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I'm installing a NOS Harley/Stewart Warner cylinder head temp gauge on my 79 FLH and need help with the connections on the gauge. The red and black wires are connected to the ring that goes under the spark plug. I realize I need 12v to the terminal marked 12v ignition. I don't know which terminals to connect the red and black wires to. Can someone advise?
Years ago I had a 79 FLH as well and installed a head temp gauge. Mine did not have a ring terminal under a spark plug. It had an actual threaded sending unit that required drilling a hole in one of the cooling fins, and was held in place with a thin jam nut threaded onto the sending unit from the underside of the cooling fin.
12 volts went to the 12v IGN terminal, frame ground to the GND terminal and the wire from the sending unit to the unmarked terminal.
Are the orange and white wires attached to the ring terminal fabric insulation? They look like the wire covering on cars from the 60's that had resistor wires to drop the coil voltage.
Yes the black wire connects to the white wire on the ring terminal and the red wire connects to the orange. I think there is a thermistor in the orange/white wiring. Pic attached. The one that you had where it installs into a head fin is another type of sender that I'm familiar with.
The one I installed on my 79 came in a kit that had a conical shaped housing that mounted to the handlebars with a clamp, the gauge, sending unit, wiring harness and some miscellaneous hardware and crimp on wire terminals. The housing had a chrome bezel for the gauge and the housing body was wrinkle finish black.
The part # for the gauge kit is 75000-69A, the gauge part # is 75002-77 and the wiring harness part # is 75003-69. The wiring harness diagram in the parts manual shows it for use with a sending unit.
Do you have the part # for the NOS gauge kit you have? If so I have a 1971 to 1980 parts manual and could see if your part # comes up.
I just went out and looked in a box with some NOS parts I still have and found an NOS sending unit # 75005-69. There's also a # 75005-77 sending unit that's for a temp gauge with light.
Last edited by 1Fordman; Apr 20, 2020 at 11:18 PM.
Your 75002-69 is listed as temperature gauge with light, sending unit and spacer. The part # changed to 75002-69A. You would need to find out if the SW 280-LK sending unit is for your application.
There is nothing in the HD parts book that even looks close to the SW sending unit.
Before I go looking for the sender that goes into a cylinder fin, I just found the Harley part numbers for the gauge wiring I have. The ring terminal part is 75041-84 and the wiring extension is 75042-84. Anyone know how this is connected to the gauge 75002-69?
I don't know if this helps, VDO and Dakota Digital both make cylinder head temp gauges that use the 14mm ring terminal under the spark plug. The Dakota wiring diagram shows red +12volts, black to ground and a blue for lighting. The 2 wires from the ring terminal attach to wiring that goes into the gauge to compute the cylinder head temperature. VDO wiring is very similar. Both gauges have 6 pin wire terminals on the back side.
The ring terminal and wiring is called a thermocouple.
I dont believe your gauge and ring terminal sender are compatible with each other. Your gauge (75002-69) is made for use with the sender mounted to a fin.
Analog gauge and a digital sender don't play well together.
Hello. Would you be willing to sell the sending unit? I have a 83 FLHT that I have this installed on and the sending unit is bad.
Please let me know. I'd like to purchase it from you if you are willing.
Thank You.
Jason
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Vintage cylinder head temp gauge connecting
