GM Tech 2 shorting CANbus?

[antoniopetruzziello]

Hello,

I just bought a 2007 GMC Yukon SLT. When I got it, the airbag light was on, so I brought it to a friend that has a SnapON scanner. The scanner showed a B0090 - Rollover Sensor Performance - Erratic. I checked the wiring for the rollover sensor with a multimeter according to the AllData documentation, which was fine, so I replaced the rollover sensor. I brought the truck to a dealer to do the ROS setup procedure, but the code was still there. So I ordered a new SDM and I ordered a GM Tech 2 Clone from ebay, so that I didn't have to drop $125 at the dealer each time I want to test / reset.

However the Tech 2 is giving me some strange behavior. The Tech 2 works for some applications; it can connect to the ECM and read DTC and live data, as well as communicate with the BCM and control all of the lighting and test the horn. It canNOT communicate with the new SDM to do the SDM setup procedure or communicate with the Radio nor a handfull of other modules. I have a feeling that the CANDi module is causing the bus that the SDM is connected to, to ground out. I say that, because when I hook up the OBD II connector with the CANDI module to the Tech 2, the truck immediately loses connection with several modules, such as the 4 wheel drive module, Ignition switch module and the Radio and amplifier module. While the CANDI module is connected, none of the gauges work, the starter won't crank, and the radio won't turn on.

I'm looking for answers to one of a few things. It's obvious that I'm affecting one bus and not the others. What bus has the BCM and ECM, and what bus has the SDM and RADIO?

Also, does anyone have the pinouts for the GM Tech 2, so that i can test the tester and see if there is a short within one of the cables, adapters, or connectors?

Thanks!

 

[BRUTUS_T_HOG]

Tech 2 clone. Case closed.

 

[antoniopetruzziello]

Ok, I opened up the CANDI module and I found two contacts bridged, causing the CAN bus to short to ground. I fixed that and I now have the Tech 2 scanner communicating with the Truck. I was able to get the scanner to do the Rollover sensor setup procedure, however the SDM setup procedure won't work. The scanner says that programming is required, however when I hit the program button, the text never changes from 'Required' to 'Complete', like the scanner says it should.

I am doing the program with the Key on and Engine off, and I'm going to try disconnecting the battery for a while and try again. Does anyone else have suggestions on how to get the setup procedure to work?

Thanks!

 

[BRUTUS_T_HOG]

Is B0090 still setting?

It looks like you have to set up the SDM key from the BCM and program the SDM


If DTC B0090 is set, refer to DTC B0090.
Ignition ON, program the SDM. Refer to Service Programming System (SPS).
In the BCM Module Setup menu, select Setup SDM Primary Key in BCM. Follow the scan tool on screen instructions.
In the SDM Module Setup menu, select Setup SDM. Follow the scan tool on screen instructions.
Cycle the ignition from OFF to ON. Verify no DTCs are set. If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

 

[antoniopetruzziello]

Thanks for the reply! I've got the airbag system fully working now! After trying to unhook the battery for a while, which didn't help, I tried the previous SDM, cleared the DTCs and now I have no codes!

My thinking is that the whole problem was in the Rollover Sensor, as I first suspected from the B0090 code. After swapping the ROS, I took the truck to the dealer to do the Rollover Sensor setup procedure, which they said they did, but that it didn't fix the problem. I asked them specifically to repeat to me that they had completed the setup procedure, and they said yes.

However once I had my Tech 2 scanner working did the Rollover Sensor setup procedure and put back the original SDM, the truck is working. That says to me that the dealer didn't actually do the Rollover Sensor setup procedure.

I still don't have an explanation as to why I was unable to do the setup procedure for the new SDM, but I have a working truck now, so I'm happy!