Fan only works on high 02 gmc hd 2500

Making a new post as a folloup doesn't work on Fixya, because this post has no context to the other post you made on 8th October. Jim is unlikely to see it in the same way I didn't see your original post. Click on this link below and click COMMENT under Jim's post and ask him. He will get a notification that you would like further help.

https://www.fixya.com/cars/t29842825-elec_prob_will_not_start_unless_hold

The 'inhibitor switch' is the part that makes it that you can only start the vehicle in Park.
..

O2 sensors are located before and after catalytic convertors. Unplug sensors and remove with deep socket.

Light switch faulty looks like,

In relation to these problem there are few solved help links,i suggest you to go through the list and click the required link:-----

Power Steering going out? http://schematicsdiagram.blogspot.in/2012/04/power-steering-going-out.html

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How to Replace power steering pump on Chevy silverado 2500 HD? http://technoanswers.blogspot.in/2012/02/how-to-replace-power-steering-pump-on.html
--------------- How to replace Power steering rack and pinion gear on Chevy Silverado 2500 HD? http://technoanswers.blogspot.in/2012/02/how-to-replace-power-steering-rack-and.html
------------- Power Recirculating Ball Steering Gear removal on Chevy silverado 2500 HD? http://technoanswers.blogspot.in/2012/02/power-recirculating-ball-steering-gear.html
----------- Chevy Silverado 2500 HD steering wheel replacing Procedure? http://technoanswers.blogspot.in/2012/02/chevy-silverado-2500-hd-steering-wheel.html
----------- Steering Wheel Locked? http://schematicsdiagram.blogspot.com/2011/12/steering-wheel-locked.html

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How to Remove Power steering Pressure Hose on Dodge Stratus http://schematicsdiagram.blogspot.com/2011/12/how-to-remove-power-steering-pressure.html

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How to replace power steering pump on Mitsubishi Diamante?

http://howtobyme.blogspot.com/2012/01/how-to-replace-power-steering-pump-on.html

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How to bleed power steering pump on Toyota? http://repairhelpcenter.blogspot.in/2012/02/how-to-bleed-power-steering-pump-on.html

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----------How to replace power steering pump on Toyota Land cruiser?

http://repairhelpcenter.blogspot.in/2012/02/how-to-replace-power-steering-pump-on.html

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Steering service light ON GMC Sierra Denali?

http://technoanswers.blogspot.in/2012/02/steering-service-light-on-gmc-sierra.html

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Steering service light came on 2004 Pontiac Grand Prix

http://technoanswers.blogspot.in/2012/02/on-one-my-pontiac-grand-prix-relatred.html

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Check power steering message on Toyota?

http://schematicsdiagram.blogspot.in/2012/02/check-power-steering-message-on-toyota.html

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How to remove power steering pulley on 2002 Ford Taurus? http://repairhelpcenter.blogspot.in/2012/03/how-to-remove-power-steering-pulley-on.html
---------1992 Ford Aerostar Power steering and Alternator belt routing diagram? http://carbeltrouting.blogspot.com/2011/12/1992-ford-aerostar-power-steering-and.html

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How to replace Power Steering Pump on Acura Car Models?

Also bleeding:

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-power-steering-pump-on.html

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How to replace Steering Linkage on Acura Car Models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-steering-linkage-on.html

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How to replace power steering pressure hose on mustang? http://technoanswers.blogspot.in/2012/02/how-to-replace-power-steering-pressure.html

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STEERING SQUEAKS http://alltypesofpartsreplacing.blogspot.com/2012/10/steering-squeaks.html
----------- Steering Column Diagram For 1990 Jeep Wrangler http://schematicsdiagram.blogspot.in/2012/07/steering-column-diagram-for-1990-jeep.html
------------- How to replace Steering Wheel on Acura Car Models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-steering-wheel-on-acura.html

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How to replace Power Steering Pump on 1999 Acura TL?

http://howtobyme.blogspot.com/2011/11/how-to-replace-power-steering-pump-on.html

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These details will help.

Thanks.

Replace the headlight dimmer switch on the steering column and check the connector to it fro signs of overheating, replace connector and switch as one repair. Do not use crimp connectors, solder all wires as needed and use shrink tube to insult the solder joints.

It is most likely the multifunction switch ( turn signal switch ) that is faulty ....

Is fuse ok,Then is there power to resistor.If no power to resistor I would check the blower control switch on dash

The resistors or the relay . The resistors for all the other speeds are defective. High speed doesn't go threw a resistor that is straight B+.

try checking your neutral safety switch.

THERE HAVE BEEN ALOT OF PLOBLEMS WITH THE SHIFTER HANDLE/SWITCH. THE BEST WAY TO VERIFY CONCERN IS USE A DIAG. SCANNER & VIEW TRANSMISSION DATA DISPLAY WHILE ENGINE RUNNING. THE SWITCH IN THE SHIFTER IS FAULTY. IF YOU SEE NO INPUT CHANGE WHILE DEPRESSING SWITCH THIS IS YOUR CONCERN.