My 2000 GMC Jimmy SRS light has been off/on for the last 4 months. I did not have a scanner the could read the SRS codes so I purchased one from Harbor Freight. The scanner found SRS Code B0036. My factory service manual indicated that this was a possible short to ground or a faulty impact sensor. I assumed it was an impact sensor and pulled a right/left sensor from a junkyard. The SRS light would still light intermittently after I replaced the sensors. I decided to simplify installing the sensors by installing 1/4-20 threaded inserts and used stainless steel truss head screws to mount the impact sensors. I got serious about trouble shooting the fault IAW the service manual. I checked all the wiring for continuity from the drivers side connector to the passenger side connector. I checked the wiring from the C109 (6 way connector) to the drivers side connector. (4 Pin). I checked the ohm readings from the drivers side (Pins A & C) to the passenger side impact sensor and the readings were 988 Ohms. When I attempted to read the complete circuit for C109 pins A & B, I would either get no continuity or high ohm readings. I made up two jumpers to bypass the drivers side impact sensor by jumping pins A & B and pins C & D, This would allow the the circuit to be complete without going through the drivers side impact sensor. Once I did that the SRS light no long stayed on after start up. Therefore I knew I did not have an SDM problem or a wiring/connector problem. I pulled another drivers side impact sensor at the junkyard and checked pins A & B, C & D for resistance and had 0 Ohms.. The original and 1st junkyard sensor was either measuring open or high ohm readings across the same pins. Once I installed the sensor and turned the key on the SRS light flashed 7 times and stayed off. (Correct operation) The original sensor had an internal short and the 1st junkyard sensor was bad from the get go.

 

Great writeup.

I'm looking at possibly another bad SRS sensor going bad on my Blazer. I've wondered if the odds of getting a bad sensor from a wrecking yard will be going up.

What was the model number of the HB code reader? Can it also do the ABS bleed?

 

HF Model Zurich ZR13. If you go to pull a sensor from the junkyard bring a multi-meter with you so you can check the resistance across the pins . Drivers side: (4 Pin) Y-Y = 0 ohms, B-B = 0 ohms, Y-B = open., Passenger side: Y-B = 988 approximate as it is a 1K resistor. My original and junkyard passenger side both measured 988 ohms.

 

I am not sure about the ABS bleed. HF has a link to the PDF manual. The cover has ABS listed but I am not sure what it can or cannot due. I believe it only reads ABS codes. Nothing in the manual ref. ABS bleed.