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 Paul M ASE Master Your Own Question
Paul M ASE Master
Paul M ASE Master, ASE Master Tech
Category: Chevy
Satisfied Customers: 4683
Experience:  ASE Master Tech 20+ Years
Type Your Chevy Question Here...
Paul M ASE Master is online now
A new question is answered every 9 seconds

Chevrolet Suburban 1500 LT: I have a 2002 Chevy Suburban.

This answer was rated:

I have a 2002 Chevy Suburban. My dash lights go out when the headlights come on. I have checked the voltage at the ILLUM fuse and it does vary when I turn the dimmer up and down. What else should I try?

Hello I'm Paul and I will help you with an Answer to your Question


there is a common failure with the headlight switch that causes this problem


I am attaching the testing information


click here to view test


suspect a bad headlight switch


Remember to rate my answer positive so I get credit for my help.


If you need more help just log in to the site and reply the question will remain for follow up.


Customer: replied 3 years ago.

Hi Paul.


I retested the voltage at ILLUM and now don't see the voltage vary when I turn the dimmer up and down. I'm pretty sure it did that before.


Jumping the Orange and Light Blue wires behind the switch had no effect. I assume it was the larger Orange that was indicated (there is also a smaller one). The clock light went out as it does when I turn the headlights on.



does the orange have 12 volts on it?


When you jump the Orange 12 volts to the Light Blue does the dash Light up?


does the ILLUM fuse have 12 volts to both sides with the Orange jumped to the Light Blue?

Please answer the above questions and I can tell you the next step in testing



Customer: replied 3 years ago.

Both Orange wires have 12V. The larger one is in the "B" position. The smaller one is not labeled, but would be "D". The Light Blue is "A".


Jumping Orange "B" to Light Blue "A" causes the clock light to go out. I do not see any dash lights. It is daylight, so I'm going by the clock light.


With the jumper in place, there is no voltage on either side of the ILLUM fuse. One side causes my digital meter to fluctuate, but mostly in the mV range.


the light blue feeds the ILLUM fuse


if you jumper power 12 v to the Light Blue from the Orange and the ILLUM fuse has no power the Light Blue wire is broken between the headlamp switch and the ILLUM Fuse


are you sure your getting a good reading on the fuse?


if no power on the fuse ILLUM but power at Light Blue then the wire is broken somewhere between headlamp switch and the fuse... (often problems occur inside the fuse panel under the fuse...

take a 12 volt jumper wire and touch the fuse the dash lights should come on... if so you need to find the open circuit in the Light Blue wire between the headlamp switch and the ILLUM fuse


I am attaching a wiring diagram so you can see how it runs

click here to view

let me know what you find and if you need more help



sorry for any confusion but looking at the diagram


the Light Blue first feeds the INT Park Fuse #24


does this fuse have power? with the light blue jumped?


disregard the last message test the INT Park Fuse rather than the ILLUM fuse



I just studied the diagram in depth


jump the Orange to the Dark Green B to K


does the ILLUM fuse get power and dash light uP?

if so but it does not with the headlamps on and dimmer turned up the headlamp switch is bad


sorry for the confusion I had to dig into multiple diagrams to get this figured out



Customer: replied 3 years ago.

Okay, I will go test this. It's a bit of a walk, so sorry for the delays between messages.


BTW, jumping the Orange "B" to the ILLUM did light up the dash, so we're making progress.

ok let me know what you find

Customer: replied 3 years ago.

Jumping Orange "B" to Dk Green "K" did cause the dash lights to come on. Are you sure this indicates the switch is at fault? Why did the first document you linked instruct to jump the Lt Blue?

the original diagnosis was from a technicians database


the Light Blue is for illumination when park light relay is on


the Dark Green actually feeds the Illumination fuse


it gets 12 volt feed from the Orange wire through the Switch when (Park or Headlights are on) to the Dark Green


if Orange has Power


and Headlight switch is on and Dark Greek does not get power coming out of the switch with dimmer set to on position then the Headlamp switch is bad.

Power from the Orange 12 volts... runds Through the headlight switch/dimmer to the Dark Green ..


so if you plug in the headlamp switch and turn headlight on there is no dash lights


but if you jump the Orange to Dark Green they come on Headlamp switch is bad for sure


sorry for the confusion but not sure who wrote the original diagnostic I attached


but the headlamp switch is bad



Paul M ASE Master, ASE Master Tech
Category: Chevy
Satisfied Customers: 4683
Experience: ASE Master Tech 20+ Years
Paul M ASE Master and 4 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... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...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
< Previous | 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:

  • GM Tech (Cam)

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
< Last | Next >
  • GM Tech (Cam)'s Avatar

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
  • Tim's Auto Repair's Avatar

    Tim's Auto Repair


    Satisfied Customers:

    Have owned a repair shop for 25 yrs.
  • Gary's Avatar


    Chevy Technician

    Satisfied Customers:

    15 years GM master tech
  • Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    ASE Master Certification. GM World Class Certification
  • John's Avatar


    Master A.S.E Automotive technician

    Satisfied Customers:

    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • Don 'Mo Lurch''s Avatar

    Don 'Mo Lurch'

    Auto Mech / Electronics

    Satisfied Customers:

    Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
  • Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    18+yrs experience. State Inspector and Chevy Diagnostics