Need help - can you tell me what this is?

[kngslb]

Hi All,

I just joined the 73-87ChevyTrucks forum.  I finished up my 72 Chevelle restoration this summer and got an old truck to work on.

I have an 82 GMC 2WD shortbox that I am starting to fix up. It is decent shape but electrical is a absolute mess.  It looks like at one point someone took the 6cyl out and cut some of the under the hood wires when doing so. They then put a 350 in and reconnected the cut wires with a combination of yellow house wire nuts and butt crimp connectors without knowing how to crimp. In addition to the that there was an aftermarket tach, aftermarket radio, and aftermarket gauges installed in the cab. Under the dash the wiring is also a disaster. I can't believe someone would butcher the wiring this bad as it is unsafe. Almost all of the their connections fell apart when I checked them.

Needless to say I have removed the gauges, radio, and tach and am methodically working through the wiring to put it back the way it should be. I am taking my time and soldering and heatshrinking the connections back together to make sure everything is safe and correct.

I was going to go with new harnesses until I saw the price of them. I then got a set of schematics off the internet and have a Haynes manual and am making decent progress fixing things.

There is what looks to be a electrically controlled vacuum valve mounted behind the brake booster. The wire for this is cut of course so there is no connection. The Haynes manual does not show what it is. I attached a picture of it. Can anyone let me know what this is?

Thanks for the help and I need to get a good GM factory manual off EBAY as the Haynes manual is not real complete.

I am sure I will have more questions before the wiring issues are corrected and ironed out.



 

[hatzie]

That's a GM # 14032087 AC Delco #212-331 TCC vacuum switch for the TH350C transmission.

To plumb it properly you'll need some vacuum hose and a GM # 14020691 AC Delco # 214-479 vacuum delay check valve between the switch and manifold vacuum.

[kngslb]

Thanks for the reply hatzie.

I following what you are saying on the vacuum connection to the intake manifold and thanks a lot of the part numbers.  That will be a big help.

I am assuming the electrical connections are 12V from the fuse box to feed the switch and the output of the switch goes down to a solenoid/switch on the transmission?

[hatzie]

Look on the upper left pane of PDF page 14.  The TH350C was RPO MV4 the sub harness diagram is on that page.  This sub-harness is the same in 82 & 83.
http://www.mediafire.com/view/1xqopb7dx8ydmsy/ST386_83_1983_GM_Wiring_Manual_CK_P_G_10_to_30_and_ST.pdf

The 1982 wiring diagrams are in the back of the service manual.  MV4 is on page 1359 but the 83 wiring diagrams scanned a little clearer.
http://www.mediafire.com/view/6ujcclrrb4gaggf/X8232_1982_GMC_CKGP_Light_Duty_Truck_Service_Manual.pdf

[kngslb]

Thank you very much for the help.  That answered my questions. I really appreciate it.