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temp light
1966 c20 with idiot lights, should the red light come on when you turn the key on or just when the engine is too hot? The green one works as it should. Thanks Lowell
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Bumping this up. I have the same question and have not found my answer yet in searching. Mine does not come on when I turn on the ignition, and currently my green does not come on at all. I have replaced the bulbs and no change, so looking for some info.
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Its been some time since I had warning lights, but I remember them both coming on and only a green light while the engine is cold.
Mike.....Id replace you temp sending unit since you've already replaced the bulbs. Also make sure the wire is connected to the sender. Its possible that someone unplugged it at some point. |
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no problem. the sending unit is an easy fix...takes 2-3min
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You might want to check out THIS thread for a complete tutorial on the temp light circuits. I suspect that many a sender has been swapped out for want of a good electrical connection somewhere along the way.
Sounds like you have got your problem solved and I know that's a good feeling. ...ned. |
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With the connector partially plugged onto the temp sensor, if I clip my test lead to ground each blade, the lights will come on. So it looks like the connections inside the plug are good too, just need the new sensor now. |
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The red light should come on when the key is turned to start position. The green comes on when the key is in run position & goes out when the coolant starts to warm up. Its a good idea to replace the sending unit everytime you get a truck with this system. There is no easy way to test the hot side.
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So, to answer your question directly, your problem might be too much coffee. :mm: ...ned. |
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hahahaha
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This thread got my attention because neither my hot nor cold light has ever worked in my '64 truck. I installed a new sender unit when I replaced my water pump because I noticed that one of the blades on the old sender unit was broken off. But still have never got the lights to come on even though I have tested both lamps, and they are good.
Based on what I read here, I pulled the L-shaped connector out a bit (but still connected to the sender) and attached a ground wire to one terminal and I had a Cold light for the first time! I then moved it to the other termindal and the Hot light was lit. I also used my test probe from the positive battery terminal to the brass body af the sender unit, and it lit. So I assume that my sender is grounded (was afraid I might have used too much tread sealant). But I still have no lights if I don't ground the terminals... So I guess I don't understand where my problem lies... Is my L-shaped connector bad? I tried scraping the female connections with a small screwdriver and reconnecting it, but that did nothing. I assume the connections are good because both lights work when I ground each terminal. Any help would sure be appreciated. It would seem that I am close, but no cigar. :-) |
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ohm out the cold side - terminal to ground. if no continuity then sender is either bad or the wrong one
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Thanks for the test procedure cg285. It looks like I have a bad sender unit. I was beginning to suspect that yesterday after I found that the lights did work when grounded. I bought this unit from Classic Parts along with the rest of the colling system parts, but guess that I got a bad one. My local NAPA store will have one for me today by 2:00 though.
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Put the new temp sender in without losing a drop of coolant (drained a gallon out of the radiator to lower the water level) and immediately had a Cold light when I turn the key on. That's a first since I've had the truck! I'm sure I'll see the Hot light come on when I crank it, but letting the tread sealant harden before refilling and cranking it. Thanks to this thread, I now understand how this thing works!
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Glad you got it working!!!
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I am too! :lol: After new brakes, the first thing I did was rebuild the cooling system, but never knew that my new send wa bad right out of the box. But I guess better that than hacked up wiring.
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Sounds great. I am hoping FedEx is not too late showing up at my house tomorrow so I can get mine installed. The truck was originally my grandfather's, and I have had it for the past 13 years. In the time I have owned it the cold light has never functioned properly.
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Having your grandfather's truck must be great Mike! I hope your sender comes in time to install it. A 15/16" socket or wrench and some thread sealant ought to be all you need. I drained a gallon from the radiator, and didn't see a drop of water when I removed the sending unit.
Let us know how it goes. My cold light came on and stayed on until the truck warmed up, then it flickered out. I don't think I saw the hot light though when I cranked it though. I'll be curious to know if you do. |
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Anyone have a source for the sender? Mine's melted where the harness plugs in.
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Yeah, I got my sender from NAPA yesterday. They didn't have it in stock in the morning, but had it for me by 2:00 in the afternoon. Comes with a 3 year warranty too. Not sure if you have NAPA in Canada though. Rock Auto also has them. I got my first one from Classic Parts last summer, and apparently got a bad one.
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