4g61t.org

I stumbled across this and its been puzzling me as to what it is. Any ideas on what it is and what it does?

Idle switch. Tells the ECU that the throttle plate is shut.

Thanks, looks like pin #14, mine was cut off when i got the harness.

that is used if you have AC... its the high idle for when the ac is turned on.. if no ac u can remove it.




Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

Interesting, I thought this^ I've even adjusted my idle with it just tinkering around, didn't know it was related to A/C.

I think I remember seeing something in link about it too, there was an option for "idle stop switch" I think it is needed unless disabled properly.

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89 Mirage Billet 20g 63t 12.4@120 417whp 400wtq @ English Racing.
89 Colt GT E316g
06 Silverado SS
07 ZX6R

You sure about that? Every 1G DSM comes with that switch, A/C or not. Link and Werewolf go to great lengths to emulate it in their software, and it's even in the ecmlink wiki.

http://www.ecmtuning.com/wiki/idlesurge

It uses the idle switch to know exactly when the throttle plate is closed, so the ecu can begin using the ISC subroutines dedicated to idle.

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Early 2000's: 1992 Summit sedan - 14.1 @ 100.9mph w/ 155/80 13s
2012: 1989 Dodge Colt GT Turbo - 14.9 @ 100mph, 10psi/s16G

As stated above, without an idle switch there will be all kinds of idle related and driveability type concerns. You need to have that hooked up, for any form of engine management, especially with factory 1G ECU's. You can see test it with a test light grounded/clipped to the sensor male end (disconnect the wire from the male end first ) and hooking up the other end to BAT +. If it lights, you have a proper ground. You can crack open the throttle and see at which point it begins to operate as well. Just to make sure you still have a good contact point. Mostly it was the wiring that would get corroded or the large rubber boot would deteriorate and the wire would fall off, weak terminal retension. Easy enough to forget when re-installing parts recently removed parts, or to knock loose.

NINJA EDIT - Also a good idea to have a ground strap from the intake manifold to the firewall. This provides a proper ground return for the switch. Most time people leave out the little metal strap/tab that used to go from the elbow to the TB itself, and they would not get a ground back to the engine and in return to the firewall.

Jeez guys, way to rub it in

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89 Mirage Billet 20g 63t 12.4@120 417whp 400wtq @ English Racing.
89 Colt GT E316g
06 Silverado SS
07 ZX6R

Haha, you have it all wrong officer!

I certainly don't mind being corrected, as I routinely find out over at "www.galantvr4.org", and here too.

I think if we were really hard on him, we'd mention getting vetted into a site like Neigh Boor (once upon a time). They're strict.

Check the tps sensor. If it has 4 wires going I to it the it has the idle switch build into it.

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05 wrx wagon
99 Benz ML 320
91 eagle summit swapped - 6/4 bolt combo
94 Audi s4 - sold
88 Eagle Vista Turbo LX sedan, RIP

Newer style sensors had that ? Pre-95 ? Post 95 ?

This is where a wack load of us have experience in certain year ranges and have to come to a concensus!

Just some more info on it I found..

1G DSM Idle Speed Switch
This little switch sits on top of the throttle body and is closed when the throttle plate is shut while off throttle. This lets the ECU know that the car should be idling and setups up a different air/fuel mixture for best economy. Some symptoms can be a loss of fuel mileage and slow warm up. Go out and test your switch with a multi-meter and if it is bad replace it today!

The switch also acts as a throttle plate stop so you don't stress the throttle body if you slip off the gas pedal which causes the throttle plate to slam shut.

http://www.machv.com/1gdsmidspsw.html

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89 Mirage Billet 20g 63t 12.4@120 417whp 400wtq @ English Racing.
89 Colt GT E316g
06 Silverado SS
07 ZX6R

Yes newer style TPS had the idle switch built into it; 2G dsm / 4G csm have them. The sensor are physically the same. Except for that the new one has 4 wires not 3. You can run a 4 wire TPS with a 3 wire plug and the old Idle switch too.

Its not uncommon for DSMers to swap to a 2G style TPS. Cleans up the engine bay some.

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05 wrx wagon
99 Benz ML 320
91 eagle summit swapped - 6/4 bolt combo
94 Audi s4 - sold
88 Eagle Vista Turbo LX sedan, RIP