# 99 Chevy Tahoe electrical issue, please help !!!



## Caity Lanham (Oct 19, 2011)

We have a 99 Tahoe, the brake lights went out and the switch in the steering column was replaced and still no brake lights. Back up lights and parking lights do work though. There is no power going to the switch for some reason.
This vehicle doesn't have any fusible links or relays, any ideas'?
Also maybe important, maybe not, in the vehicle on the dash one whole panel where the radio, temp controls there are no lights there either and the defrost switch will not work, not sure if any of this is possibly related to the brake light situation or not.
Please help any ideas' would be greatly appreciated.
C.


----------



## octaneman (May 13, 2009)

Hi Caity Lanham

All vehicles are incorporated with a body module, this module controls all the accessories on your car, it does everything from your defogger to the dome light. The module runs with ignition on or in accessories and is either bolted to the firewall or is under the dash near the fuse panel. If the module has fried it will knock out all your accessories even with ignition on. On some systems the brake switch is wired through the module, but to verify that it is you will need a wiring schematic of your vehicle to follow the wires one-by-one. 



If you know someone who's handy with meters and test lights and is familiar with a vehicles electrical system, my suggestion to you is have him/her do the following test and then report back to us. 


Test all the fuses first with a test light then use a DVOM to probe the steering switch open to ground by doing a voltage drop test, work your way around the harness to the main ground on the column and to the brake switch. To do this type of test hook your negative lead to a solid ground preferably battery ground. Take your positive lead and start probing the negative side of the steering column switch and the brake switch. Turn ignition on (engine off) and take your readings. An open ground your meter's reading will be a little less than battery voltage, this means that the circuit is open (not good a wire is cut somewhere) On a good ground the meter should read 0.5 or less. Is the brake switch grounded ? Do the same test only this time you do it on the positive side of the brake switch and the steering column switch. One thing you should be aware, whatever you do DO NOT PROBE OR PIERCE ANY YELLOW WIRES IF EQUIPPED WITH AIR BAG, doing so will accidentally deploy the bag which can cause you serious injury.


Question: 1) Why was the column replaced to begin with ?

2) After you replaced the column did you test power coming from the neutral safety switch to the brake switch ?




post back your findings.


----------



## Caity Lanham (Oct 19, 2011)

The column was taken apart to replace the brake switch, everything has power except there is none going to the brake switch or the panel where the defrost and radio is. All other lights and accessories are working.... All fuses are good as well, checking the neutral safety switch per you're advice. Thank you.


----------



## kjms1 (Jun 4, 2010)

brake light wire goes thru the turn signal switch ... thats so if you got a turn signal on that side will not get the brake light just the other side will so it will still flash since they use the same bulb


----------

