Need help with fuel tank selector switch wiring

[MSN Member]

From: Idontcare2
Sent: 3/19/2004

I replaced a bad fuel tank selector switch in my 88 Chevy Chieftain.  When I pulled the old one out of the dash it completey fell apart and thus I lost track of how the wiring went.  I have it wired in however it is backwards....I mean the tanks do not coordinate with the switch.  I was hoping someone that has a wiring schematic could look it up for me and let me know the setup.

The switch has five blades on the back side.  Two at the top and three at the bottom.  All sit horizantal.  Obviously, five wires to deal with.  Red, Yellow, Purple, Pink, and I belive Blue.  I don't want to start switching them around without knowing how they should go in fear of causing more harm. Any help is appreciated!!!!!

[DaveVA78Chieftain]

Sent: 3/19/2004

No matter what year of rig you have, this is one of those areas where almost no information exists to use.  Least wise, none that I have seen.  So, ....

1.  The actual selector valve selects one tank (say main) when 12VDC is NOT applied to the electrical terminal on it and the other tank (that would be AUX in this example) when 12VDC is applied to the terminal.  Now, since it is nothing more than an ON/OFF situation, that would mean the 2 terminals on the top of your dash switch are for the actual valve.  Being nothing more than a switch, it should not matter which wire goes to which of those 2 terminals.  One of the wires would have a constant 12VDC on it WHEN the ignotion switch is on.  The other wire would go to the valve.  You may have to do voltage/continuity checks to establish which wires are which.

2.  The 3 terminals on the bottom of the switch are for the fuel gauge.   The 2 outer ones will go to the sending units in the tank.  The center one would go to your gauge.  You simply may have to track them down.  Actually, you only really need to know which one goes to the fuel gauge.  The other 2 (outer ones) can be swapped if you have a reversed tank indication.
Hope this ascii art works:

_________       Dash Switch
| Main        |_______|     |
|_Tank____|           | \   |                        _______        ___________
                            | .\__|______________| Fuel  |______| regulator |_______ 12VDC
_________             | .   |                       | Gauge |      |           |
| Aux     |_________| .   |     
| Tank    |             | .   |
                           | .   |
                           | .   |
                           | .   |
                           | \   |                     __________
                         |  \__|______________| Selector |
                           |     |                      | Valve    |
12VDC     ________|     |
                          |     |

Switch shown in main with no power applied to the valve.  When in Aux, power is provided to the valve.
Thats the basic setup, Some (like mine) also incorporate a relay in the valve circuit to reduce current flow through the switch.

Dave

[MSN Member]

From: Idontcare2
Sent: 3/20/2004 

Dave,

Thanks for the information.  I was able to get it working thanks to your post(s) and a voltage meter.  I also called winnebago and had them fax a hand written diagram.  But of course they had completely different wire colors than my rig.  So much for the simple answer approach.  Thanks again

Shawn