# Shift blocking

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> Source: https://en.wikipedia.org/wiki/Shift_blocking
> Source revision: 1329682049
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{{Short description|Automotive transmission feature}}
'''Shift blocking''' is a feature of [automobile](/source/automobile) [manual transmission](/source/manual_transmission)s added to improve fuel economy ratings in the [Corporate Average Fuel Economy](/source/Corporate_Average_Fuel_Economy) (CAFE) system by preventing a driver from switching from first gear to second or third as would be done normally. A solenoid prevents the shifter from engaging these gears, forcing the driver to shift from first to fourth gear. The solenoid is computer controlled, and will deactivate if the throttle is opened wide enough, or the car reaches speeds above those typical in city driving.

==Usage==
The skip shift feature was originally introduced in the [Chevrolet Corvette](/source/Chevrolet_Corvette) in the late 1980s,<ref name="allen"/> with the name CAGS (Computer-Aided Gear Selection), and is present on many sporting cars produced in the US from the 1990s onwards on every car fitted with the Tremec T-56 and TR-6060, including the [Dodge Viper](/source/Dodge_Viper),<ref name="washt08"/> [Pontiac Firebird](/source/Pontiac_Firebird),<ref name="jkenz96"/> 2004-2006 Pontiac GTO, [Pontiac G8 GXP](/source/Pontiac_G8), V8/SS [Chevrolet Camaro](/source/Chevrolet_Camaro) and [Cadillac CTS-V](/source/Cadillac_CTS-V).<ref name="wojdy05"/>

==Criticism==
The effect of the system on normal driving has been described as "dreaded",<ref name="jkenz96"/> "awful"<ref name="jkenz05"/> and "annoying".<ref name="washt08"/> In 1994 Popular Science noted that "if something like an oncoming truck makes you change your mind, the car's response is doggedly slow."<ref name="jmcrw94"/>

==Eliminators==
Owners manuals for the Corvettes in which it was first implemented contained photographs of the system components "captioned to caution drivers not to disconnect [the] wire, or the skip-shift function would no longer function."<ref name="allen"/> These photos, along with the continuing, decades-long ability to bypass the system easily with a simple resistor, make it clear that [GM](/source/General_Motors) has never intended to make the system difficult to bypass. If anything, it has been made as simple as possible while still satisfying federal regulations. Skip shift eliminators are produced for quick and simple DIY installation to circumvent the GM CAGS system.<ref name="newtn06"/> {{as of|2005|bare=y|pre=In}}, these were commercially available for about {{US$|20|2009|round=0}}–{{US$|40|long=no}}, or could be made with a little soldering for about {{US$|7|long=no}}.<ref name="wojdy05"/> Notably, neither workaround will eliminate the "1-4 skip shift" dash indicator light, which will continue to operate regardless. [ECU](/source/Engine_Control_Unit) tuning is required to eliminate the dash indicator light.

==References==
<references>

<ref name="jkenz05">{{cite web|url=http://www.wheels.ca/article/28050|archive-url=https://web.archive.org/web/20111003090655/http://www.wheels.ca/article/28050|url-status=dead|archive-date=October 3, 2011|title=2006 Chevrolet Corvette|author=Jim Kenzie|work=Wheels.ca|date=16 July 2005}}</ref>
<ref name="jkenz96">{{cite magazine|title=Firebird burns street Pontiac brings back Ram Air heritage and asphalt-ripping power|author=Jim Kenzie|work=Toronto Star|date=27 April 1996|page=H1}}</ref>
<ref name="jmcrw94">{{cite book|url=https://books.google.com/books?id=UJtPrlfCMwUC&pg=PA71|publisher=Popular Science|edition=March 1994|title=Muscle Cars|page=71|author=Jim McCraw|date=March 1994|access-date=2024-08-30|via=[Google Books](/source/Google_Books)}}</ref>
<ref name="newtn06">{{cite book|url=https://books.google.com/books?id=1TPCgPosnjAC&pg=PA85|page=85|title=Corvette C5 Performance Projects: 1997-2004|year=2006|author=Richard Newton|isbn=0-7603-2081-0|publisher=Motorbooks|access-date=2024-08-30|via=[Google Books](/source/Google_Books)}}</ref>
<ref name="wojdy05">{{cite web|url=https://jalopnik.com/how-to-disable-gms-manual-skip-shift-for-seven-bucks-5252686|work=Jalopnik|title=How To Disable GM's Manual Skip Shift For Seven Bucks|author=Ben Wojdyla|date=13 May 2009|access-date=2024-08-30}}</ref>
<ref name="washt08">{{cite news|url=https://www.washingtontimes.com/news/2008/jul/04/dodge-viper-srt10-gets-you-there-in-a-hurry/|title=Dodge Viper SRT10 gets you there in a hurry|work=Washington Times|date=4 July 2008|author=Arv Voss|access-date=2024-08-30}}</ref>
<ref name="allen">{{cite web|url=https://www.popularmechanics.com/cars/g543/6-ways-detroit-gamed-the-cafe-standards/|title=6 Clever Ways the Car Industry Has Gamed the CAFE Fuel Economy Standards|publisher=Popular Mechanics|author=Mike Allen|date=30 June 2011|access-date=2024-08-30}}</ref>

</references>

Category:Automotive transmission technologies

{{auto-tech-stub}}

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Adapted from the Wikipedia article [Shift blocking](https://en.wikipedia.org/wiki/Shift_blocking) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Shift_blocking?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.