14 replies to this topic

[Ledlights]

A strange one this, the fan starts up before the engine gets to temperature but the temp gauge works as it should and the sensor appears to change resistance with temperature as per other posts. I’ve also checked the wiring and can’t see any chafing. The fan runs continuously until you switch the engine off again.
I thought that the ECU and gauge took their reading from the same temperature sensor on the thermostat body but I don’t understand why the gauge would read just above the minimum when the fan switches on, whilst also going on to read normal operating temperature once the engine warms up.
Any ideas?
Thanks, Steve

[Quinlan minor]

Has the car had the recall fix?

The original temperature sensor cables were too short, allowing engine movement to stress the conductor in the cable.

Since, as with most Engine Management systems, a component, or connection, fails to "Safe", if the continuity in the cable is broken the fan will be switched 'On'.

Minispares has the Harness Coolant Fan Modification. Rover Tech Bulletin 0043, in stock.

 

Sign up to TMF +. Message Simon, at Mini Spares, and get £1.25 discount (25% of your annual subscription) and 7.5% off any other items you may need.

 

 

 Cable.jpg   40.46K   1 downloads

[Ledlights]

Thanks for your reply. I’ll check for the recall fitment but if there is a continuity problem, wouldn’t that cause the temp gauge to read low or not read at all?
Thanks, Steve

[Quinlan minor]

Having had the issue, the temp gauge on mine registered normally, replacing the cable meant the fan only came on at the appropriate times.

I imagine the gauge is a fed multiple sample resistance output but one open circuit reading triggers the fan.

If you want to, you could try disconnecting the wire, shortly after starting from cold, to see what happens

[Ethel]

Does it not have a thermal switch in the radiator? I'm sure some Minis with auxiliary fans do, operates independent of the gauge. 

[Quinlan minor]

Does it not have a thermal switch in the radiator? I'm sure some Minis with auxiliary fans do, operates independent of the gauge. 

Not on the MPi, Ethel.

[Ethel]

Ok, didn't  didn't realise it was an MPI, not that I'd have been that much wiser....

 

I think I'm right in thinking there's a relay and the ECU will likely control it by sinking (earthing) the earth. So it could be the relay, or a related earth fault

[Ledlights]

I’ve just checked the car and the update to a brown plug has already been done. Is there anywhere else the loom might have failed?

[Ethel]

Wiring diagram shows a light green/ black trigger wire running from the relay to 28 on the ECU.

[Quinlan minor]

Remove the brown plug and inspect the terminals inside for signs of corrosion, same with the sensor.

[Ledlights]

The sensor and plug appear to be in reasonable condition with no corrosion. However, if the plug is removed when the engine is running the ECU fails safe and switches on the fan, which runs even if the sensor is plugged back in. Looks like the problem is a dodgy connection making intermittent contact. Thanks for everyone’s help.
Steve

[Ethel]

Would an open contact not show on the gauge - though I suppose if it was only momentary?

 

The Mems supplies the coolant sensor from 15 with a pink/green wire and has a shared -ve return with the TPS, MAP & air temp sensors, pink/black at 13 - if you don't have the wiring diagram.

[NLinPEN]

A strange one this, the fan starts up before the engine gets to temperature but the temp gauge works as it should and the sensor appears to change resistance with temperature as per other posts. I’ve also checked the wiring and can’t see any chafing. The fan runs continuously until you switch the engine off again.
I thought that the ECU and gauge took their reading from the same temperature sensor on the thermostat body but I don’t understand why the gauge would read just above the minimum when the fan switches on, whilst also going on to read normal operating temperature once the engine warms up.
Any ideas?
Thanks, Steve

Is your car an MPI or SPI? On the SPI there is a separate switch that controls the fan. It is located at the bottom of the radiator.

[Ledlights]

Thanks, the car is a late mpi mini 40 so I understand the fan is controlled by the ECU.

[Ledlights]

Looks like I have resolved this by tightening the connector pins inside the plug. As above, any temporary disconnection triggers the fan.
Thanks for the help,
Steve