| Av68@reagan.com | -- 12-04-2024 @ 3:46 AM |
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1940 Ford deluxe coupe flathead 8Ba V8. 12V. I added a second temp sending unit ( passenger side) w/ the one top screw. In doing so, I changed the first sending unit (drivers side) to a unit with two posts. I didn’t use any pipe thread etc. I connected the passenger side to the drivers side with a crossover wire. Then I added a ground wire from the driver side to my fire wall and reconnected the original wire running back to the gauge. Now my temp gauge inside the car doesn’t operate with the car running. I noticed when I turn the ignition switch on, the gauge needle works, but when I turn the key to the on position, the needle/ gauge turns off. Any knowledge/wisdom would be grateful. This message was edited by Av68@reagan.com on 12-4-24 @ 3:48 AM
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| JayChicago | -- 12-04-2024 @ 8:40 AM |
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This is confusing. Seems like you installed the senders and wired it correctly, but couple things don't make sense. "Then I added a ground wire from the driver side to my fire wall" The driver side unit does not need a ground. It is simply an open/closed switch. Normally it just carries gauge's sender circuit thru that switch over to the other sender, which controls the gauge. If engine gets hot, switch opens, gauge needle goes to full-hot. But if the circuit was improperly grounded there, needle would probably go all the way down, gauge not working and maybe damaged. I would remove that added ground wire. "when I turn the ignition switch on, the gauge needle works, but when I turn the key to the on position, the needle/ gauge turns off." Turn the key to on position? What do you have for an ignition switch?
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| Av68@reagan.com | -- 12-04-2024 @ 1:37 PM |
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I added the ground wire from reading a past post (and probably misunderstanding what they were talking about) on this forum, not realizing that the temp switch already acted as a ground. Correct? Sounds like I didn’t need to do that? Let me back up to the beginning; I originally had a plug (no temp sending unit) on the passenger side of the motor and a temp sending unit ( stamped with a KS ) on the drivers side of the motor. This drivers side temp sending unit was then wired back to the temp gauge. The temp gauge in the car worked fine with this configuration. Thinking I could get a more accurate reading from both sides of the motor, I then removed the plug and the ‘KS’ sending unit to add what I explained in my first question. I have the stock ignition switch in my car (the steering lock/ignition switch with the on/off toggle switch).
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| 40 Coupe | -- 12-05-2024 @ 6:50 AM |
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No grounds needed. Wire from dash gauge goes to the two terminal unit. The second terminal on the two terminal unit is a jumper to the single terminal unit.
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| JayChicago | -- 12-05-2024 @ 10:41 AM |
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How did you connect the new ground wire to the switch/sender? Is it on one of the two terminals?
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| Av68@reagan.com | -- 12-05-2024 @ 11:29 AM |
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Thank you for your response. Yes, the wire (black) goes from my dash gauge ( which is part of the original dash cluster of gauges & speedo) to the temp sending unit, which is now a new two terminal sending unit. Then the second terminal has a jumper running to the single terminal on the passenger side of the engine. But now, the temp gauge on the dash runs backward. When I had just the one temp sending unit on drivers side and a plug on the other side, the gauge read in the correct direction. ???
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| Av68@reagan.com | -- 12-05-2024 @ 11:32 AM |
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Yes. On the two terminal sending unit ( on drivers side) , I have the black wire from the dashboard connected to one terminal and on the the second terminal, I ran a jumper wire to the new sending unit on the passenger side. I removed the grounding wire. But now my temp gauge at the dash reads backwards.
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| JayChicago | -- 12-05-2024 @ 12:42 PM |
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Good that grounding wire has been removed from the switch/sender, was providing a dead short to ground. Gauge now reading backwards?? Please describe what the gauge is doing.
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| Av68@reagan.com | -- 12-05-2024 @ 6:11 PM |
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All the other three gauges move from left to right when I turn the key to unlock the wheel and I flip the toggle switch to the ‘on’ position. They remain that way with the engine running. The temp gauge however, rests in the far right (hot) position with the engine turned off/cold engine. When I turn the key and flip the switch to the ‘on’ position, the needle returns to the far left and remains there after the engine turns on. As the engine warms up, the needle moves to the right. Back to the engine; I took the original temp sensor ( the one on the drivers side, marked with KS) and installed it on the passenger side where I had a brass plug. Then I installed the new temp sending unit with the two connections on the drivers side. Then I connected the crossover wire to one connection and the wire back to the temp gauge to the other connection point. Side note; When I rewired my car from 6v to 12V using Vintage Auto Garage, the kit came with a voltage reducer. This voltage reducer provides a’ check’ system with red and green lights to warn whether or not the gauges were wired correctly. When two green lights are on, it means the gauges are wired correctly. I have these two green lights. I thought maybe I had a wire crossed with my gauges, but doesn’t appear so.
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| 40 Coupe | -- 12-06-2024 @ 5:35 AM |
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The temperature dash gauge does read Hot when not energized. when the car is turned on it goes to cold and slowly rises with the water temperature increase. If the dash gauge were to stay at the hot position when first turning the engine on then the two terminal sender would be defective. The two terminal sender is normally a closed circuit that when it senses over temperature opens circuit, when the engine cools down the sender resets to the closed position.
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| JayChicago | -- 12-06-2024 @ 7:56 AM |
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Yep, you have it wired correctly, and the gauge is performing as designed. In the end, a job well done. Note all four gauges rest at their worse-case position. Then if a loose/cut sending wire develops, fuel gauge goes to empty, oil pressure goes to zero, voltage meter shows no voltage, and temp. gauge reads hot. I suspect that was Ford engineers trying for "fail safe" design, so driver is warned of a failed gauge.
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| Av68@reagan.com | -- 12-08-2024 @ 10:03 AM |
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Jay & 40 Coupe, I am grateful to you for taking the time to answer my questions and share your knowledge with me about my gauges. It is very much appreciated. I feel accomplished. God bless.
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| 40 Coupe | -- 12-10-2024 @ 4:45 AM |
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Your welcome!
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