Vacuum Diagram
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Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
If you have a single line for the modulator it runs from the modulator to the vacuum tree on the intake manifold.
If you have two lines to the modulator, the line at the back end of the modulator still goes to manifold vacuum. The second line of the modulator (the one that hooks up closest to the transmission) goes to a fitting located on the firewall. This fitting (called a loop) has two hoses hooked to it. The one goes to the trans. modulator, the other t's into a vacuum line that goes from the EGR valve to the temp controlled vacuum switch located on the intake manifold.
If you have two lines to the modulator, the line at the back end of the modulator still goes to manifold vacuum. The second line of the modulator (the one that hooks up closest to the transmission) goes to a fitting located on the firewall. This fitting (called a loop) has two hoses hooked to it. The one goes to the trans. modulator, the other t's into a vacuum line that goes from the EGR valve to the temp controlled vacuum switch located on the intake manifold.
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Joined: Aug 2010
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If you have a single line for the modulator it runs from the modulator to the vacuum tree on the intake manifold.
If you have two lines to the modulator, the line at the back end of the modulator still goes to manifold vacuum. The second line of the modulator (the one that hooks up closest to the transmission) goes to a fitting located on the firewall. This fitting (called a loop) has two hoses hooked to it. The one goes to the trans. modulator, the other t's into a vacuum line that goes from the EGR valve to the temp controlled vacuum switch located on the intake manifold.
If you have two lines to the modulator, the line at the back end of the modulator still goes to manifold vacuum. The second line of the modulator (the one that hooks up closest to the transmission) goes to a fitting located on the firewall. This fitting (called a loop) has two hoses hooked to it. The one goes to the trans. modulator, the other t's into a vacuum line that goes from the EGR valve to the temp controlled vacuum switch located on the intake manifold.
followed the tubes down to the transmission, there is 2 vacuum lines on/behind the motor, passenger side, right behind the valve covers.
on both ends, by the motor and down by the transmission, one of the lines is blocked off. im assuming that its okay since i dont see any thing else on the transmission or firewall for it to connect to. i did see the 'tree' sticking out of the intake manifold, should all the tube holes that dont have a vacuum line running from it be plugged up? there is one line from the tree, and i think that a couple of them are open uncapped?
transmission modulator... the vacuum line to this was disconnected. i reconnected to the modulator, and tried to see if it would shift and stay running, no luck. i dont believe that its getting a tight seal on the modulator, or can the modulator be bad enough to where it could be affecting my shifting out of park into reverse/drive?
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
If the modulator is disconnected/bad the trans will engage very roughly and won't want to upshift untill very high road speed and when/if it does shift it will be very harsh.
One telltale symptom of a bad modulator is if trans fluid drips out of the vacuum line when disconected at the modulator.
All unused branches on the vacuum tree need to be capped.
Sounds like your trans originally had the two lines but has been changed to a single line.
Just be sure the line is a snug fit at both the modulator and the intake manifold.
One telltale symptom of a bad modulator is if trans fluid drips out of the vacuum line when disconected at the modulator.
All unused branches on the vacuum tree need to be capped.
Sounds like your trans originally had the two lines but has been changed to a single line.
Just be sure the line is a snug fit at both the modulator and the intake manifold.
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