I have a 75 Delta 88 with a coolant sensor in the radiator. It has one wire connecting to it and off that wire someone spliced a wire from it to a ring terminal attached to bolt on an AC brachet. This doesn't look right. I have a 1975 Oldsmobile service manual with electrical schematics in it and can not find this sensor anywhere on the drawings. Does anybody have a wiring diagram for this or any ideas?

 

maybe a non standard replacement radiator?

or an anode someone added to the rad ?

 

I found the diagram and trouble shooting pages for the sensor in the service manual post 12-84 and 12-85.
My guess on the wire is the light was staying on and my Uncle grounded out the wire to get the buzzer and light to go out.

 

That is exactly what happened. The "sensor" in the radiator is actually just a metal terminal that uses the conductivity of the coolant to ground the circuit. If the sensor is bad (or coolant is low), the circuit stays open and the light and buzzer go off.

 

I took the probe out and cleaned it up and checked continuity and it's good as new. I'll check tomorrow and hopefully there's not another issue with the circuit.

 

Those things were notoriously problematic even when the cars were new. My 76 Ninety Eight has it and even though I've never had an issue with it, I'd as soon it didn't.

That was about time true service stations started disappearing and lazy/ignorant people didn't know how to check their vehicle's vitals. So, we got coolant level alarms, and tire pressure alarms, and all kinds of bullshit alarms that make lawyers happy but are, in a word, UNNECESSARY for anyone with a smidgen of sense about how to take care of your machinery.

We called such things "nuisance alarms" in powerplant world. It was like the one operator who just had to have a high and low alarm on the cooling lake level, and worried the crap out of everyone until he got it. Then it worried the crap out of everyone else because the range on it was so close that it stayed in an alarm condition all the time.

Let us know if you get the thing functional again.

 

I will. I will be breaking in the engine tomorrow. Fingers crossed.🤞

 

My first instinct was to say that's cute. Engineering is better the simpler it gets, but, this is too cute. Too cute, made by some smirking nerd, usually fails badly. If a float couldn't have been used, I would've run something stupid with a temp sending unit to be happy above 160 in the radiator, and another on the intake to also be happy above 160 and wired the light/buzzer to be happy if both were below 160 (engine cold) and if both were above 160 (warm and full radiator), but go off if the intake saw 160+ but the radiator one did not (as in low coolant, seeing air). Using the "idiot light goes off when you boil over all your coolant" principle here.