We were rebuilding tampered wirings in my friends 1980 Aspen with Super Six. We had to take the electric ignition wiring harness (the one with 8 pin connector, passenger side inner fender) from the identical parts car with the same engine.

The intake manifold has two threaded holes in the 6th cylinder runner. The one is for manifold vacuum T-fitting and the other has some sort of electrical sender. There's two electrical connectors in the sender - one stud and one flat male, which I presume to be grounding. What is this thing? There were wire connectors for this device in both the old and the new harness, but they weren't connected previously.

The other thing we don't know was the small relay, which came with the new harness. An aluminum round relay, 1" diameter, 1" tall, two wiring connectors. Like a turn signal relay, but smaller. The relay has a mounting bracket with one 5/16" hole. Identical cars but no such relay in the old harness.

The car seemed to run without these electrical devices, but it would be nice to know what are their purpose so we can connect them correctly. Electric ignition is the 4-pin model, blue ECU-box and the single ballast.

Sorry about the unclear description and no pics. I'll try to remember to take photos if we don't figure out the problem before that.

Thanks for any ideas.

The sensor in the intake runner is the "air charge temperature sensor." It senses the temperature of the air/petrol mixture in the intake manifold. This sensor is used with the computer controlled carburetor and ignition systems, but is not necessary if you have removed the computer controlled systems.

I don't know what the other relay might be.

Thanks for the quick answer.

Don't know about any computers that control the carb. The carbs in both engines are Carter BBD with no electrical gadgets. There is no Lean Burn. The donor car had EGR time delay system in place.

We detached the whole engine and instrument panel wiring harnesses so we know every box and relay that are in there.

Both cars are export models. Maybe the same models were shipped to Canada, because underhood warning decals are in English and French.

The sensor in the intake is most likely for the EGR timer. It has been some time since I examined that system. However, no matter what the sensor is for, you do not need it if you are not using a computer controlled carburetor, ignition, or an EGR system.

Ok, here's some pics of the relay.

If I am correct, it is for the choke .One of the plugs is for a power wire , and the other is for the wire on the choke to heat up the coil. I have one on my truck , and that is what it is used for.

Dave

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81 Dodge D150
It looked easier in the book .

Actually, it is just a thermal switch. It is wired into the electric choke circuit. It is wired in parrallel with the choke resistor, and in series with the choke heater element. When the engine is cold, the switch is open, and all the current to the choke flows thru the resistor. When the engine is "warmer", the switch is closed and the current bypasses the resistor, and allows the choke to open quicker.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks for the answers. The choke thermal switch -explanation sounds reasonable. I must check the wiring diagrams from Chilton's manual and measure them in the car. Currently there's no choke coil or the choke control unit in the car so we have to find those first.

And switch is supposed sense the engine compartment temperature, since it's mounted somewhere in the compartment. Is there any more specific place for the switch?

It has been awhile since I have seen one on a slant six. If I remember correctly it gets bolted the the cylinder head, at rear most engine lifting bolt hole.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I checked few photos of engine compartments and it seems this thermal switch bolts on the front engine lifting thread. I have often seen the vacuum amplifier bracket to bolt in the rear one in late model Aspen/Volare.

Is the choke control unit (single or dual stage) used at all, when the car is equipped with this kind of thermal switch?

Yes it is used, the switch you have is a single stage control unit. Electrical current is supplied to this unit from the oil pressure switch. A minimum 4 psi oil pressure is nesessary to close the contacts in the oil pressure switch and feed electrical current to the choke control switch and from there to electric assist heating element (in the choke assembly).
A single stage control shortens only summer choke duration, below 55 F the electric heat is not available until the engine approaches normal operation temperatures.