best_vette_yet

Here is the short story: 2000 Vette with Passenger on/off switch

Wrecked vette blew both bags.
Bought complete set of bags and the Air Bag Sensor (SDM Module) off a 2001
vette.

I installed the Passenger bag only. Then I turned the bag off with the switch in the glove box. Just for safety I left the OLD SDM module in the car and took a voltage reading from the steering wheel with no bag hooked up. The SDM module was sending 3 volts to the steering wheel with the ignition key on. Remember this was the module involved in the wreck that triggered the bags in the first place. I was told they are a 1 shot deal and need replacing after they blow the bags.

Now I install the new SDM module that came with my new airbags and repeat the drill to make sure I don't have a bad module and blow my new bags. I get the same exact 3 volts from the new module that I got from the old module. Question: Does anyone know what the voltage to the steering wheel is supposed to be with the key on and a known good SDM module????

I don't want to blow these new bags!

best_vette_yet

ttt

Surely someone has a little info they can share on this.

ersatz928

I suspect that the 3V reading, without a bag connected, is normal. This is the open circuit test voltage that the SDM puts out to test if the airbag ignitor circuit is good, when you first turn on the key (airbag self-check). A good airbag has a low resistance and would drop this voltage to a much lower level. You can verify this by connecting a 5 ohm resistor across the airbag terminals (the wires that come from the SDM). You will then see probably less than 1V when you turn the key ON, during the self-check. Look in the Factory Service manual to verify the normal resistance range of a good airbag ignitor. This is the value that the test resistor should be. I am only vaguly recalling that it is about 5 Ohms.

stano

LAPD has a GM tech...maybe they could help

best_vette_yet

Anthony,

Thanks for the info. I had heard most of what you say about the 3V from a local tech. I'm trying to get as much info from everyone that will help out and then try to piece it all togeather. These darn things are so expensive I don't want to screw up.

My 3 volume G.M. tech manuals say nothing about the 5 ohms. From reading everything I get the idea they don't want anyone but G.M. techs to know what is going on with their air bags. It's understandable these days.

Thanks again,

anyone else?

Logandiagnostic

You have more problems then you can imagine. Even a Tech2 cannot fix this.

There is a GM TSB on this issue....

DTCs B1001, B1271 or B1780 Set When Replacing/Reprogramming Other Modules
1999-2003 Passenger Cars and Trucks

with Class 2 Serial Data Communication Between Modules

This bulletin is being revised to add model years and reflect changes in the Tech 2 procedure and filing classification. Please discard Corporate Bulletin Number 99-06-03-010A (Section 6 -- Engine).

Class 2 Serial Data Communication allows control modules (i.e. the Powertrain Control Module (PCM), the Body Control Module (BCM), the Dash Integration Module (DIM), the Instrument Panel Cluster (IPC), the radio, the Heating, Ventilation and Air Conditioning (HVAC) Controller, and the Sensing and Diagnostic Module (SDM) to exchange information. This information may be operational information or identification information. Among the identification information exchanged and compared within these modules is the Vehicle Identification Number (VIN). Typically the one module, the master module, broadcasts the VIN and all the other modules compare the VIN stored within itself. When the broadcast VIN does not match the VIN stored within the SDM, the following actions occur:

DTC B1001 Option Configuration Error is set and deployment of the airbags is inhibited.
DTC B1271 or a DTC B1780 Theft Locked. The VIN information is also used by the radio. When the VIN does not match the VIN stored within the radio, DTC B1271 or DTC B1780 is set and the radio is inoperative.
Additionally, the master module will compare the SDM's part number (last four digits) to determine if the correct SDM is installed in the vehicle. If the SDM is the wrong part, a B1001 will also set.

This situation may occur when a vehicle is being repaired. When a PCM or a body control type module is replaced, the VIN information must be programmed into the replaced (new) control module. A module which has had VIN information entered into it (for example, one taken from another vehicle) cannot be reprogrammed. VIN information can only be entered into new modules. The ignition must be ON in order to program the control module. Since the VIN information is broadcast when the ignition goes to ON from any other ignition switch position, DTCs may be set in the SDM and/or the radio. Therefore, always follow the specified control module replacement procedures.

After completing the repair, turn OFF the ignition for at least 30 seconds.
Turn ON the ignition and check for DTCs using a Tech 2® scan tool. If DTCs B1001, B1271, or B1780 are present with a history status, DO NOT REPLACE THE SDM OR THE RADIO.
Clear the DTCs from all modules using the Tech 2 scan tool.
Remove the Tech 2® from the vehicle
Ensure the proper operation of the SDM by turning OFF the ignition and then turning ON the ignition. The air bag warning indicator should flash seven times and then go OFF.
Refer to Corporate Bulletin Number 99-09-41-001 for additional information regarding proper reprogramming of the new/replaced module.

Clearing codes from the other modules is part of the replacement and reprogramming procedure for the replaced module. The repair is not complete unless all codes have been cleared from all modules.

That basically wipes out using any eBay parts....
http://www.airbagcrash.com

Logandiagnostic

That should say...

http://www.airbagcrash.com

Logandiagnostic

I should add....

I think the bags will work ok....

But I think you will need a new GM SDM module to get it all to work.

http://www.airbagcrash.com

best_vette_yet

Hey Log,

Thanks so much for the info. I will try the module and bags this week to see what happens. I'll pull the codes right now to see what I have for history codes as well. Then clear everything with my autotap program.

Thanks again,

Logandiagnostic

If your interested....if you have the original deployment airbag SDM....we have the equipment that can download the deployment data. The Vetronix CDR. Dealers dont even know about this equipment.

Most GM airbag SDMs have 5-10 pages of data recorded during a deployment or even during a 'near' deployment event.

The current US record download speed is 141 mph. It was a Corvette racing a Mercedes Benz. The Corvette hit a Jeep cutting it in half. 4 people killed in the Jeep. The Corvette driver survived.

Our highest download is 97 mph. 2001 Cavalier. Unbelted male. He survived.

See-
http://www.airbagcrash.com


Logandiagnostic
http://www.airbagcrash.com
http://www.logandiagnostic.com

Heretic

Cool info on your website.


Common belief is that pre-deployment data was stored only in 1999 and newer, and only in some models. Is this not true?

Logandiagnostic

That is correct. Most '99 and newer airbag SDMs record both 'near deployment' and deployment crash data.

Near deployment recordings will go away after 250 cycles. Also tapping or mishandling the SDM module can write over near deployment records.

Deployment data is hard recorded into the SDM module. It cannot be erased.

http://www.airbagcrash.com


Logan Diagnostic

best_vette_yet

Well Logandiagnostic,

You were right, I got the dreaded B1001 DTC today when I finally turned the system on. I guess there is not much to do now except buy a new SDM module. If I understand correctly it's not the VIN number but instead it's the last 4 digits of the part number that must match my original SDM. I need to be sure before I order the new SDM module. Do you know? Is it the VIN number or the Part number? Thanks.

bartek_72

Have you changed your SDM already? I am before changing Airbags and SDM and I am very curious what are your experience with changing airbags, SDM, reprogramming etc.

natmyst

I have a 2004 C5 - replaced blown bags and have B1001 and B0051 codes. Getting ready to replace SDM.
Dis it all work for you after replacing all 3, without reprogramming?