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BOBBYSS, Master Technician
Category: Chevy
Satisfied Customers: 17088
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Chevrolet Suburban 2500: 1999 chevrolet suburban brake light

Customer Question

1999 chevrolet suburban hi brake light works- L & R brake lights do not- jiggling four way flasher does not solve: is there a separate relay for LR brake lights? new tail light circuit board installed
Submitted: 5 months ago.
Category: Chevy
Expert:  BOBBYSS replied 5 months ago.
Hello, my name is***** on the light in set up on your truck this is usually caused by the CHMSL relay under the hood. These fail all of the time and cause this.
Customer: replied 5 months ago.
what does chmsl mean and where is it attached-in the relay box?
Customer: replied 5 months ago.
why would it be center high mounted stop light (c.h.m.s.l.) relay if high mount brake light works? it is the low mount brake lights that do not work
Expert:  BOBBYSS replied 5 months ago.
When the CHMSL relay fails it interrupts the circuit to the rear brake lights. I did misread your initial post. There is a relay for the brake lights in the fuse box under the hood. It does control the regular brake lights and not the high mounted light.
Customer: replied 5 months ago.
I replaced relay but still no lower brake lights- since hi mount works- brake pedal switch must be ok- what is wire color at brake switch which goes to lower brake lights?
Expert:  BOBBYSS replied 5 months ago.
It is the white wire. This same wire provides power to the high mounted light. What you need to do is check and see if the white wire also has power at the hazard switch when applying the brakes. If not there is a break in the wire to the switch.
Customer: replied 5 months ago.
where does the white wire fork to provide power to hi mount and lo mount? at the hazard switch or elsewhere?
Customer: replied 5 months ago.
the brake light wire goes through the turn signal switch so is there anything that could fail in the turn signal switch to cause brake light to fail? is there a circuit diagram of multi purpose turn signal switch showing brake light connection?
Customer: replied 5 months ago.
Please answer final reply
Expert:  BOBBYSS replied 5 months ago.
The high mounted light does not go through the multi function switch but the rear lights do. Didn't you say you replaced this switch?
Customer: replied 5 months ago.
for future reference: please send schematic for multifunction switch that includes turn signal and and also routes lower rear brake lights- not sure why that switch should affecte lower brake lights- any ideas?

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