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?Measuring resistance?????

Old 10-18-2008, 01:57 PM
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Default ?Measuring resistance?????

I am trying to determine if an ECT sensor is bad. My shop manual directed me to test the resistance between the two connections of my ECT Sensor.

When I did that, I did not receive any reading on the voltmeter. The voltmeter was set to OHMS.

Is this indicitive of a bad sensor.

And if so, can you elaborate what may be going on with the sensor? like an open or closed circuit?

Thanks.....

Just an FYI , it is on a 2002 Honda 130 engine.....

jp
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Old 10-18-2008, 02:22 PM
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Default Re: ?Measuring resistance?????

if it read overload it is an open circuit ...was the meter in auto ?
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Old 10-18-2008, 02:22 PM
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Default Re: ?Measuring resistance?????

I think that You can find a lot of help here:

http://fordfuelinjection.com/?p=28

and be sure that You are using proper ohm scale (in case that You don`t have autorange)




Srdjan

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Old 10-18-2008, 03:07 PM
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Default RE: ?Measuring resistance?????

sea_slueth - 10/18/2008 4:57 PM

I am trying to determine if an ECT sensor is bad. My shop manual directed me to test the resistance between the two connections of my ECT Sensor.

When I did that, I did not receive any reading on the voltmeter. The voltmeter was set to OHMS.
Have you used a VOM (Volt/Ohm Meter) before? Some meters require you to move one lead to a different jack to measure ohms. Touch the meter leads together. The meter should read close to zero ohms, probably one or two ohms. Seperate the leads and it doesn't read anything. Now place the leads on the sensor terminals. If the meter still doesn't read anything or doesn't read what the manual says it should read, it's probably defective. Consult the manual. Also consult the manual for the meter.
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Old 10-18-2008, 04:29 PM
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Default Re: ?Measuring resistance?????

Yes, the meter was set in auto.

It is a "craftsman autoranging multimeter 82040.

Touching the leads together gave me a very low reading that cycled to several readings of resistance.

Once sepearated, it went to zero.

I used my service / shop manual and went through the ECM diagnosis and came to the ect as the problem based on light sequence.

I wish it was only a thermostat as it would be an easy repair. To get to my ECT sensor, I have to remove the intake manifold, throttle case assembly and have the tubing on the starboard side of the engine.

A 17 dollar part is going to take me about 4 hours to fix, if not more.
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Old 10-19-2008, 05:44 AM
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Default Re: ?Measuring resistance?????

sea_slueth - 10/18/2008 7:29 PM

Yes, the meter was set in auto.

It is a "craftsman autoranging multimeter 82040.

Touching the leads together gave me a very low reading that cycled to several readings of resistance.

Once sepearated, it went to zero.
If you are measuring resistance, "zero" is no resistance. One or two ohms is very low resistance. No reading at all is "infinate" resistance. Grasping one probe with one hand and the other with the other hand should give a high resistance reading. A megohm or two.
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Old 10-19-2008, 07:14 AM
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Default RE: ?Measuring resistance?????

Component being measured for resistance must be disconnected from the external circuit. Otherwise, you are reading the equivalent resistance of the component and the parallel external circuit.

(I've never stayed at a Holiday Inn Express, but I was trained in ET "A" school for ten months in 1966... and have an engineering degree too... [img]../jscripts/tiny_mce/plugins/emotions/images/smiley-undecided.gif[/img])
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Old 10-19-2008, 09:56 AM
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Default Re: ?Measuring resistance?????

OK, well, just so I know, the ect (component being measured was disconnected from the system. So if I am getting a zero, does that mean it is defective?

My shop manual gave me several steps to check the ect, then if that was good, move on to the ecm.

I checked the ect and was unsure if I did the test correctly.
So I moved on to the ecm test and I know the ecm is good as it has proper voltage-additionally, I swapped the ecm from my port engine and put it on the problem engine. The same signal codes came up which forces me to believe the ect is the culprit.



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