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Hey everyone,

My truck wont switch from rear to front tanks.
Wheni push on the switch nothing happends, the rear is full and the front is pretty low so i should be able to see the gauge move to low fuel.

I was wondering id there is a way to check the switch itself or the harnest with the wires so i can elimintae wether its the switch or not.

Also is there a way to check the slector valve as well.

I dont have test light but i do have a multimeter.

Pls describe in details


Thanks all
 

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Hopefully this will be of some help. Right out of the service manual:

Tank Selector Valve (Diesel Only) Component Testing Procedure

On the Selector Valve Connector, the terminals are:
Pin 1: Not used
Pin 2: 789 (BR/W)
Pin 3: 786 (R)
Pin 4: 673 (DB/Y)
Pin 5: 29 (Y/W)
Pin 6: 675 (Y/LB)

To Test the Rear Tank Circuit:
Briefly Apply 12V Power to Terminals 789 (BR/W) (+) and 786 (R) (-)
Connect Self-Powered Test Lamp or Ohmmeter to Terminals 29 (Y/W) and 675 (Y/LB): A good Switch will indicate Closed Circuit
Connect Self-Powered Test Lamp or Ohmmeter to Terminals 29 (Y/W) and 673 (DB/Y): A good Switch will indicate Open Circuit

To Test the Front Tank Circuit:
Briefly Apply 12V Power to Terminals 786 (R) (+) and 789 (BR/W) (-)
Connect Self-Powered Test Lamp or Ohmmeter to Terminals 29 (Y/W) and 675 (Y/LB): A good Switch will indicate Open Circuit
Connect Self-Powered Test Lamp or Ohmmeter to Terminals 29 (Y/W) and 673 (DB/Y): A good Switch will indicate Closed Circuit

Check that the source and return valve transfer between front and rear positions. NOTE: A brief “zip” sound can be heard when the valve transfers.
Cheers!
 

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Additionally, you could simply disconnect the fuel fittings leaving the electrical connector in place and look down each inlet/outlet while someone flips the switch to see if it's actuating properly.
 
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