How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask goodwrench9124 Your Own Question

goodwrench9124
goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3429
Experience:  Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
5720312
Type Your Chevy Question Here...
goodwrench9124 is online now
A new question is answered every 9 seconds

I have a 2000 Suburban, my tow/haul does not work, and the ...

Resolved Question:

I have a 2000 Suburban, my tow/haul does not work, and the engine sometimes revs up, are these related problems, if so what should I look for?
Submitted: 7 years ago.
Category: Chevy
Expert:  goodwrench9124 replied 7 years ago.
hello, are you saying the tow/haul mode switch on shifter doesnt work, and when does it just seem to revs up????
Customer: replied 7 years ago.
sometimes after it is warmed up,it revs up to 1200 rpms, yes, the switch on the shifter doesnt work
Expert:  goodwrench9124 replied 7 years ago.
ok normally the switch that is in the shifter on column, there are two wires that run out of the shifter inside the column usually will break they are very small wires. the column covers will have to be removed for inspection. your other concern about reving up, i thinking maybe trans is slipping under load???
Customer: replied 7 years ago.
when i am sitting in park it revs up
Expert:  goodwrench9124 replied 7 years ago.
ok it has a idle concern, normally when the idle goes high it is caused by a vac leak. have you had a check engine light coming on???
Customer: replied 7 years ago.
no check engine light
Expert:  goodwrench9124 replied 7 years ago.

i have included the tow haul switch wiring for you to look at, i going to do a little research for your idle so can you give me a few mins to review

Tow/Haul Switch/Indicator Always On or Inoperative (4.8L and 5.3L)


Object Number: 607409  Size: LF

Expert:  goodwrench9124 replied 7 years ago.

there is a tsb for a unstable idle and also states for oil consumption. what this tsb is stating that excessive carbon build up in throttle body which allows air to enter engine. also there is another area to look at on these trucks are the intakes, like to leak vac causing various running problems. you can take some carb cleaner and spray where the intake meets the heads and if the idles changes, you know the intake is leaking vac.

Document ID#(NNN) NNN-NNNN
2000 Chevrolet Chevy Suburban - 4WD

 

Subject:Increased Accelerator Pedal Effort, Idle Instability (Clean Throttle Body and Adjust Blade) #02-06-04-054B - (03/17/2003)

 

Models:1999-2002 Chevrolet Silverado
2000-2002 Chevrolet Suburban, Tahoe
2002 Chevrolet Avalanche
1999-2002 GMC Sierra
2000-2002 GMC Yukon, Yukon XL
with 4.8L or 5.3L V8 Engine (VINs V, T, Z -- RPOs LR4, LM7, L59)

 


This bulletin is being revised to add condition information. Please discard Corporate Bulletin Number 02-06-04-054A (Section 06-Engine).


Condition

Some customers may comment on an idle instability and/or a higher than expected accelerator pedal effort from the idle position.

Cause

Condition may be caused by deposits in the throttle body bore and on the throttle plate.

Correction

Important: This procedure only applies to cable actuated throttle bodies on the models listed above. This procedure should not be performed on electronically controlled throttle bodies or on any vehicle or engine that is not listed above in the Models section.

  1. Verify that the cause for this condition is not a damaged or binding throttle cable.
  2. Remove the air intake duct. Refer to Air Cleaner Duct Replacement.
  3. Inspect the vehicle for installation of a fixed orifice PCV valve, refer to Corporate Bulletin Number 01-06-01-029B for PCV valve identification. Vehicles undergoing this throttle body procedure MUST use a Fixed Orifice PCV Valve, P/N 12572717.
  4. Clean throttle body bore and throttle valve plate of carbon using a shop rag and an appropriate cleaner. Refer to Engine Controls Repair Procedures - Throttle Body Cleaning Procedure.
  5. Select the correct plug for the size of the air bypass hole in the throttle body being serviced. Use a 1/8-inch (.125") drill bit to determine which plug to use.
    Vehicles built before introduction of the Fixed Orifice PCV Valve will have a 3.75 mm (.150") air bypass hole in the throttle plate. The 1/8-inch drill bit is smaller than the air bypass hole in these throttle bodies and can be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the yellow plug, P/N 12580749.
    Vehicles built after introduction of the Fixed Orifice PCV Valve will have a 2.6 mm (.104") air bypass hole in the throttle plate. The 1/8-inch drill bit is larger than the air bypass hole in these throttle bodies and cannot be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the red plug, P/N 12581011.

    Object Number: 927140  Size: MF

  6. Insert the appropriate plug (1) into the air bypass hole in the throttle plate. Insert the "tail" end of the plug through the throttle plate air bypass hole.
    Object Number: 927142  Size: MF

  7. Open the throttle plate to allow access to the tail end of the plug. Pull the tail section to securely position the plug into the air bypass hole and trim excess material (1) from plug.
  8. Turn ignition key to the on position, with engine off.
  9. Use the Tech 2 Scan tool to read initial TPS voltage.

    Important: TPS voltage cannot exceed .69 V. If the vehicle has an initial TPS voltage greater than .61 V, replace the Throttle Body Assembly. This part is currently on parts restriction. Contact the General Motors Powertrain Quality Center at(NNN) NNN-NNNNfor assistance.

  10. Using the Tech 2 Scan tool and a T15 driver to rotate the Minimum Air Rate screw, increase TPS voltage by .08 Volts (Refer to TPS Voltage Chart below).
  11. Turn ignition key to the off position. Verify that the accelerator pedal moves freely - Depress the accelerator pedal to the floor and release.
  12. Install the air intake duct. Refer to Air Cleaner Duct Replacement.
  13. Start engine.
  14. Using the Tech 2 scan tool, monitor TPS voltage and verify the TPS voltage is no greater than 0.69V.
  15. Road Test Vehicle.

Important: If an increased accelerator pedal effort condition still exists after performing this bulletin, throttle body replacement may be required. Please contact the General Motors Powertrain Quality Center at(NNN) NNN-NNNNfor assistance, as the throttle body is currently on a parts restriction program.


TPS Voltage Chart

Initial TPS Voltage

TPS Voltage After .08 Volt Increase

0.45 V

0.53 V

0.47 V

0.55 V

0.49 V

0.57 V

0.51V

0.59 V

0.53 V

0.61 V

0.55 V

0.63 V

0.57 V

0.65 V

0.59 V

0.67 V

0.61 V

0.69 V

If initial TPS voltage is greater than .61 V Replace Throttle Body Assembly

Parts Information

Part Number

Description

Qty

12580749

Plug, Throttle Plate - Yellow

1

12581011

Plug, Throttle Plate - Red

1

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

J5984

Throttle Body - Clean and Adjust

0.6 hr

Condition/Concern:

 

99 through 05 GEN III truck engines may experience any of the following:

  1. A cold rough idle that diminishes as the engine warms up.
  2. Possible DTCS P0171, P0174, or P0300.
  3. Random misfires at idle.

Recommendation/Instructions:

 

The intake gasket seals may be leaking around the intake ports, causing a lean condition. The intake gasket seals may leak around the bottom side of the port, making it a challenge to detect the vacuum leak. The technician may also notice lower than normal MAF readings if the intake seals are leaking.

  1. If leaking intake gasket seals are found, replace the intake gaskets. During the repair be sure to use the current GMSPO part number for replacement intake gaskets. The current GMSPO part number for intake gaskets will have a teal green intake gasket seal. The old version of the intake gaskets were orange in color. Use only the teal green colored gaskets for a repair.
  2. The intake plenum should also be checked for excessive warpage that may cause an uneven clamping pressure of the seal. If the plenum is found to be warped it will need to be replaced. Service Information states, "An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area should be replaced". Intake warpage is measured at the gasket sealing surfaces, and should be measured within a 200 mm (7.87 in) area. This measurement is across only two of the intake runner port openings. Measurements taken across the entire distance of all four intake runner ports will lead to unnecessary manifold replacements.

I hope this info was helpfull and anything you dont understand please ask me to explain

goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3429
Experience: Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
goodwrench9124 and 15 other Chevy Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6870
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    5404
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1912
    18+yrs experience. State Inspector and Chevy Diagnostics