fan sensor PROBLEM SOLVED !!!!!!!!!!!

[frankb]

Herb:

Speaking from the standpoint of the Mk4 with the RF harness, there should be +12v at the thermo switch terminal with the key in the "Run" position and the engine cold. If not, there is a problem in your "control" circuit. (See CFranks' comments above)

With the key in the "Run" position and the engine cold, there should be 0v at the dark blue wire in the fan connector.

Next, at the fuse block, check for voltage at the "Fan" fuse. There should be +12v on either side of the fuse (with the key either in "Off" or "Run"). If there is +12v on one side of the fuse, but not the other, the fuse is bad.

If both the above check OK, set the key in the "Run" position and jumper the wire on the fan thermo switch to the block. You should now have +12v at the dark blue wire at the fan connector and the fan should start. If not, check that the black wire at the fan connector is properly grounded. If all these check OK, the issue is in your relay or the fan dark blue wire from the fuse block to the fan.

Does this help?

The below relay diagram applies...

[herb fraser]

Herb:

Speaking from the standpoint of the Mk4 with the RF harness, there should be +12v at the thermo switch terminal with the key in the "Run" position and the engine cold. If not, there is a problem in your "control" circuit.

With the key in the "Run" position and the engine cold, there should be 0v at the dark blue wire in the fan connector.

Next, at the fuse block, check for voltage at the "Fan" fuse. There should be +12v on either side of the fuse (with the key either in "Off" or "Run"). If there is +12v on one side of the fuse, but not the other, the fuse is bad.

If both the above check OK, set the key in the "Run" position and jumper the wire on the fan thermo switch to the block. You should now have +12v at the dark blue wire at the fan connector and the fan should start. If not, check that the black wire at the fan connector is properly grounded. If all these check OK, the issue is in your relay or the fan dark blue wire from the fuse block to the fan.

Does this help?

Hi Thanks, it helps, but there is NO power on either side of the fuse at the fuse box
and no power at the black or blue line at the fan connector