C2 1.4 TDI overheating issues

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Zalupov
Posts: 2
Joined: 26 Jun 2024, 21:41

C2 1.4 TDI overheating issues

Post by Zalupov »

Greetings, I have an old 2007 C2 1.4 TDI, VIN VF7**************[VIN obfuscated, can be read by forum staff]. We've rebuilt the engine over the past month, changed a lot of stuff and managed to fix most of the problems, however the last one still persists - the engine overheats. While trying to solve this we managed to realize that the ECT sensor isn't actually connected to the ECU, but gets 12V(instead of 5 or maybe even 2) from somewhere, meaning that someone tried 'fixing' this car before us and failed miserably.
Two ECT sensors are already dead(no resistance could be measured), however the ECU still thinks the coolant temp is around 28 degrees C nearly all the time, even when the engine intake temp is above 60C.
We suspect there is some kind of static resistance connected to the ECU somewhere in the loom, but getting the engine out for the fifth time and unwrapping the whole loom because of it sounds a bit excessive, so we decided to make a shortcut and just connect the sensor directly to ECU, we just need to know what pins it should be connected to.
Please share the electrical scheme if you have one for this car, we could only find the ones for other models/engines online and they don't seem to fit.
Thanks in advance.
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GiveMeABreak
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Re: C2 1.4 TDI overheating issues

Post by GiveMeABreak »

I've deleted your other post - please don't duplicate posts for the same issue. You'll just have to be patient until somebody has the time to help - with hundreds of posts a day we can't always get round to everyone as quickly as they'd like!

Now that I've seen your post, I may be able to help.

Here is the cooling circuit for you:

With the exception of the wiring codes, most of the component codes are indexed here:

PSA Electrical Diagrams - Wiring & Symbols Codes Index

Cooling
Image

Engine ECU

Image
Please Don't PM Me For Technical Help

Marc
Zalupov
Posts: 2
Joined: 26 Jun 2024, 21:41

Re: C2 1.4 TDI overheating issues

Post by Zalupov »

Thanks for the schemes!
Found the static resistance as previously assumed
rstns.jpg
Repinned new wires directly to the sensor and now everything works as intended, the car didn't overheat even with 36С outside while we were stuck in a jam for half an hour.