?

Here is a chart I found on this site. Hope it helps.

[moon]

See my post with the diagram in it and read the top of the diagram I say that the pink wire is the fifth one down on the ignition switch. Follow this wire into the diagram and you'll see where the junction is of the three pink wires.
The cluster diagram I posted in post 11 has different colored lines indicating the paths of the cluster pin wires. You'll notice I said Purple LINE not purple wire. As you know these are all copper strips. Go over the posts I made carefully and you should be able to decipher information. As always ask any questions you need to clarify anything.

The wires in my fuse block connector aren't the same as what is pictured in the diagram. I've got 6 wires & the diagram shows 7 wires + the colors are not the same. I installed an H&M harness and now before I go any further I'm going to confirm I have the correct harness. After that I'll start a separate thread since my issue(s) are not the same as others posting here. THANKS again for your assistance!

[Phildeez]

Originally Posted by moon

Here is a chart I found on this site. Hope it helps.

Hey, thanks moon. That's the chart I found and was referring to in my original post. Which is why I'm still questioning my sender being bad. I get 333ohms after a nice little drive. So according to the chart the sender is telling the gauge to "display" somewhere in the 180 degrees F area. Thanks guys for your patience haha
Posted via Mobile Device

[ol'blu72]

Phil, where are you taking your resistance measurement? If from the sender there could be resistance in the wiring to the gauge. Either way look for more resistance from where you are taking your reading and to the gauge itself. If you are taking it from the gauge then maybe it is time for a new one.

[Phildeez]

I'm taking it from the nail head on the sender to ground. You bring up a great point about the wire adding resistance. Gives me something else to look into. Thank you!