How to read ECT voltage/resistance from ECU?
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How to read ECT voltage/resistance from ECU?
Well. I don’t know much about electronics and ****. So. Replaced the coolant temp sensor because I was having hard warm starts.
Anyways, I replaced it with a new one, now my car starts perfectly when warm.. however, it doesn’t start when the engine is cold now.. unless I give it lots of throttle and keep the RPMs up until it warms up some.
I tested the sensors resistance and got normal numbers, so I think she sensor is fine... however, I tested the resistance from the plug to the ECU and this is the reading I got... is this normal?
How can I test the plug from the ECU side so I can test while the engine is running with the plug connected to the sensor?
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From: Orlando FL
I don't know if there is a "standard" reading between the connector and the ECM. There is no resistance built into that circuit and how the ECM computes temperature is the resistance through the circuit. You go from typically very little reference voltage when cold to a full voltage reference when "hot".
The connections are typically checked for continuity between the terminal and the other end of the harness at the pin for the computer. What year is your car?
The connections are typically checked for continuity between the terminal and the other end of the harness at the pin for the computer. What year is your car?
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I don't know if there is a "standard" reading between the connector and the ECM. There is no resistance built into that circuit and how the ECM computes temperature is the resistance through the circuit. You go from typically very little reference voltage when cold to a full voltage reference when "hot".
The connections are typically checked for continuity between the terminal and the other end of the harness at the pin for the computer. What year is your car?
The connections are typically checked for continuity between the terminal and the other end of the harness at the pin for the computer. What year is your car?
no mo volvo
Joined: Oct 2010
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From: 37 North on the left coast
to measure the CTS resistance from the ECU, you unplug the ECU and measure the resistance of the CTS pin to a ground pin at the ECU plug. ideally you also do this at the ICU as the CTS has two elements, one connected to each of the ICU and ECU.
the CTS is an inverse resistance thing, its high resistance when cold, 10 or 20k ohms, I think? and low resistance when hot, like 600 ohms or something. the correct values are in the 7xx/9xx FAQ for LH 2.4 cars.
the CTS is an inverse resistance thing, its high resistance when cold, 10 or 20k ohms, I think? and low resistance when hot, like 600 ohms or something. the correct values are in the 7xx/9xx FAQ for LH 2.4 cars.
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to measure the CTS resistance from the ECU, you unplug the ECU and measure the resistance of the CTS pin to a ground pin at the ECU plug. ideally you also do this at the ICU as the CTS has two elements, one connected to each of the ICU and ECU.
the CTS is an inverse resistance thing, its high resistance when cold, 10 or 20k ohms, I think? and low resistance when hot, like 600 ohms or something. the correct values are in the 7xx/9xx FAQ for LH 2.4 cars.
the CTS is an inverse resistance thing, its high resistance when cold, 10 or 20k ohms, I think? and low resistance when hot, like 600 ohms or something. the correct values are in the 7xx/9xx FAQ for LH 2.4 cars.
Do you have a diagram on the ECU of which pin is the CTS pins?
no mo volvo
Joined: Oct 2010
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From: 37 North on the left coast
its ECU pin 13, and also ICU pin 2 on LH 2.4 cars (1989+ non-turbo and 1990+ turbo). ECU ground is pin 5, ICU ground is pin 11. measure the resistance at the ICU or ECU plug, with it unplugged from the ECU/ICU,
resistance of the sensor should be as follows:
32F - 6000 ohms
68F - 2300 ohms
104F - 1300 ohms
140F - 600 ohms
176F - 300 ohms
212F - 190 ohms
all within about +/- 10%
I'd suggest getting the engine nice and hot, pulling the plug measuring it for the warm value, then wait for it to cool down to ambient and measure it again.
https://www.volvoclub.org.uk/faq/Eng...ingECTFailures
resistance of the sensor should be as follows:
32F - 6000 ohms
68F - 2300 ohms
104F - 1300 ohms
140F - 600 ohms
176F - 300 ohms
212F - 190 ohms
all within about +/- 10%
I'd suggest getting the engine nice and hot, pulling the plug measuring it for the warm value, then wait for it to cool down to ambient and measure it again.
https://www.volvoclub.org.uk/faq/Eng...ingECTFailures
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its ECU pin 13, and also ICU pin 2 on LH 2.4 cars (1989+ non-turbo and 1990+ turbo). ECU ground is pin 5, ICU ground is pin 11. measure the resistance at the ICU or ECU plug, with it unplugged from the ECU/ICU,
resistance of the sensor should be as follows:
32F - 6000 ohms
68F - 2300 ohms
104F - 1300 ohms
140F - 600 ohms
176F - 300 ohms
212F - 190 ohms
all within about +/- 10%
I'd suggest getting the engine nice and hot, pulling the plug measuring it for the warm value, then wait for it to cool down to ambient and measure it again.
https://www.volvoclub.org.uk/faq/Eng...ingECTFailures
resistance of the sensor should be as follows:
32F - 6000 ohms
68F - 2300 ohms
104F - 1300 ohms
140F - 600 ohms
176F - 300 ohms
212F - 190 ohms
all within about +/- 10%
I'd suggest getting the engine nice and hot, pulling the plug measuring it for the warm value, then wait for it to cool down to ambient and measure it again.
https://www.volvoclub.org.uk/faq/Eng...ingECTFailures
What's the best way to reach these pins? I saw the ICU ( Black box on the firewall? ) and I saw the ECU ( Silver box on the right side of the passenger foot well ), how do I go about getting to the pins?
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Thanks for all the replies and help. I'm good with mechanical things, but wiring and electrical stuff confuses me a bit!
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