Adding Idle Up function to Auto Trans with Digifant

[r.e.wing_fc3s]

the 1986 vanagon protraining manual clearly shows that there were plans for an input to the idle control module from the auto trans selector. This was never put into production on any van i have seen. When it is cold <30f and i start the van and immediately put into reverse the idle dips to low, if i let things warm up for a minute or two its not as bad. So according to the diagram in the protraining the a/c compressor when engaged idles up the van, this circuit was to be shared with the auto trans selector. I no longer have a/c so the wire from the idle control unit to the compressor is just sitting there waiting to be repurposed. id like to try hooking this up to the reverse light circuit so that when reverse is engaged it sends power to the lights and also an idle up signal to the idle control module. Any reason i shouldn't try this?
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Reference Automotive: NW Washingtons Vanagon Specialist. (360)366-6965. referenceautomotive.com

[hdenter]

I'm no expert, but is seems like a good idea to me. My only thought would be if it pushes it up too high, the car might surge backwards.

Hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[danfromsyr]

it really can't push the idle up too high, only the predetermined amount to counter act a Load against the engine.

you can hook that AC input to a manual controlled switch
voila instant High Idle.. anytime you'd like.. can be handy at times.

you could find a place to tap into the pressure system of the AT fluid and use the pressure type switch that the PS pump uses to increase idle when that fluid is cold/thick.
but it wouldn't be necesarily dialed in the same (viscosities & set pressure etc) as the PS system is from the factory.

while I try not to run extra wires, it may be easier/more handy to hook it up manually.. or if electrical electronix work is your thing maybe hook it via a realy with Temperature feed.. kinda like the Diesel glow plug relay works. there's plenty of diagrams out there for those to understand it's functions to repurpose/manipulate to your needs. this would run a higher idle only when the engine is ist started when cold but not when hot.
would require a temp sensor in the coolant jacket.


Dan
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[r.e.wing_fc3s]

keeping with the simplest approach i found the splitting connector for the reverse lights in the wiring box. the old wire for the compressor reached all the way to the wiring box. i used a scotchlock connector on the single reverse light wire before the splitting connector and a spade terminal on a short length of wire from the scotchlock to the female spade on the a/c compressor wire. looks almost factory. i then tested the change in amperage while activating the p/s pressure switch vs. the ac compressor switch/reverse gear. my multimeter is a p.o.s. b.t.w. baseline current draw for idle air valve is 510-530 milliamp. w/ power steering 560-70 milliamp. air conditioning "mode" activated through auto selector reverse light switch. 590-610 milliamp. I then fired it up and immediately into reverse. no low idle. just ever so slightly above or at idle in park and neutral now.
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Reference Automotive: NW Washingtons Vanagon Specialist. (360)366-6965. referenceautomotive.com

[r39o]

The power steering also has the same function. Look for the wire. If you hit the stops it should drive the idle up. I think it is a ground active input.
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[r.e.wing_fc3s]

for sure . as i posted though, with a/c mode "on", the idle control unit boosts the current more then for the p.s. pressure switch "on"mode
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Reference Automotive: NW Washingtons Vanagon Specialist. (360)366-6965. referenceautomotive.com