Help with identifying something on fuse box

[motornut]

always a draw?...wonder how many batteries died with that,
or guys trying to figure out the draw

[hatzie]

The valve should never ever be powered with the ignition off.
My guess is there's supposed to be a delay timer of some sort in this relay. A bit overcomplicated and a reliability issue.

You could accomplish the same thing using a 5 pin SPDT relay.

Bosch Mini ISO pinout would be.
Coil - Pin 85 Black 150
Coil + Pin 86 Purple 6 (Ignition Start off the Neutral Safety Switch)
Common Pin 30 Dark Green out to switch.
Norm Open Pin 87 Orange Battery
Norm Close Pin 87a Pink/BLK 139 (Ignition Power)

[8lugnutz]

With the testing I did, the relay stayed engaged. However, with that said, it was a short test. The GM Parts WIKI shows the title of this part to be:

CONTROL, Fuel TK MTR SEL SW ELEC Timer http://www.gmpartswiki.com/getpage?pageid=93626

I interpret that to be "Fuel Tank Motor Selector Switch Electrical Timer". Based on this new information, my theory now is that the relay does not remain permanently engaged by constant power (as I previously stated based on my short test), but rather is only engaged initially by the orange wire when the key switch is in the START position, and once the timer has expired, returns the relay to "normal" operation by powering to the tank selector switch by the PNK/BLK when the key switch in the RUN position. This would result in the power being removed from the circuit completely once the key switch is turned to the OFF position, therefore preventing battery drain.

I will pull the relay and do a bench test on it and see if I can figure out how long it remains engaged and let you all know if my theory is correct. Then I just might eat some crow with a smile, and update my diagram

[8lugnutz]

Well, so far the relay has been powered up on the bench for over 20 minutes and the timer (if there is one) hasn't expired and switched back to the PNK/BLK power source. Will keep watch over it and see what happens.

[8lugnutz]

I left the relay connected and it still hadn't switched over to the PNK/BLK after an hour. I don't see this being a timer relay.

Maybe Keith Seymore can ask one of his buddies at the factory how it operates, because I am at a loss here after doing these tests.

[Sabaka454]

Looking at the factory wiring diagram they do not show the relay. Looking through the manual they don't talk about it either.

[8lugnutz]

Agreed Sabaka454, that's what lead me to where I am today. As you said, neither the wiring diagram or any manual I have seen mentions this relay or alternate wiring, but all my research has revealed it was a one year configuration for the 1980 year model. This has been confirmed not only by talking to a couple of parts guys at different dealerships, but also by other forum members. It's definitely odd!

[Sabaka454]

You have me curious enough that if I had an 80 still I would check and draw up the schematic but I sold that one too long ago.

[8lugnutz]

I'd love to see some more '80 owners post their findings too. It's quite unique for these trucks that's for certain!

[hatzie]

This might've been dealer installed for a specific complaint or a 1/4 or 1/2 year change sheet that didn't get into the service literature. You might find mention of it in the Chevrolet Service News magazines or GMC / Chevrolet TSB sheets...

I would suggest the OP get help from the mods to crosspost the meat-n-potatoes of this to a locked thread with a link back to this one in the 73-87 electrical FAQ so it can be found.

I only have a smattering of the Chevrolet Service News magazines and TSB sheets from 73-78. I'll eventually scan and post the ones I have so they don't disappear entirely.

[8lugnutz]

Ok guys, mystery solved. I ordered a wiring diagram off of eBay.



Here is the page that identifies the relay:



And the detail:



There is a timer that expires 30 mins (+/- 10 mins) after the ignition is cut off, so no constant draw.

[motornut]

gee, cool
wondering if/could that timer relay be used with the headlights wired to stay on or dome light?
after turning the truck off like newer trucks

[8lugnutz]

I bet you could do that it shouldn't be too hard, but I don't see the sense in leaving a dome light or headlights on for 30 mins (+/- 10 mins). There are other relays out there that may serve this purpose better.

[Sabaka454]

Good find! Too bad it still doesn't make any sense though. I fail to see the purpose of it which they probably did as well and the reason it was omitted I'm assuming .

[Timj]

I have the same truck even with the same build month. I will tell you that extra part on the side of the fuse panel is for a timer relay for the fuel tanks. Only installed on the 1980 model year. This truck automatically defaults to the right side tank. The timer relay is there to shut the power off when you get out of the truck and turn the key off so it doesn't drain your battery. So if that relay is missing your left tank most likely doesn't work. I had the same problem. Mine was missing when I bought my truck and I had a hard time even finding a picture of the relay considering its not available through most parts houses. I lucked out and found one in a truck that was being parted out and it works great. They sell them on eBay for 40 to 60 bucks new old stock. The part number is 14014527. Punch that in on eBay and you will find it. here is a picture.

[hatzie]

Originally Posted by Timj

I have the same truck even with the same build month. I will tell you that extra part on the side of the fuse panel is for a timer relay for the fuel tanks. Only installed on the 1980 model year. This truck automatically defaults to the right side tank. The timer relay is there to shut the power off when you get out of the truck and turn the key off so it doesn't drain your battery. So if that relay is missing your left tank most likely doesn't work. I had the same problem. Mine was missing when I bought my truck and I had a hard time even finding a picture of the relay considering its not available through most parts houses. I lucked out and found one in a truck that was being parted out and it works great. They sell them on eBay for 40 to 60 bucks new old stock. The part number is 14014527. Punch that in on eBay and you will find it. Attachment 1667856 here is a picture.

The best option is the GM relay but as they get closer to unobtainium other options are available.

Hella makes a Timer relay with the standardized five terminal automotive Mini ISO form factor. You'll have to migrate from the proprietary GM relay socket to a Bosch Mini ISO socket to use one. Both sockets use Packard 56 terminals so it'd be a matter of moving the relay socket terminals from the GM socket to the Bosch ISO socket.
http://hellahd.com/index.php/default...cs-product-12/

The Delay Off version is the one you want. https://www.amazon.com/HELLA-9961521.../dp/B003C508XO

[44SAA]

My ‘80 has a battery drain since I purchased. In short, will simply removing p/n 14014527 stop the drain? I’m convinced it’s the source of my drain and I am okay not using the auxiliary tank. Thank you

[8lugnutz]

Originally Posted by 44SAA

My ‘80 has a battery drain since I purchased. In short, will simply removing p/n 14014527 stop the drain? I’m convinced it’s the source of my drain and I am okay not using the auxiliary tank. Thank you

You can certainly try it and see. It’s been a minute since I’ve had my brain wrapped around the schematic, but I think it only applied power to the relay if the selector switch was in the position that required the actuator to stay engaged. If it wasn’t required it wasn’t powered if I recall correctly. Pulling it shouldn’t affect the main tank or operation of the vehicle.
Good luck!

Rick

[44SAA]

Thanks Nutz- I’m gonna yank it out and test. I’ll report my findings. For the last 10yrs I’ve had to disconnect my bat after driving- absolute beating….

[44SAA]

May have solved the bat drain. The ground wire connecting to the bus bar to the relay was not connected. I simply removed the ground wire from the bus bar. Fingers crossed..