Discussion
Right. Now I'm no longer sidetracked by hiscocks' C6, I need your help. This is one for the technical 306 geek.
Phase 3 (I think) 306. '99, V-reg. 1360 petrol. LX trim (with aircon).
My cooling fans come on full bore about 1.25654 seconds after the engine has started from cold and settled to an idle. With the ignition in position 1 (the one after off), the fans are on slow.
I thought it was the sensor, so I shorted the sensor wiring out with a paperclip. The fans stopped. I thought it was solved so went and spent £30 on a temp sensor from Peugeot. I fitted the new sensor. Nothing changed.
There are three coolant temp sensors on this one:
Now, why the farp has the new sensor not cured the problem?
I've measured the resistance of the sensor when hot. ~2.7kOhm.
I've measured the resistance of the sensor when cool (2hrs after a 5mi run home from work). 2.1kOhm.
This suggests it's a positive temp coefficient resistor; low resistance when cold. Judging by the success of the paperclip test, this is what it should be. The low resistance paperclip is spoofing a cold PTC sensor. However, I would have expected a much lower resistance when cold.
I've taken the plug apart on the brown sensor, and passed a bit of emery through the contacts. Then reassembled with a bit of silicone grease to keep the water out (there was slight evidence of corrosion).
So I've either been supplied with the wrong sensor. Unlikely.
Or I've been supplied with a duff sensor. Also unlikely.
Or there's something else happening that I don't understand. More likely.
HELP. This is really hurting my mileage. And my OCD!
Phase 3 (I think) 306. '99, V-reg. 1360 petrol. LX trim (with aircon).
My cooling fans come on full bore about 1.25654 seconds after the engine has started from cold and settled to an idle. With the ignition in position 1 (the one after off), the fans are on slow.
I thought it was the sensor, so I shorted the sensor wiring out with a paperclip. The fans stopped. I thought it was solved so went and spent £30 on a temp sensor from Peugeot. I fitted the new sensor. Nothing changed.
There are three coolant temp sensors on this one:
- One in the block (blue plug in picture), that controls the temp gauge.
- One in the top of the 'thermostat housing' bit (green plug), that tells the ECU about cool running enrichment. This has been recently replaced to cure a cool running issue.
- One in the front of the 'thermostat housing' (brown plug), directly by the actual thermostat. This is the suspected issue.
Now, why the farp has the new sensor not cured the problem?
I've measured the resistance of the sensor when hot. ~2.7kOhm.
I've measured the resistance of the sensor when cool (2hrs after a 5mi run home from work). 2.1kOhm.
This suggests it's a positive temp coefficient resistor; low resistance when cold. Judging by the success of the paperclip test, this is what it should be. The low resistance paperclip is spoofing a cold PTC sensor. However, I would have expected a much lower resistance when cold.
I've taken the plug apart on the brown sensor, and passed a bit of emery through the contacts. Then reassembled with a bit of silicone grease to keep the water out (there was slight evidence of corrosion).
So I've either been supplied with the wrong sensor. Unlikely.
Or I've been supplied with a duff sensor. Also unlikely.
Or there's something else happening that I don't understand. More likely.
HELP. This is really hurting my mileage. And my OCD!
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