RussB

"Secondary Coolant Pump" seems to be another term for "After-Run Coolant Pump".

Q1) The PO of my recently acquired 88 5000CSTQ disconnected the secondary coolant pump and its thermoswitch. I've found the female blade connectors for the thermoswitch, but can't locate the two conductor female connector for the secondary coolant pump. Can anyone help me locate this connector, perhaps with a photograph or a description of where I should look?


Q2) What is the "rule" for when the secondary coolant pump should operate? According to the Bentley shop manual, it operates only when the cooling fan speed 3 is reached (which I think means coolant at the radiator lower hose of about 102-105 deg C). Is this correct?


TIA.

86_5K

Ans1)

<img src="http://astro.uchicago.edu/~mzm/personal/hobby/gif/tempsw2.jpg">

Ans2) It only operates after you shut off the car when the sensor decides that the coolant is too hot. The first stage of the cooling fan will kick in at the same time.

Zhaoming

RussB

I've seen the photo, but it doesn't illustrate the secondary coolant pump (or "after-run coolant pump"). I need to find the two conductors that power the pump.


I agree that the pump runs only when the coolant is too hot -- but only when the coolant exceeds 102 or 105 deg C? That's pretty darn hot.



(Tomorrow I'll simulate coolant of this temperature by shorting the two outer pins of the coolant temperature sensor that resides in the radiator beneath the lower rqadiator hose.)

SteveAngry

Zhaoming said...

Just to add:

A easy test to check the after run pump/low speed fan...

Cross the two wires at the after run sensor. This should activate the after run pump and low speed fan to come on.

If it does not, then you either have a bad fuse, a bad after run relay or a wiring issue.

If it turns on the after run pump then you know that the fuse, relay, after run pump, wiring, etc are good.

Steve
Michigan

RussB

On your car, are both conductors within one two prong connector? From which harness do these two wires sprout? Have a photo of the secondary coolant pump in the engine bay, showing these wires?


TIA