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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1513
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Chevrolet Silverado, Power at the fuse but brake lights

Customer Question

Chevrolet Silverado,
Power at the fuse but brake lights don't work.
Submitted: 6 months ago.
Category: Chevy
Expert:  Don 'Mo Lurch' replied 6 months ago.

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sorry for the delay............
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Please post Model of Silverado & if Automatic or 4x4
Greetings...... “Hi, I’m Don (aka MOLurch) and I look forward to helping you!”
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IF you have Voltage + on "both sides" of the Fuse, then test the ORANGE wire at the Brake Switch under the dash with Key ON
IF there is Voltage +
Test the WHITE wire at the Brake Switch with Pedal pushed down
Let me know what you find

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Customer: replied 6 months ago.
I'll try this tommorrow
Expert:  Don 'Mo Lurch' replied 6 months ago.

please let me know

thank you

Customer: replied 6 months ago.
There is no power but I did find a plug dangling which has an orange and white wire. Orange has power. Where does it plug in? I'll send you a photo
Expert:  Don 'Mo Lurch' replied 6 months ago.

Please post Model of Silverado & if Automatic or 4x4

Expert:  Don 'Mo Lurch' replied 6 months ago.

The plug you show in picture is:
Brake/Clutch Harness To Beacon Harness (With RPO Code 5G4/TRW)
.

The wires I need checked is plugged into the Brake Pedal Switch which is mounted to the Brake Pedal Arm
It is a "6" PIN Connector

Customer: replied 6 months ago.
It s 2500hd Silverado, automatic 4x4
Customer: replied 6 months ago.
Orange no power
Expert:  Don 'Mo Lurch' replied 6 months ago.

thanks for the added info

which ORANGE wire are you referring to?
the one in your picture or at the Brake Switch?
Which Fuse did you check?
Is there Voltage + on "both sides" of Fuse?

Customer: replied 6 months ago.
I checked fuse and there is power at fuse. No power on Orange at brake pedal
Expert:  Don 'Mo Lurch' replied 6 months ago.

you posted that there is "power at fuse".........?
Is there Voltage on "both sides of Fuse" & is it Fuse "STOP LP" in the under Hood Fuse Box?
IF so, & there is Voltage + on "both sides of Fuse, then you have a break from the Fuse Box to the Brake Pedal Switch

Using a long piece of wire:

Connect one end of a piece of wire to Fuse "STOP LP"
Connect the other end of the piece of wire to the ORANGE wire at the Brake Switch Plug
does brake lights work?

Customer: replied 6 months ago.
Power on both sides of fuse StopLp
Under hood no power at brake. Daughter is graduating College. So I won't do the wire test until Monday
Expert:  Don 'Mo Lurch' replied 6 months ago.

thanks......I know about graduating this week....2 more girls to go.........
Let me know what you find

thanks

Expert:  Don 'Mo Lurch' replied 6 months ago.

Did you need more info?
Please respond or Rate my answer

thank you

Customer: replied 6 months ago.
Hey Don,
I tried jumping the wire from fuse to orange and I also tried the white. There was power at the end of the jumper but no brake lights also tried pressing pedal but no response.
Expert:  Don 'Mo Lurch' replied 6 months ago.

was this at the "6" PIN Connector on the Brake Pedal?
Does the 3rd Brake Light work?

Customer: replied 6 months ago.
I did connect it to the #6 orange on brake pedal.
Expert:  Don 'Mo Lurch' replied 6 months ago.

sorry I will opt out, as I do not believe we are communicating
please do not respond to this, as it will lock question
IF someone else has more info, they will post here

Expert:  Juan Crespo replied 6 months ago.

Hi there. Different expert here.

System voltage at the STOP LP fuse, but not at the Orange wire on the stop lamp switch connector, indicates an open circuit. To test, temporarily run a fused jumper in place of the Orange wire from the fuse to the stop lamp connector. If stop lamps work, trace and repair open circuit between stop lamp switch connector and underhood fuse box - as an option, and since this is a dedicated circuit for the stop lamps, you could also run a new wire from the fuse box to the stop lamp switch to replace the existing circuit running through the Orange wire.

Please let me know if you have any other questions.

Customer: replied 6 months ago.
I'll check it in am
Expert:  Juan Crespo replied 6 months ago.

I'm usually online weekdays from 2 to 8PM EST. Look forward to hearing from you then.

Customer: replied 6 months ago.
Juan,
Sorry for delay but I am working on my brake issue again. The fuse is live but when I do a continuity test the orange wire at the fuse is not the wire connected to the brake pedal. The orange wire is the wire hanging unplugged under the dash. I showed this to the other tech and he said it was brake clutch harness to beacon harness. But that orange wire is the one directly connected to the brake fuse . I jumped that wire to the orange wire and also tried the white wire on brake pedal with no luck.
Expert:  Juan Crespo replied 6 months ago.

I don't have a problem with the delay, but I do with you doing things I didn't recommend doing. Please follow the instructions as I previously posted:

"To test, temporarily run a fused jumper in place of the Orange wire from the fuse to the stop lamp connector. If stop lamps work, trace and repair open circuit between stop lamp switch connector and underhood fuse box - as an option, and since this is a dedicated circuit for the stop lamps, you could also run a new wire from the fuse box to the stop lamp switch to replace the existing circuit running through the Orange wire."

I'd understand if you want to do things your own way instead of following my advice, but, if that's how you want to procedd, then I wouldn't be able to help you. Please let me know if you have any questions.

Customer: replied 6 months ago.
The problem is that another tech has also instructed me to try things. Is the stop lamp connector the orange wire on the brake pedal?
Expert:  Juan Crespo replied 6 months ago.

OK. The no-stop lamp issue is mostly caused by bad connections. The next place that you should check is at the junction block for the rear lamps located on the left frame rail near the rear of the vehicle.

Look at the attached diagram and you will see the connector legend next to the highlighted junction block. With brakes applied, you'll be checking power coming in and out of the junction block (Lt Blue wire in and out)

Please let me know what you find.

Customer: replied 6 months ago.
There is two light blue wires at the junction box. No power to either with key on and brake pedal depressed.
Expert:  Juan Crespo replied 6 months ago.

According to the diagram there should be three Lt Blue wires; one bringing power to Blue connector C1 terminal 8; another Lt Blue wire carrying power from Gray connector C2 terminal 7 to the Left Stop Lamp; and yet another Lt Blue wire carrying power from Black connector C4 terminal 7 to the Right Stop Lamp.

If the junction block is bad, there'll be power only coming in to the Blue connector.

Customer: replied 6 months ago.
I didn't get power on the two that I tried. The backup, running lights work ok. Think turn signals also but not positive. I'll check three lt blue wires coming in to box in am
Expert:  Juan Crespo replied 6 months ago.

OK. Please remember that I'm online weekdays from 2 to 8PM EST.

Customer: replied 6 months ago.
Jaun,
Just to give you alittle perspective, this truck was a roll over. I replaced the cab but used the original wire harness etc.
So let's recap ,
There is power at the 25 brake fuse under hood.
There is no power to the orange wire on brake pedal.
If I use a fused jumper and press pedal there is no brake lights.
With pedal depressed there is no power to the two Lt blue wires at the rear plug also there is only two Lt blue wires coming into that junction terminal. Photo attached
Expert:  Juan Crespo replied 6 months ago.

OK. The wire may have a different color, but I doubt it (look at the attached diagram). Check for power at the wire going to the Blue connector terminal 8. If there is power there, the junction block is bad and needs to be replaced.

I have to take my wife to the airport. I'll be back this afternoon to check on your progress.

Customer: replied 6 months ago.
With key on and brake depressed there is no power to any terminal on the back block. If I plug terminal in all tail lights except the brake lights work.
Expert:  Juan Crespo replied 6 months ago.

I don't understand; how can there be no power to any terminal on the Blue connector, yet the tail lamps work when you plug it in?

Also, that connector in the picture looks to be dirty or contaminated. Did you backprobe the wires to see if there was power at any of them?

Lastly, I uploaded a diagram for you showing the Orange wire feeding power to the STOP LP fuse; then a Light Blue wire going from the fuse box to terminal 8 of that Blue connector you took a picture of. Did you check that Light Blue wire for power?

Customer: replied 6 months ago.
Juan,
I think I'd like another expert.
Expert:  Juan Crespo replied 6 months ago.

Not a problem. Please don't reply until another expert responds or the site will cycle this request back to me.

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