1981 Engine Fan Electric

[gambit]

My electric cooling fan on the radiator never runs. It is plugged up and is pluged into the tempature switch. Anybody know how to test to see if its the fan motor or the tempature senser or anything else? Its not the fuse, I checked that already. I tried to run the engine, and unplugged the tempature sensor and touched it to the engine block to ground it out as the repair manual suggested but it didnt do anything.

 

[GerryLP]

My electric cooling fan on the radiator never runs. It is plugged up and is pluged into the tempature switch. Anybody know how to test to see if its the fan motor or the tempature senser or anything else? Its not the fuse, I checked that already. I tried to run the engine, and unplugged the tempature sensor and touched it to the engine block to ground it out as the repair manual suggested but it didnt do anything.

Connect a toggle-switch to the temperature switch's terminals with one side of the toggle-switch wire to an aligator clip and the other to another aligator clip. Make sure that they don't contact each other. Activate the switch.

GerryLP:cool

 

[gambit]

Im not sure I understand....... that sounds like I am shorting out the two wires to see if it makes the fan run, but you said to be sure not to let the clips touch, but that would just be the same thing as if I flipped the switch correct? You do mean the two wires that connect that lead down to the fan right?

 

[Wegone]

The fan will not come on untill the temp is around the high 220s to low 230s as for testing it one side of the plug should be + and the other - just hook 12volts to it.

 

[GerryLP]

Im not sure I understand....... that sounds like I am shorting out the two wires to see if it makes the fan run, but you said to be sure not to let the clips touch, but that would just be the same thing as if I flipped the switch correct? You do mean the two wires that connect that lead down to the fan right?

I have shorted the two terminals before; however, the best way to do that is by placing some resistance between the two terminals. I believe that Corvette Central has a kit that does just that with a toggle-switch.

GerryLP:cool

 

[LannyL81]

You should be able to just short the two wires together as that is what the temperature switch does. You are looking at the one in the passenger side head right?

Better is to do as suggest: unplug the fan two wire harness and apply 12 volts them. Just be sure to get the polarity correct.

 

[gambit]

Hey thanks, No Im lookin at the one on the drivers side head up front, one wire going to it. There is a plug on the rear of the passengers side with two terminals but nothing is plugged to it.

 

[GerryLP]

Hey thanks, No Im lookin at the one on the drivers side head up front, one wire going to it. There is a plug on the rear of the passengers side with two terminals but nothing is plugged to it.

Gambit,

That plug uses the black and the blue (I believe) wire that are part of the starter jumper harness. The black wire should have a split at a grounding gromet end.

It these wires are not connected or missing, then there is your problem.

GerryLP:cool

 

[gambit]

AHHHH!!!!!! THERE IS MY PROBLEM!. I was looking on the Drivers side for the plug, that wire was the Oil Tempature Sensor so I now Know.

On the Passengers side there is a sensor at the rear of the head with two prongs, but nothing plugged into it. I looked at the starter wiring harness near the starter and there are no unused wires there, I looked at the plug at the top of the harness and something looks fishy. Can anyone help me figure out two things

1. Why would somebody cut away the wires
2. How to fix it!! : )

There are 6 holes in the plug, two rows, three top and three on the bottom.
Color is faded but this is what it looks like to me

Toprow Left Red with white strip in, Red out, goes to starter
Toprow Center - teal green in, short blue wire out that has been cut off
Top Row Right - Some wire in but cut off, no wire out.
Bottomrow Left - Purplish color in, Brown out down to starter
Bottomrow Center - Red In, Red out down to starter
Bottomrow Right - empty in empty out.

Gambit,

That plug uses the black and the blue (I believe) wire that are part of the starter jumper harness. The black wire should have a split at a grounding gromet end.

It these wires are not connected or missing, then there is your problem.

GerryLP:cool

 

[LannyL81]

AHHHH!!!!!! THERE IS MY PROBLEM!. I was looking on the Drivers side for the plug, that wire was the Oil Tempature Sensor so I now Know.

On the Passengers side there is a sensor at the rear of the head with two prongs, but nothing plugged into it. I looked at the starter wiring harness near the starter and there are no unused wires there, I looked at the plug at the top of the harness and something looks fishy. Can anyone help me figure out two things

1. Why would somebody cut away the wires
2. How to fix it!! : )

There are 6 holes in the plug, two rows, three top and three on the bottom.
Color is faded but this is what it looks like to me

Toprow Left Red with white strip in, Red out, goes to starter
Toprow Center - teal green in, short blue wire out that has been cut off
Top Row Right - Some wire in but cut off, no wire out.
Bottomrow Left - Purplish color in, Brown out down to starter
Bottomrow Center - Red In, Red out down to starter
Bottomrow Right - empty in empty out.

There is a coolant temp sensor in the driver's side head. The oil temp sensor goes in just above the oil filter, although my 81 manual says this is where the oil pressure sensor is at....wrong....its behind the distributor.


Top Row Center...under the connector index tab...the teal green wire in goes to the blue wire. You can get a replacement connector from either GM or auto parts store that goes onto the fan switch sensor in the passenger side head. The blue wire goes to one side of the sensor, a black ground wire goes to the other. It does not make a difference as the sensor just shorts the two when temp is hot enough.

I have taken a picture of the connector in my car, send me an email and I will send you the picture.

deanvette@comcast.net is my email address.

Later,
Lannyl81

 

[GerryLP]

AHHHH!!!!!! THERE IS MY PROBLEM!. ...
2. How to fix it!! : )....

The wires look like gauge 12 or even gauge 10. The black wire is a "Y" pig tail with a washer terminal (is that the name?) that holds both length of black wire. The washer terminal goes on your tranny bellhousing. One leg goes to the connector on pictures, and the other goes to one of the blades on temp switch. The blue wire goes from connector to the other blade terminal for temp switch.

View attachment 11338

GerryLP:cool

 

[gambit]

Ok let me get this straight. The blue wire I got, the black wire Im fuzzy on. I do see a black wire that comes out of the starter bundle (but is not attached to the pulg anywhere) and is pigtailed and both ends of the pigtail are attached to the transmission bell housing. You say one end of the pig tail should go to the tempature switch? and one end should lead back up to the plug? Which port of the plug does it connect into? Does it matter which side of the tempature sensor that each wire plugs into?

Thanks alot

 

[GerryLP]

Ok let me get this straight. The blue wire I got, the black wire Im fuzzy on. I do see a black wire that comes out of the starter bundle (but is not attached to the pulg anywhere) and is pigtailed and both ends of the pigtail are attached to the transmission bell housing. You say one end of the pig tail should go to the tempature switch? and one end should lead back up to the plug? Which port of the plug does it connect into? Does it matter which side of the tempature sensor that each wire plugs into?

Thanks alot

See view "C". The black wire goes on the starter harnes to the connector at the heater exchanger. From there, it has a washer-type connector were the two black wires split, and the remaining leg has a blade terminal female that connects to the switch. Either blade connector on the switch can have either wire.

GerryLP:cool