Author Topic: Dual Tank Dashboard Switch 84 K30  (Read 10541 times)

Offline enaberif

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #15 on: March 25, 2015, 06:57:28 AM »
Hatzie there is also a push/pull style that is very uncommon found in the 73-74 trucks possibly 75. Looks like a headlight switch.

Offline LTZ C20

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #16 on: March 25, 2015, 09:46:42 AM »
HATZIE, you should put all of this information into a post in the tech section. I will be looking for this info when I put my TBI back to working dual tanks.
« Last Edit: June 20, 2015, 01:41:29 PM by bd »
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Offline Takilma

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #17 on: March 26, 2015, 12:10:57 AM »
Hatzie,
Good stuff, thanx. I'm saving the link to the GM diagrams. I think you've pretty much put this topic to bed.

Offline hatzie

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #18 on: March 26, 2015, 01:03:34 AM »
Hatzie there is also a push/pull style that is very uncommon found in the 73-74 trucks possibly 75. Looks like a headlight switch.

There was a cable operated valve in the 73 & 74 trucks.  Not much info on these in the service literature and parts are near non-existent.  I believe the cable valve system had a completely separated dash mounted SPDT switch to route the senders to the gauge.  The gauge didn't follow the enabled tank.

1980 had a time delay relay to keep the valve energized with the starter.
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline hatzie

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #19 on: April 02, 2015, 12:23:32 PM »
HATZIE, you sh ok uld put all of this information into a post in the tech section. I will be looking for this info when I put my TBI back to working dual tanks.

TBI fuel pumps run off the same Green wires that run the valve.  It's actually pretty clever that they didn't have to switch the fuel pumps any further.  The fuel sender and fuel pump share a ground that runs through the liquid tight grommet in the sender to the frame along with the fuel pump power wire and sender wire that run to the valve.   
They shut off the not selected fuel pump as follows...  When the LH tank is selected the RH fuel pump has two grounds.  When the RH tank is selected the LH fuel pump has two grounds.  You need power and ground to run the fuel pump two grounds will just shut it off.

GM did a poor job of making the 1987 RV series wiring diagrams readable.  They're very difficult to follow and not miss things... like the Hot-Start fuel pump relay system controlled by what passed for an ECM in 1987.
Look over the 1988 -1991 RV wiring diagrams but keep in mind they also seem to be missing the fuel pump relays...  Maybe that's a 1987 only thing but I doubt it.
1987 TBI is where the MOTOR year-specific wiring diagrams shine.  Pages from that manual, that include the hot start relay etc, are posted here...   http://forum.73-87chevytrucks.com/smforum/index.php?topic=9072.msg198713#msg198713
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline LTZ C20

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #20 on: April 02, 2015, 02:06:10 PM »
Yea that info will be needed when I get around to making both tanks work again.
LTZ Cheyenne C20

Offline enaberif

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #21 on: July 19, 2015, 11:51:16 PM »
found this courtesy of hatzie


Thank God for this layout as I'm going to need it RIGHT quick. Quick question regarding this... I should be able to ohm out the pins on the switch to get a reading from tank? Meaning if the sender is right in the tank then I should be able to get the 0-90 ohm reading correct?

Offline hatzie

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Re: Dual Tank Dashboard Switch 84 K30
« Reply #22 on: January 20, 2016, 07:36:51 PM »
found this courtesy of hatzie


Thank God for this layout as I'm going to need it RIGHT quick. Quick question regarding this... I should be able to ohm out the pins on the switch to get a reading from tank? Meaning if the sender is right in the tank then I should be able to get the 0-90 ohm reading correct?
You should be able to test the senders from the dash switch plug to a good ground.

Sent from my SM-P605V using Tapatalk
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC