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Category: Car
Satisfied Customers: 3498
Experience:  Manager/co-owner at Autotronic
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Vauxhall astra i have a vauxhall 1998 astra mk4 1.6 16v and

Customer Question

i have a vauxhall 1998 astra mk4 1.6 16v and the cooling fan runs all the time i have put a new tep senser on and it still keeps running i have put on a cooling fan ecu / relay that under the n/s/f wing but its still on
Submitted: 6 years ago.
Category: Car
Expert:  nabilc replied 6 years ago.
Hello and welcome to JA!!!

I'm Billy and i will help you with this.

The cooling fans in your vehicle are more related to the A/C system, than they are related to engine management and temperature sensor.
They take their power supply from specific relays, i will post the relevant wiring diagram, in which the engine coolant blower motor (cooling fans), are marked M6 I and M6 II.
check their respective relays:

And here is the legend:

Should you need more help, i will be more than glad to provide it.

Customer: replied 6 years ago.
i have looked at all the relays and they are all ok and have had a probe on the loom and thats all ok
Customer: replied 6 years ago.
Relist: Inaccurate answer.
Expert:  nabilc replied 6 years ago.
Hello again,

If you are SURE that relays are good (all the K12s), the cooling fan gets the positive from the relay (considering that there is no short to Battery positive along the wires, as you checked the loom). Then you have positive coming from the A35 (engine control module), which is triggering the K256 relay (WOT: wide open throttle relay), and then triggering the cooling fans. To make sure that this is the problem, you need to check if you have B- or negative on the sw bl (black/blue) wire coming from A35 (ECM) to the K256. If you do have then it is triggered by the engine control module, which needs reprograming or replacement.
PS: i can assure that (according to diagram) only if all wires and relays are good!