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 Randall C Your Own Question

Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11268
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
13677702
Type Your Chevy Question Here...
Randall C is online now
A new question is answered every 9 seconds

My Chevy Tahoe 07 interval wipers are not working. High and

Resolved Question:

My Chevy Tahoe '07 interval wipers are not working. High and low speed is normal.
Submitted: 4 years ago.
Category: Chevy
Expert:  Randall C replied 4 years ago.
Hello, does the " mist" function work?
Customer: replied 4 years ago.
Yes !
Expert:  Randall C replied 4 years ago.
The wiper system in your vehicle uses different delay modes built into the multifunction/turn signal switch.Each delay mode has a different resistor. ( i put diagram below if you are familiar with one and if you look at top, you will see multifunction switch and the built in resistors to control different delay)
The problem is the BCM or body computer takes each of the different resistor readings and controls the delay of the motor. The fact you have high and low but no delay at all leads me to think you may have a bad BCM. The circuit in the BCm that reads the different resistor readings has failed. It is NOT a motor problem nor ground nor fuse. it has to do with the signal from switch to BCM.
Unfortunatley this is not user friendly to diagnose. However, a shop with a scanner can vew all the different resisitr values and tell you 100% real quick if the switch is bad or BCM.I am thinking BCM since you have NO delay speeds. If you lost say one of them, i would lean to swtich. The swicth can not be ruled out but only a scanner hooked up can confirm this since your wipers are controlled by a computer unlike older vehicles. here is the "technical description" and the diagram





WINDSHIELD WIPERS
The windshield wiper/washer switch signal circuits are inputs to the body control module (BCM) and the BCM controls wiper motor low speed operation, washer pump and high speed operation. The windshield wiper/washer switch is provided a low reference from the BCM and each of the switch signal circuits is supplied 12 volts through a resistor and monitored within the BCM. During LOW or INTERMITTENT operation the wiper switch low signal circuit is closed to the low reference circuit through a series of resistors within the switch assembly and the signal circuit voltage monitored by the BCM will depend on the switch contact location to the resistor assembly. During HIGH or WASH operation the high and wash switch signal circuits are closed directly to the low reference circuit within the switch assembly and nearly all the signal circuit voltage will be dropped across the BCM resistors. The BCM controls the wiper motor through the Wiper Relay and the Wiper High Relay. During any wiper motor function that uses low speed the BCM supplies the voltage to energize the Wiper Relay and battery voltage will be supplied from the Wiper Relay through the de-energized Wiper High Relay to the wiper motor low speed control circuit. During high speed wiper motor operation the Wiper Relay is energized as in low speed and the BCM provides a ground to energize the Wiper High Relay and the battery voltage is supplied to the wiper motor high speed control circuit. Wiper motor park operation is controlled by the BCM using an input from the park switch within the wiper motor assembly. The BCM supplies the park switch signal circuit 12 volts through a resistor then monitors the circuit. Whenever the wiper motor is out of the park position the park switch signal circuit is closed to ground and nearly all the signal circuit voltage will be dropped across the BCM resistor. When the wiper switch is turned to the OFF position while the wiper motor is somewhere in mid-cycle, the BCM will continue to operate the motor until the wipers reach the park position. If the ignition is turned OFF while the wipers are in mid-cycle, the wipers will stop immediately where they are and the BCM will park the wipers the next time the ignition is cycled ON.

graphic
Customer: replied 4 years ago.
Ok, I found a black box under the dashboard with P/N 15901388. Is this the BCM ?
Expert:  Randall C replied 4 years ago.
Each application/vehicle will have different BCM # XXXXX on options etc.. I suspect you are looking at BCM. Info is below. Just wanted to remind you I am leaningto BCM but only a scanner can confirm 100%. A new BCM can easily be $500 +/- so I would hat for you to swap out and have same problem. there is no way i can give a 100% answer without viewing scanner data but still I lean to BCM as the problem Hope this helps

BODY CONTROL MODULE REPLACEMENT



 

Customer: replied 4 years ago.

ok, Launch X431-Scanner is connected... Can see all data from Body Control Modul - Washer/Whiper.... what kind of datas you need ?

 

Expert:  Randall C replied 4 years ago.
Full diagnostic instructions for scanner are below to test switch/BCM /Motor

BCM And Wiper Switch Verification
  1. Ignition ON, observe the scan tool BCM Windshield Wiper Switch parameter. The reading should display Off, Intermittent, Low and High while rotating the wiper switch.
    • If one or more of the wiper delay parameters are inoperative and the wiper low speed parameter functions, replace the turn signal/multifunction switch.
    • If the low speed and/or high speed parameters are inoperative, perform the Multifunction Switch Circuit/System Testing and/or the Multifunction Switch Component Test.
  1. Observe the scan tool BCM Wiper Park Switch parameter. The reading should display Active when the wipers are parked and Inactive with the wipers ON or out of the park position.
    • If the Wiper Park Switch parameter is always Active or Inactive, perform the Wipers do not Park Circuit/System Testing.
  1. If all wiper position parameters displayed correctly on the scan tool, perform the Wiper Motor Circuit/System Testing and/or the Wiper Motor Component Test BCM And Wiper Motor Verification
  1. Command the windshield wiper motor to the off, low speed and high speed modes with a scan tool. The wipers should perform the commanded state.
    • If one or more of the commanded states do not work, perform the Wiper Motor tests in Circuit/System Testing and/or Component test.
  1. If all the wiper motor speeds function, perform the Multifunction Switch Circuit/System Testing and/or the Multifunction Switch Component Test.

CIRCUIT/SYSTEM TESTING

Multifunction Switch Circuit/system Testing

  1. Ignition OFF, disconnect the C3 harness connector at the turn signal/multifunction switch.
  2. Ignition OFF, test for less than 15 ohms of resistance between the ground circuit terminal M and ground.
    • If greater than 15 ohms , test the ground circuit for an open/high resistance. If the circuit tests normal, replace the body control module.
  1. Verify the scan tool Windshield Wiper Switch parameter is Off.
    • If not Off, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the body control module.
  1. Verify the scan tool Wiper High Speed Switch parameter is Inactive.
    • If not Inactive, test the signal circuit terminal K for a short to ground. If the circuit tests normal, replace the body control module.
  1. Install a 3-amp fused jumper wire between the signal circuit terminal N and ground. Verify the scan tool Windshield Wiper Switch parameter is Switch Fault.
    • If not Switch Fault, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the body control module.
  1. Install a 3-amp fused jumper wire between the signal circuit terminal K and ground. Verify the scan tool Wiper High Speed Switch parameter is Active.
    • If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the body control module.
  1. If all circuits test normal, replace the turn signal/multifunction switch. Wipers Do Not Park Circuit/system Testing
  1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
  2. Ignition ON, verify the scan tool BCM Wiper Park Switch parameter is Inactive.
    • If not Inactive, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the body control module.
  1. Install a 3-amp fused jumper wire between the wiper motor park switch signal circuit terminal 3 and ground. Verify the scan tool Wiper Park Switch parameter is Active.
    • If not Active, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the body control module.
  1. If all circuits test normal, replace the windshield wiper motor.

Wiper Motor Circuit/system Testing

  1. Ignition OFF, disconnect the underhood fuse block.
  2. IMPORTANT: The underhood fuse block bottom view illustration is an inverted view of the connectors in the bracket assembly. Test for less that 5 ohms of resistance between the wiper relay ground circuit in connector C2 terminal N5 and ground.
    • If greater than 5 ohms , test the ground circuit for an open/high resistance.
  1. Connect a 60A fused jumper from the battery supply terminal in connector C6 to the LBEC 2 fuse output circuit 42 in connector C5 terminal F2.
  2. Connect a test lamp from the WIPER 1 relay control circuit in connector C5 terminal K3 to ground.
  3. Ignition on, command the Wiper Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the body control module.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the body control module.
  1. Connect a test lamp from battery voltage to the WIPER 2 relay control circuit in connector C5 terminal K1.
  2. Command the Wiper High Speed Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the body control module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the body control module.
  1. Ignition OFF, connect the underhood fuse block.
  2. Disconnect the harness connector at the wiper motor.
  3. Test for less that 1 ohm of resistance between the wiper motor ground circuit terminal 2 and ground.
    • If greater than 1 ohm , test the ground circuit for an open/high resistance.
  1. Connect a test lamp between the low speed motor control circuit terminal 1 and ground.
  2. Ignition on, command the Wiper Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
  1. Connect a test lamp between the high speed motor control circuit terminal A and ground.
  2. Command the Wiper High Speed Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
  1. If all circuits test normal, replace the windshield wiper motor.

COMPONENT TESTING

Multifunction Switch

Wiper Switch Values

  1. Ignition OFF, disconnect the C3 harness connector at the turn signal/multifunction switch.
  2. Test the resistance between terminals M and N. Rotate the wiper switch and compare the resistance readings to the values in the Windshield Wiper Switch Values table below for MIST, each DELAY and LOW speed.
    • If the resistance is not within the specified range, replace the turn signal/multifunction switch.
  1. Test for infinite resistance between terminals M and K while rotating the wiper switch to MIST, each DELAY and LOW speed positions.
    • If the less than infinite, replace the turn signal/multifunction switch.
  1. Test for less than 5 ohms of resistance with the wiper switch in the High speed position. to.
    • If greater than 5 ohm , replace the turn signal/multifunction switch.
  1. Test for infinite resistance between terminals M and L while rotating the wiper switch to MIST, each DELAY and LOW speed positions.
    • If less than infinite, replace the turn signal/multifunction switch.
  1. Test for less than 5 ohm of resistance while pressing the WASHER switch.
    • If greater than 5 ohm , replace the turn signal/multifunction switch.

IMPORTANT: If the switch tests open in any switch position other than Off, test the wiper/washer switch signal circuits for a short to voltage before replacing the switch.

Windshield Wiper Motor Dynamic Test

  1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
  2. Install a 25-amp fused jumper wire between the control terminal 1 and 12 volts . Install a jumper wire between the ground terminal 5 and ground.
  3. The wiper motor should be in low speed mode.
    • If the wiper motor is not in the low speed mode replace the motor.
  1. Install a 25-amp fused jumper wire between the control terminal 4 and 12 volts . Install a jumper wire between the ground terminal 5 and ground.
  2. The wiper motor should be in the high speed mode.
    • If the wiper motor is not in the high speed mode replace the motor.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

 



 

Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11268
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
Randall C and 9 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