|
|
Coolant Temperature Sensor Help! : ).
|
|
|
| |
|
|
danny20danny
New User
Aug 11, 2015, 1:37 PM
Post #1 of 3
(1412 views)
|
|
Coolant Temperature Sensor Help! : ).
|
Sign In
|
|
Hi all. I will be as detailed as I can..
2007 mercury milan 3.0L v6 sedan
Engine fan only turns on and runs if 2 wire connector to coolant temperature sensor is unplugged.
So when with connector plugged into the coolant temp sensor I turn on the engine. Fan never starts. Coolant level is fine. If I unplug the connector from the sensor the fan turns on and runs continually on high.
Let's test the sensor..
removed sensor and hooked it up to multimeter. on 200k ohms setting it reads 28.8
When lowered into boiling water resistance immediately drops like it is supposed to.. goes down to 4.5 / 4.4 and stops.
Let's test the sensor while installed to make sure hot coolant is running across it...
installed sensor / hooked up multimeter: sensor reads 28.8
Started engine / sensor resistance drops from 28.8 down to 4.3 ( looks like coolant is flowing )
problem persists
Lets check connector pins ( wire leading to sensor )
right side reads 5.5 volts
left side on multimeter ground setting gives tone indicating ground and reads 0.00
looks good
Maybe the pins in the sensor are not making a solid connection inside the connector?.
inserted paper clips solidly in the connector ports and attached alligator clips to each of them...
clipped other side of alligator clips directly to the 2 corresponding male prongs on the sensor.
Started engine. With engine running lowered sensor into a cup of boiling water ( to see if it works with an absolutely sure connection to the connector ).
Nothing...
Took another paper clip and placed it across 2 of the alligator clips to simulate the circuit connecting ( like it is supposed to when the sensor resistance is lowered )...
Fan turned on and ran on high.
I then purchased a Brand New coolant temperature sensor and ran through this entire process again with the new sensor.
problem persists.
Okay. If I know the sensor's resistance is lowering to allow the connection, shouldn't that be causing the same result as me physically closing the circuit with a paperclip and thus starting the fan?. What is happening inside the sensor other than to points connecting when resistance is lowered?.
Any help is greatly appreciated. Thank you in Advance
Danny in Michigan
the fan?.
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 11, 2015, 2:00 PM
Post #2 of 3
(1405 views)
|
|
Re: Coolant Temperature Sensor Help! : ).
|
Sign In
|
|
Just some notes where your test will fail. It will probably (switch) do it's tricks at higher than 212F boiling point for fan? Hard to do without putting water under pressure or use another liquid that wont harm anything for testing.
Tough call. Fire is going to wreck it for testing. Perhaps careful use of a heat gun, maybe hair dryer would get higher temps with air on it - heat gun a definite just don't want to wreck it if not the problem.
Seriously - cooling systems are under pressure and switches for fans and things are frequently above boiling points when they are supposed to work. With heated anti-freeze you still can only get up to about 5 more degrees without pressure before boiling.
Other: These temp sensitive OHM switches of sorts I find if ohms change at all thru the temps they are NOT the problem but rather a connector is more likely,
T
(This post was edited by Tom Greenleaf on Aug 11, 2015, 2:03 PM)
|
|
| |
|
|
Discretesignals
Ultimate Carjunky
/ Moderator
Aug 11, 2015, 5:50 PM
Post #3 of 3
(1396 views)
|
|
Re: Coolant Temperature Sensor Help! : ).
|
Sign In
|
|
Is the engine overheating at stops? Not sure what your trying to figure out here. Do the fans come on with the air conditioning on? Where there any trouble codes stored before you started testing and unplugging stuff?
If the fans come on when you unplug the sensor, you just eliminated wiring, ECU's ability to turn on the fans, the fan controller, and the fan motors themselves. Luckly your not jumping paper clips on 5 volt power supply circuits and shorting them to ground cause you could fry the engine controller's 5 volt regulator if it doesn't have that great of circuit protection. Shoving paper clips into the terminal side of a connector isn't a good thing to do either because now you probably have spread open terminals, which will cause connection problems. If your going to check circuits at the connectors, use a back probe.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Aug 11, 2015, 5:57 PM)
|
|
| |
|
| | |
|
Auto Repair Home
SEARCH
WHO'S 
LOG 
Drive Shaft Repair
2006 Toyoto Camry XLE Driver Side Electric Window Trouble
Grounding Cable, 2017 Jeep Renegade Trailhawk
equipment
Howdy
