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How do I check the ECT sensor? Use of Multi-meter!

AlanS

New member
Joined
Aug 22, 2004
My ECT sensor is possibly not working on my 95- 850. In order to get an exchange, I need to PROVE it's bad. I don't want to be embarrassed, so I picked up a multi-meter.
OK...I got a Multimeter. I am electronically ignorant...a moron! The Ohms section has 5 choices: 2000K, 200k, 20k,2000, 200. What do I set it on for testing the ECT sensor? What am looking for? A simple explanation would be helpful...make believe you are talking to a 5 year old...an not a bright one!!!
 
Set the ohmmeter to the 20K range.
Depending on sensor temperature you should get the following results:
COOLANT TEMPERATURE SENSOR RESISTANCE TABLE
Temperature - F ( C) Ohms
32 (0) ...........................7300
68 (20) ........................ 2800
176 (80) .........................300
212 (100) .......................150
 
Set the ohmmeter to the 20K range.
Depending on sensor temperature you should get the following results:
COOLANT TEMPERATURE SENSOR RESISTANCE TABLE
Temperature - F ( C) Ohms
32 (0) ...........................7300
68 (20) ........................ 2800
176 (80) .........................300
212 (100) .......................150
OK...so here's what I did:
Engine cold...85 degrees out all day. The meter set at 2000, the reading was 1740, at 20K 1.75....I let it heat up to operating temp (via the interior gauge): at 2000= 225, at 20K .25 This kinda corresponds to your chart, but not exactly. It did go down!
So, if it's not the sensor, then I guess it's the leads going to the sensor...those barrel connections that I can't get inside of to clean. I used a very small jewlers file to try to rough up the inside of the barrel, but the Code still comes up.
Any ideas?
 
Yes, replace the thermostat. The ECU allows a set amount of time for the engine to reach operating temperature, if your stat is sticking partially open it won't reach operating temp in time and will trip a code for the ECT.
 
Yes, replace the thermostat. The ECU allows a set amount of time for the engine to reach operating temperature, if your stat is sticking partially open it won't reach operating temp in time and will trip a code for the ECT.
GEEZ, I just replaced the stat when I replaced the sensor. So, you feel that the sensor IS working? Does the Stat have a 'proper' orientation? I saw a small hole in the frame of the thermostat, but just put the darn thing in. BUT, this combo (new stat/ new sensor) worked for about one month.!
 
The hole in the stat is a bleed to prevent air being trapped in cooling system and the hole goes up.
Did you replace the stat with the same temp rating? Was it a Volvo stat or aftermarket stat? Do you suspect wiring as the fault?
Many a new stat are junk.
 
What are the resistance values for the 2.4/Regina ECT? I’m getting roughly 530 ohms at operating temp

Over 200f and getting 400 ohms
 
Last edited:
What are the resistance values for the 2.4/Regina ECT? I?m getting roughly 530 ohms at operating temp

Over 200f and getting 400 ohms
That seems a bit high, but are you measuring correctly?
There are 2 separate resistors in the sensor; 1 for ignition, 1 for fuel.
You measure each pin separately to ground, not to each other.

Here's a chart I borrowed from Autozone...

<img src="http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/c6/98/large/0900c1528008c698.gif"width=600></a>
 
That seems a bit high, but are you measuring correctly?
There are 2 separate resistors in the sensor; 1 for ignition, 1 for fuel.
You measure each pin separately to ground, not to each other.

Here's a chart I borrowed from Autozone...

<img src="http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/c6/98/large/0900c1528008c698.gif"width=600></a>

Oops did not know that.
 
Unless yours is a freak of nature...
Ignition box (by steering column) - Pin 2 red/black
Fuel box (behind right kick panel)- Pin 13 grey/white

I've got a piece of paper in the car to remind me (whenever I get ambitious and decide to finally check mine). Might just fix the loooooooong crank before it starts. :-P
 
Unless yours is a freak of nature...
Ignition box (by steering column) - Pin 2 red/black
Fuel box (behind right kick panel)- Pin 13 grey/white ...

And if your is the 240 in sig, the ignition cu terminal (at passenger's toes) pin 2 is blue/red
and fuel box (just like in the 7/9) pin 13 is also blue/red if that's not freaky. :-D
 
Unless yours is a freak of nature...
Ignition box (by steering column) - Pin 2 red/black
Fuel box (behind right kick panel)- Pin 13 grey/white

I've got a piece of paper in the car to remind me (whenever I get ambitious and decide to finally check mine). Might just fix the loooooooong crank before it starts. :-P

I had an extended crank time when I had a bad fuel pressure regulator. Like a reallllly long crank. It was especially bad when warm since the engine didn’t require as much fuel as it does when cold.
 
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