2000 Jeep Grand Cherokee with 4.0L engine cooling fan will not engage

Car wiring question

t16 I just subscribed to ATS to be able to help my daughter who bought a 2000 Grand Cherokee from an auction. She said the price was pretty cheap and she thought she got a good deal because both inside and out of the car looks clean.However, after picking it up from the lot, it seems to run abnormally hot. I had the cooling system checked and it seems somebody already replaced it with new radiator and thermostat.

What they did not correct is the cooling fan won’t engage as soon as it gets hot. I think this problem is only in the wirings or some electrical components; can you guide me in the right solution? I will appreciate it very much.

Wiring diagram advice

Looking at the wiring diagram, your cooling fan has 2 wires: dark green wire which is your supply wire 12 volts and black pink wire which is your ground wire. Check the ground wire first by making sure that it is fasten tight and not corroded at the right hand headlamp area. The supply wire comes from a fan relay, which is located behind the bumper also in the right hand headlamp area.

You might have to remove the bumper to do this fan relay. Just make sure that with your key on, there is power going to the grey wire in the fan relay and when you reach the hot temperature, that dark green wire from the fan relay kicks in. Otherwise, you need to replace that.


It is preferable to use a wiring diagram when tracing your starting circuit, should you have any difficulty, ats can give you complete descriptions on the wirings.

When working with any electrical component, disconnect the battery negative terminal.

Whenever working under the dash panel, do not touch the yellow-taped wiring harness to avoid accidental deployment of the air bag which will activate even with the battery disconnected. Remember: you do this service at your own risk.

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