I apologize for the delay. The front wheel engagement vacuum controlled, and when you have the front wheel lights flashing it is indicating that the front wheels are partially engaged.This is almost always caused by a faulty freewheel clutch solenoid pack. This is a very common failure point on these trucks.You will want to go over all of your vacuum lines carefully looking for any tears or disconnected hoses that could also cause this condition. This includes taking the lower skid plates off and checking both hoses on the actuator diaphragm mounted on the axle case.If all looks well, you will be interested in replacing your free wheel clutch solenoid. This part is located on the passenger side frame rail, just below the air filter housing. It is a bracket with two solenoids mounted to it, several hoses and two electrical connectors.The free wheel clutch solenoid packs vary in price by year, but run around $200.
Just make sure to take a photo of all the connections before removing so you can easily replace them to their correct locations.
how much does it cost to replace it any idea in uk?
You would have to use a currency convertor Online.
Generally parts are slightly higher in the UK, but labor is the same.
I would say the take the equivalent of $350USD into a currency convertor online and that should give you a high estimate.
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