Coolant Re-Circulation Pump Bora V5

[abreut]

Hi all,

Just wondering if anyone has had their coolant recirculation pump stop working in a V5 Bora and if so figured out why. This is the pump that runs for 10 minutes after switching off the engine

I have confirmed the pump still works by wiring 12v to it. I also checked the fuse and thats all fine and the earth pin is properly grounded. According to the wiring diagram the pump is controlled by the fan control unit. I am suspecting a coolant temp sensor but this seems to be the only thing that has stopped working, has anyone been through this issue? It was working a few weeks ago.

Thanks.

[Bug_racer]

I think there is a check in final control diagnosis to determine if the wiring is ok , I could be wrong

[Golf Loon]

What colour is the coolant temp sensor?

[The_Hawk]

Not sure on the V5, but on the VR6 the fan and pump only run when required, not everytime the car is turned off.

To test the pump and fun on the VR6 you unplug one of the temp sensors and bridge two point and the fans/pump kick on. If yours is similar that would be the way to test it's function without heating up (then trying to play with) the engine.

[abreut]

I'm not sure what colour the temp sensor is, I'll check this afternoon. Its a 4-pin type and its on the plastic thermostat housing like the vr6 ones. One circuit must be working because my temp guage in the instrument panel works fine. My radiator fan comes on as its meant to though I would think that would use a thermo switch (not sure haven't checked).

The car also tends to run not so fuel efficiently and can sometimes do as bad as 14l/100 on a bad day. I''m hoping this is related to the other problem. I suspect it will be similar to the vr6 setup so maybe I can try that bridging test.

If it is a temp sensor would it definitely log a fault?

[Jmac]

Bug Racer is right there you can run a final control function on that pump in engine, if you have Vagcom or access to Vw software
Cheers
Jmac

[abreut]

Thanks for that, I have organised to visit someone with a vagcom cable this weekend so hopefully we will get to the bottom of it. Need to get me one of these cables...

Bug Racer is right there you can run a final control function on that pump in engine, if you have Vagcom or access to Vw software
Cheers
Jmac

[Golf Loon]

Temp sensor wont log a fault, but will make the car use too much fuel and could impact on the run on pump if it thinks the car is already cool.

[abreut]

Temp sensor wont log a fault, but will make the car use too much fuel and could impact on the run on pump if it thinks the car is already cool.

Thats what I'm not sure about as well. Thing is its a 4-pin sensor and one circuit is reading correctly (the instrument panel gauge) so I was thinking maybe the ECU would detect that there was a difference between the 2 and log a fault if thats what the problem is. Just not sure.

[abreut]

Well the good news is I now know that the 2 issues are related. Today I was driving and the fuel economy was back to normal sitting in the 8-9l/100 range and when I stopped the coolant re-circulation pump started working. Later in the day it stopped again and my economy went to crap. It must be the coolant temp sensor.

Bad news is a mate plugged in his vagcom cable and it short-circuited! It was a cheap chinese cable allegedly internally fused but it just started smoking up and cooked its little circuit board. I couldn't believe it I thought it was sayonara ECU for sure. Everything seems to be ok though, car runs, no fuses blown, I shudder to think what damage has been done....

[Jmac]

Yepo sounds like the temp sensor, ah has your car got an aftermarket radio?????? I ask this as this can spike cables, gets a short on the K line

[abreut]

Yepo sounds like the temp sensor, ah has your car got an aftermarket radio?????? I ask this as this can spike cables, gets a short on the K line

You know what I do have an aftermarket stereo and I only just put it in 2 weeks ago. And now that you mention it I used the very same cable without any problems before putting in the new stereo. So have you come across this issue before? Excuse my ignorance but what exactly is the K line and is it fused? I checked every fuse on the fuse panel on the side of the dash and none were blown. I suspect something may be damaged because we tried a different brand of vagcom cable and it could not communicate with the controllers. Or is there a chance that the stereo could be involved again? Jmac You definitely may be on to something here.