I'm working on getting my truck running that has been sitting for a number of years. In the process of checking things out, I've discovered that the previous owner changed some of the vacuum routing and disconnected some of the lines.
I think I can get things put back by following the VECI sticker on the top of the radiator support under the hood, but some of the abbreviations are cryptic to me. I have the Haynes manual, which has been helpful in a lot of ways, but not with definitions. Maybe someone here can help.

I have some hard plastic vacuum lines that run to/from a group of what look like three small solenoids. The wiring to these runs to the EEC unit. So I take it these are vacuum circuits controlled by the computer. Indeed the diagram labels each as SOLV ___.
SOLV EGR is apparently Solenoid Valve Exhaust Gas Recirculation and the green line runs from this to the EGR valve both on the schematic and physically in the truck. No problem! The other two seem to be a linked pair and are shown in the diagram to lead to opposite sides of the ACV. These two are labeled SOLV TAD (a black line) and SOLV TAB (a pink line). These two are disconnected.

My questions:

• What is ACV?
• What is TAB?
• What is TAD?

For ACV my guess would be ACcessory Vacuum and would mean the vacuum tree sticking out from the intake manifold beneath/behind the carburator, but I'd rather ask than guess. I haven't even got a guess about the others.

While we're at it, what are these three?

• VRDV
• A/CL over DV
• P/D MTR

These all appear to be hooked up, but I'm still curious what the abbreviations stand for. Once I know what this stuff is, I'll be better able to evaluate whether its hooked up CORRECTLY.

While I'm here, I want to say I think this forum is great! I can't think of any other way I could access the kind and amount of knowledge and experience that is represented here. To the people who run this, Thanx

 

My site is definitely not flashy, but it has some useful data. Go to emissions, there's a glossary of terms I've scanned in.

www.tetraruby300.freewebsitehosting.com

Sorry about the popups. It's been slow going with the development. Hope it helps.


Keep it in-line!

 

Air Control Valve (the heat riser flapper)
Thermactor Air Bypass (the big plastic valve that controls the air from the smog pump)
Thermactor Air Diverter (the other part of the above valve)
Vacuum Regulator Delay Valve (a calibrated restriction)
Air Cleaner Delay Valve

I don't know what P/D Motor is, but it's a vacuum motor like the one that controls the heat riser or the fresh air blend door for the ventilation.

 

Thank you both for the information. Knowing what the abbreviations stand for allowed me to find the section in Haynes about the thermactor and read what those lines go and what they are for. Tomorrow I can check out the truck and see if any of the thermactor equipment still exists in the engine compartment or not. Hopefully the previous owner didn't just start ripping stuff out! Perhaps I'll get lucky enough to find that I just need to replace the hoses that connect those lines to the Air Control Valve. I'm glad I asked rather than going with my guess - since my guess was WRONG!

tetraruby, I'll take useful data over flashy every day of the week. Thanks.

 

Take a look thru the GP Pics album in my signature link.

 

I like both the site and the "Dirty Old Truck." I couldn't help hearing Johnny Cash singing the notes section in my head, though.... I doubt my truck will ever be so customized. Keep up the good work, Steve.

 

Well, the thermactor is gone. So, I have no place to connect the TAB vacuum line and the TAD vacuum line. Is it ok to cap them, or will that mess with my EEC unit to the point of eventually damaging it?

Emissions testing in my area is pretty reasonable. If you pass the gas cap and tailpipe tests, you pass. So, that is less of a concern to me than somehow causing damage to my truck. If missing equipment will overload the computer, then I'll have to pursue replacing the missing equipment. If missing that equipment causes me to fail the tailpipe test, again, I'll have to pursue replacing it.

On the other hand, if neither of those is the case, I'd rather spend my TE&M on other pusuits. Advice on this would be appreciated.