Infamous Service Air Bag message and light on 2004 GMC Yukon XL

testdepth · March 21, 2018

2004 GMC Yukon XL SLT with 5.3 Flex and 165000 miles. Service air bag light and message have been coming on and off for a few weeks. I purchased a scanner to read the SRS system and it showed code B0077 for the driver side impact sensor. I replaced that sensor 3 days ago and have not driven the truck since. Went out this morning to turn it on and the light and service air bag message are back. I have not been able to scan it yet but I assume it will give me the same code.

Is there something specific that will cause this? I don't see how an impact sensor in a door would go bad just sitting there.

The only other possibilities I can think of are a bad ground somewhere or a problem in the doors wire harness from opening and closing the door over the last 12yrs we have owned it.

Doug_Scott · March 21, 2018

My experience predates current technologies, but, it used to be pretty common for the bundle of wires that run from the cab to inside the door would break some wires over time. Almost always only the drivers door, likely due to it being used every time the vehicle gets used. Sometimes simply flexing the bundle would make and break the connection, making it easier to detect. Not sure the light would go out right away for the air bag though.

testdepth · March 22, 2018

Found and answered my own question so here it is for someone else to use.

DTC Code B0077 is the drivers door side impact sensor. The problem is the way GMC installed the wires to the plug for the sensor. These two wires are tightly twisted (see picture) the entire length of the wire run for the impact sensor. It runs through the door harness that way. Then add the stress of opening and closing the door for years and the wire nearly popped in half. When I pulled the grommet out and unraveled the electrical tape I found the wire and barely tugged it and it pulled right apart. Made the repair with a new wire and no more Service Air Bag message and the light is out. The broken wire in the photo runs from the side sensor through the door to the connector under the kick panel on the left of the drivers foot. It was broken right where the bend is in the door grommet.