99 yukon denali

[weekend_carguy19]

i've had my car for about a month, and it was all fine for about a month no problems what so ever. but one day my stero stoped working i think i have a short because my windows don't work either and including my wipers too and i've checked my relays and fuses. but they do come back on some times when i'm driving down the road. i've noticed that when the road gets bumpy they willl some times come back on but it will shut back off when i turn my car off or try either my windows and wipers.. i also purchased this car through a used dealer so i was wondering if i was covered by gmc for my problem.. so if any one can help me fix this problem out thank you..

[envoyxuv]

I know exactly what your problem is. i have encountered this problem on two other 99 denali yukons like yours. All of the accessories that stop working are tied into the body control module. The body control module (BCM) supplies accessory power to all of the components you have that are turning off. I found on the last one i worked on, i could jar the side of the floor console (located between the driver's and passenger's front seats) and everything would turn on/turn off erratically.

To replace the BCM, or to even access it for that matter, you have to completely remove the center floor console, and the BCM is removed from the bottom. The last one that i did, i opened up the BCM case to see what was going on. i found that there 5 relays soldered to the BCM's circuit board. The relay that controls the accessory power is the tallest of the 5 relays. On the backside of the board where it is soldered in place, i found that one of the power supply pins solder joint was completely cracked around the pin. This causes an intermittent condition that makes and breaks the connection at the relay, causing your accessories to turn on and off while you're driving down bumpy roads. ****SIDE NOTE: this is the exact same problem that caused the wiper modules to become inoperative on these body style trucks as well*****

The way i look at it, you have 2 choices:
1) Go to your local GM dealer and spend $200-$300 on a new BCM (the price is in that neighborhood, not exactly sure), install it and be assured that your problems are over.

2) If you are electronically inclined, you could remove the BCM yourself, and re-solder the cracked joint on the backside of the relay and also be assured that you have corrected the problem, and be 200-300 $$ richer.

The first time i encountered this problem, it took me probably 2 hours to diagnose it. The second time it took about 5 minutes because i knew exactly where to look. You don't forget weird stuff like that.

Hope this helps out in some way. Post back how it goes!