dual tanks -- need advice

[mdj3316]

The dual tank selector in my folks' 1985 Chevy has stopped working. The only fuse I can locate [in the main fuse block] is OK, the dashboard switch is apparently only removable from behind, I can't get behind the dash enough to either remove the clip holding the switch or get the wires loose [at least, not with any hope of getting them back in the switch block], and from the looks of the nuts attaching the cover over the main switching unit underneath [and what I can see of the unit itself], any attempt at disassemby will probably break something.

I would really hate to replace the main unit and then find out it is a bad switch -- especially since I still won't be able to figure out how to get the switch out.

Any bets on whether the problem is at the dash or under the bed?

How do I get the switch out, short of breaking it or cutting a hole in the dash?

Thanks!

[Mike76251]

99% of the time it seems to be the switch on the dash (according to very excellent local Chevy parts guys)
I did mine six or so years ago and a new switch fixed it.
If I remember right......I took off the A/C duct to reach the back of the switch. Wasn't really that much trouble.

[mdj3316]

Thanks for the advice. However, I took off the plastic heat / AC duct that runs below it, and while that allows me to get close enough to probably try the "grab and yank" method on the wires, I can't get to the top of the clip to push it up.

[Mike76251]

Darn.........I missed something........Welcome to the site BTW!!

I have pretty small arms I guess.
I don't remember having any trouble removing the clip.
Could you push it up with a long punch maybe?

Good luck whatever happens.
Mike

[swervin ervin]

If/when you get the dash switch out, you can make a horse shoe wire to make contact at the different terminals of the plug. I'm not sure of the exact ones needed to move the selector valve, but it shouldn't be too hard to figure out. Anyway, if the switch is bad, doing this will tell you pretty quick, when you see the gauge move, or hear the valve switch over.

But after saying all this, my money is on the selector valve. One sure fire way of telling which one it is, just replace the dash switch first. It's around 8 bucks at the dealer. Won't hurt to replace it anyway. If this don't fix it, then you can replace the selector valve.

But before removing too much stuff, check the wiring going to the switch. Make sure it's not burned in two. For some strange reason, GM thought it would be a good idea to run the wiring across the frame, right above the exhaust. Bad location for wires to go.

[mike reeh]

yeah my money is on the valve, too...

If its that hard to get the switch out, then go underneath and unhook the pigtail at the selector valve and use a test light to check if the switch is working. you'll obviously need a helper to work the switch, and a wiring diagram if you dont know what to check. But if you ground the test light and just check every connector, it should be easy enough

mike

[79BIG10]

On your 85 you would have 1 green wire going to the tank selector valve. Flip the switch to the rt. side and take a test light to the end of the green wire. Should have no power. Then flip the switch to the left side. You should have power on the light. If not you either have a bad connection at the firewall, a bad switch, or the wire at the fuse panel as become disconencted. If the light comes on then you have a bad valve.