Discussion
The fans aren't coming on.
I checked the fuses and they're fine. I've wired up a manual override, so I know the fans themselves are working, and the connectors to the fans are looking in fairly good shape.
I'll replace the relays once I get chance to run down to Lucas to pick them up, but I'm thinking that its pretty unlikely that BOTH relays have gone simultaniously (although the car has the Trackcar cooling chip - does that connect the two fans together???).
Failing that am I looking for a wiring fault?
Any thoughts or help most gratefully received...
N
I checked the fuses and they're fine. I've wired up a manual override, so I know the fans themselves are working, and the connectors to the fans are looking in fairly good shape.
I'll replace the relays once I get chance to run down to Lucas to pick them up, but I'm thinking that its pretty unlikely that BOTH relays have gone simultaniously (although the car has the Trackcar cooling chip - does that connect the two fans together???).
Failing that am I looking for a wiring fault?
Any thoughts or help most gratefully received...
N
If the Fans work when you 'hot wire' them, then I'd say you have air in the system - not uncommon in the Cerb. Bleed the system, easy job, it only takes 10 minutes.
With the engine ecold, and the car on level ground, or at least with the front slightly higer than the rear. Undo the Big nut on the side of the radiator (driver side) then fill the expansion tank until water starts to be expelled from it, then tighten it back up. Repeat this with the Bleed valves on the cooling rails until all he air is expelled. Then start the engine up, and wait for the fans to come on.
With the engine ecold, and the car on level ground, or at least with the front slightly higer than the rear. Undo the Big nut on the side of the radiator (driver side) then fill the expansion tank until water starts to be expelled from it, then tighten it back up. Repeat this with the Bleed valves on the cooling rails until all he air is expelled. Then start the engine up, and wait for the fans to come on.
As far as I know - and I could be wrong - the ECU picks up the temperature from the Sensor under the front panel in the engine compartment. Have you bled the system yet? If there is air in the cooling system it will prevent the fans coming on. You can try all sorts of fault finding procedures, but if you haven't bled the system you may well just end up chasing your tail and getting nowhere.
Just fixed the very same problem on mine. The fans DO NOT come on , on an open circuit from the sender. The sensor is beneath the F1 panel in front of the engine on the bottom pipe under the windscreen wash bottle, the wire is marked temp sensor. It plugs on, wire was broken in the plug on mine, temporary fixed with small spade crimps until I can source a new plug.
JensenA said:
Have you bled the system yet? If there is air in the cooling system it will prevent the fans coming on. You can try all sorts of fault finding procedures, but if you haven't bled the system you may well just end up chasing your tail and getting nowhere.
Not yet - I was asking about the temp sensor so that I can check the situation with the fans after the bleed without having to get the engine up to temperature, but as that little trick doesn't work, I'll just have to do it the conventional way.Hook up a laptop with the software
It will show you what temp the ECU thinks the coolant is at and it shows when the ECU has turned the fans on.
If the ECU says they are on but they aren't running its a supply fault to the fans.
If the ECU says they are off then its likely not getting a sensible temp reading from the sensor - corroded connector/broken cable/air lock hence no heated water around the sensor
It will show you what temp the ECU thinks the coolant is at and it shows when the ECU has turned the fans on.
If the ECU says they are on but they aren't running its a supply fault to the fans.
If the ECU says they are off then its likely not getting a sensible temp reading from the sensor - corroded connector/broken cable/air lock hence no heated water around the sensor
Tominski said:
Where / Which is the fuse / relay for the fan??
O only have the one fan on mine, have applied 12v to the fan and it spins, but not gettin it come on when the engine is running.
Thanks
On a 4.5 the two fan fuses are the end two at the passenger compartment end of the fuse box. Likewise, the two relays are the furthest two down the same end. O only have the one fan on mine, have applied 12v to the fan and it spins, but not gettin it come on when the engine is running.
Thanks
I know it's different on a 4.2, but I don't have a 4.2 fusebox diagram to hand.
May also be different on cars with only one fan...
Nefarious said:
JensenA said:
Have you bled the system yet? If there is air in the cooling system it will prevent the fans coming on. You can try all sorts of fault finding procedures, but if you haven't bled the system you may well just end up chasing your tail and getting nowhere.
Not yet - I was asking about the temp sensor so that I can check the situation with the fans after the bleed without having to get the engine up to temperature, but as that little trick doesn't work, I'll just have to do it the conventional way.
ETA: That sounded nastier than I was thinking it - no offence meant
Edited by JensenA on Monday 28th April 17:48
In case anyone's interested, it was the relays. Both at once, bizarrely.
To correct what I said a couple of posts back the second fan fuse is third from the end not second, and whatever you do, don't pull it with your keys in the car, as it also works the alarm.
As an aside, hooking the laptop up is great - first time I've done it. Not only does it appeal to my inner geek, but it also happens to be school kicking out time, so sitting blipping the throttle, playing with the software while I was waiting for the engine to warm up attracted quite a crowd.
To correct what I said a couple of posts back the second fan fuse is third from the end not second, and whatever you do, don't pull it with your keys in the car, as it also works the alarm.
As an aside, hooking the laptop up is great - first time I've done it. Not only does it appeal to my inner geek, but it also happens to be school kicking out time, so sitting blipping the throttle, playing with the software while I was waiting for the engine to warm up attracted quite a crowd.
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