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Old 14th May 2017, 23:39   #1
Bolin
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Default How to test coolant sensor wiring is in perfect working order?

Hi all, as titled

How do I test that the wiring going between the engine coolant temperature sensor and the ECU is in perfect working order?

I have a basic multimeter, but not one that buzzes for continuity.

Any advise greatly appreciated.

Thanks, Bolin.
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Old 15th May 2017, 09:40   #2
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Quote:
Originally Posted by Bolin View Post
I have a basic multimeter, but not one that buzzes for continuity.
You can use the lowest resistance range Colin, on each conductor between the sensor socket and the ECM connector.

Simon
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Old 15th May 2017, 10:41   #3
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Quote:
Originally Posted by Bolin View Post
Hi all, as titled

How do I test that the wiring going between the engine coolant temperature sensor and the ECU is in perfect working order?

I have a basic multimeter, but not one that buzzes for continuity.

Any advise greatly appreciated.

Thanks, Bolin.

Why not just run diagnostics on the IPK ? It will show the reading from the sensor in real time. That will be a complete system test.
Or hook up to T4 diagnostics or an alternative ELM type of thingy.
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Old 21st May 2017, 13:57   #4
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You can use the lowest resistance range Colin, on each conductor between the sensor socket and the ECM connector.

Simon
Thanks Simon, could you please explain a bit further for me?

I.e. Do I put one lead on one end of the wire in the engine bay and one on the other end at the ECM connector and then expect what reading on the display if all is OK? (And then repeat for the other wire, logically).

I assume this approach would be the same for the link lead going to the sensor itself?

Lovel - thanks for the suggestion but I was getting nonsensical readings on the OBD, hence needing to test further. I think the problem was air bubbles in the cooling system but ant to check the wiring whilst I have access.
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Old 21st May 2017, 22:05   #5
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Originally Posted by Bolin View Post
Do I put one lead on one end of the wire in the engine bay and one on the other end at the ECM connector ..
Yes. Both connectors should be isolated from their respective components during the test. This is because the meter sends a tiny current along the wire in order to calculate its resistance.
Quote:
... and then expect what reading on the display if all is OK?
Use the lowest resistance range available. Touch the meter probes together and the display should read 0.0Ω. Now apply the probes to the length of wire you want to test. Expect a reading of a fraction of an ohm.

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Old 24th May 2017, 23:30   #6
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Touching the probes gave a reading of about 0.5 ohm.

On the four bits of wires this increased by roughly 0.1 ohm.

All looks OK then.
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Old 25th May 2017, 07:12   #7
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All looks OK then.
Yes. Do you have a fault with the temperature readings then?

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Old 27th May 2017, 17:53   #8
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Yep, probably due to air in the system, currently doing a mini-overhaul of cooling system and then belts & tappets, so hopefully all will be well when finished.

Happy that the wiring has been proven to be OK, I did the test whilst wiggling the wiring as much as possible so am satisfied it is fine, thank you for your help
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