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What is this little valve up by my firewall?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer_Boy, Apr 6, 2001.

  1. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    What this valve/vacuum hose on the firewall. I guess its time for another retarded question. '82 K5 w/350 and newer 700R4 (? on the tranny year, the guy before changed everything and the tranny has one of the big GM stickers with the bar code and big letters they but on there new stuff on the side of the case). Anyways, near the wiper is some electrical wires that lead into a valve which has vac line comming out with a little light blue and black cylinder inline of the hose. What is it? It isnt hooked up, where does go? My vac routing is basically a copy of 1969-75, if that helps for hooking it up again.

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  2. bablazer73

    bablazer73 1/2 ton status

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    If the valve is on the passenger side of the firewall, above the right valve cover, it's part of the E.S.C. (electronic spark control) it was used to electrically control the vacume to the distributer. If you are not using that or the computer that went with it, scrap it!

    your right. I don't understand the jeep thing!
     
  3. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    This little fellow is over by the the brake booster on the driver's side. I don't know whats left of the ESC. We had the motor swapped on our '81 with a '78 350 and they hooked it up to the carb. The '78 carb has the older divorced choke where as mine has the electric .
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  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Up to the top for some more ideas on what i should do, thanks

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  5. Ditchdigger

    Ditchdigger Registered Member

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    Hey Blazer Boy, If were talking about the same thing, I have it on my passenger side firewall above valve cover about a foot', Its some type of solenoid that measures vacuum from the main Intake vacuum rear of manifold, and has one hookup with two wires and they go into the main harness branch But, I haven't traced them yet!
    One more thing, I have an 84 Non-ECM with a TH-350 and Q-jet. If that helps!!!

    If it ain't Intimidating / It ain't a Chevy!
     
  6. northgate

    northgate Registered Member

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    It's the vacuum switch for the torque converter clutch (TCC) solenoid. When your engine has the correct manifold pressure (vacuum), the switch closes and will allow the solenoid to actuate the clutch. Under load (low vacuum), it opens and dis-engages the clutch. If you hook it back up correctly you'll probably get another mile or two to the gallon on gas. Just need a manifold vacuum source is all.
     
  7. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    WOW! Thank you! That makes sense because when I look on every vac diagram all the ports of the carb are accounted for, so scratch that for a possibility. I just replaced some missing cruise parts and there's also a line going to a little ball over by the condensor those both go to the manifold vacuum, leaving one line capped and that line is the same size as that unhooked line. Thanks!

    I do have another one over by the passenger side that other people have mentioned. Is that part of the ESC unit?

    [​IMG]<P ID="edit"><FONT SIZE=-1>Edited by Blazer_Boy on 04/07/01 11:33 PM (server time).</FONT></P>
     

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