Air bag warning

[jhall]

Hi guys,

Got an air bag idiot light and a warning on the DIC of my '02 Deville. Only 18k miles and it should still be under warranty (I'm the second owner).

The problem has been intermittent - usually in the morning. Sometimes I can restart the car and the idiot light goes out. The DIC displayed a warning last week, so I'm assuming it was not a fluke problem at this point and something's up with the circuit.

I'm taking it to the dealer for a check / repair. Has anyone had this type of warranty repair on their car? Any potential pitfalls?

Any comments would be greatly appreciated.

[Logan]

Gotta air bag code? That would help..

[jhall]

Logan,

Checked the FAQ board and pulled the codes. I think DTC list from Tony H is the correct OBDII code translator for the 2002 Deville

U1000 - Class 2 Communication Malfunction

U1088 - Loss of Communications with SDM

I suspect a bad connection somewhere. Sometimes if I bump the steering wheel on the rim, the idiot light goes out quicker and the DTC display does not give the "Service Air Bag" warning.

On the other hand, maybe the computer has a problem, so I better beat a path to the dealer while it's still under the 4 year bumper-bumper warranty!

Comments appreciated

P.S. - Finished the reassembly of my '97 Deville engine (all new gaskets, seals & Timesert). Hope to attach the trans this weekend and drop it back in the car!

[Logan]

Any recent used electrical parts installed? I think there is a bulletin on those 2 codes.

It can be caused by using a different radio for example.

On the newer Cadillacs...the VIN is stored in each module. It can only be stored the first time.

If a used eBay component is used...you get a B1000 code and I think the B1088.

I'll have to look it up.

[Logan]

I was wrong...different codes in the bulletin. Here is what I thought...

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.

And there is another....

All GM Vehicles Using Class 2 Communications Diagnostic Strategy For DTC U1000 or U1255

.

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:

DTC U1000 or U1255 set current or history, with or without other DTCs

Recommendation/Instructions:

DTC U1000 Class 2 Data Link

DTC U1255 Lost Communications

These DTCs set when the control module does not receive a message that it was expecting from another control module, and does not know which control module did not send that message.

If the DTC U1000 or U1255 is set in history with other DTCs set current or history, diagnose the other DTCs first.

If the DTC U1000 or U1255 set current, this usually indicates a module that is currently not communicating or a configuration issue. For example, if the control module is configured for an option (ie: Onstar, Keyless Entry, Memory Mirrors, etc.) that the vehicle does not have, it may expect to receive a message regarding this missing feature. This would usually occur due to the control module being recently replaced and incorrectly setup.

When the DTC U1000 or U1255 is current, the module that is not communicating may not even be listed on the Tech 2 on the Diagnostic Circuit Check/Class 2 Message Monitor list.

If the DTC U1000 or U1255 has set in history without other DTCs, replacing the control module setting the DTC is most likely NOT the solution. The module that has set the code is looking for an input from another module that is not communicating. Since the module did not receive an input that it is expecting to see, it sets a U1000 or U1255 which indicates there was a loss of communications. Look at the customer’s complaint (ie: intermittent, erratic tachometer operation); this will probably be a better indication of the control module that is the source of the concern.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(All GM vehicles using Class 2 communications)

As for the U1088....not found. I did find a B0088 code....

The supplemental deployment loop #2 (RR/passenger rear side inflatable module) is a 2 wire circuit. When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM performs the following continuous diagnostic tests on the deployment loops:

Deployment loop voltage out of range test

Deployment loop resistance measurement test

If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.

Conditions for Running the DTC

Deployment loop voltage out of range test - The ignition 1 voltage is within the normal operating voltage range.

Deployment loop resistance measurement test:

The ignition 1 voltage is within the normal operating voltage range.

The RR side deployment loop is not shorted to voltage.

Conditions for Setting the DTC

Deployment loop voltage out of range test - The RR side high terminal is greater than 6 volts for 500 milliseconds.

Deployment loop resistance measurement test - The RR side high terminal is less than 2.4 volts and the RR side deployment loop resistance is less than 6 ohms for 500 milliseconds.

Action Taken When the DTC Sets

The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.

Conditions for Clearing the DTC

The RR side high terminal is less than or equal to 6 volts for 500 milliseconds.

The RR side high terminal is greater than or equal to 2.4 volts and the RR side deployment loop resistance is less than 6 ohms for 500 milliseconds.

You can issue a CLEAR CODES command.

A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following can cause an intermittent condition:

A short to ground or to voltage on either of the two sides of the deployment loop circuit can cause an intermittent condition.

Inspect the RR side high and the RR side low circuits carefully for cutting or chafing or any type of wire damage.

Wiring pigtail damage requires replacement of the RR side inflator module.

If any of the above conditions are found refer to Testing for Intermittent and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This step checks the RR/passenger rear side inflatable restraint module (air bag) in-line connector.

This step checks to see if there is a malfunctioning RR side inflatable restraint module (air bag).

This step checks to see if there is a short to ground in the RR side high deployment circuit.

This step checks to see if there is a short to ground in the RR side low deployment circuit.

This step checks to see if there is a short to voltage in the RR side high deployment circuit.

This step determines if there is a short to voltage in the RR side low deployment circuit or if there is a malfunctioning SDM.

This step clears all SIR DTCs.

[jhall]

Hi Logan,

Thanks for the info. No parts have been installed since I bought the car last November. The problem started late last week, so I suspect a poor connection or faulty electronics somewhere.

Called the dealer this morning and will probably drop it off tonight for an AM service tomorrow.

I'm hoping the work will actually be covered by warranty. It looks like it will take a while for them to troubleshoot.

[jhall]

Hi all,

Here's an update:

Took it to the dealer today.

They pulled the codes (U1000 - Class 2 Communication Malfunction and U1088 - Loss of Communications with SDM) and took about 2 hours to replace the SDM module. Based on what I could see it was located under the passenger seat or the rear part of the center console. The tech had the seats all the way forward.

All parts / labor was covered under warranty

Some interesting stories I overheard while waiting:

A guy needed some AC work on his Caddy. He had a leak at the dryer and the blower motor was whacked. They quoted $1000 to replace the parts and recharge the system - about half of the cost was the blower replacement - about $450.

Another customer had a radiator leak and someone replaced the coolant with the "green stuff". The service rep told him that he needed the system flushed and the fluid needed to be replaced with the "orange fluid" so the engine would not corrode (partially correct). He failed to mention the silicates that come with the "green stuff".

The dealer put new tires on another customer's car a few months ago and did not align the front end because it "was not requested". Customer was back in because of tire wear. No help for her - she now has poor tire wear and must pay for an alignment.

I've had past experience with this dealer and keep a close eye on what they say and do.

[KHE]

A guy needed some AC work on his Caddy. He had a leak at the dryer and the blower motor was whacked. They quoted $1000 to replace the parts and recharge the system - about half of the cost was the blower replacement - about $450.

I'm beginning to think about opening an A/C shop.....

[Logan]

After you mentioned that no used parts had been installed....I suspected the air bag SDM. AKA the black box on CNN and other media sources...

Its about a $500 component. So that warranty may have been worth the price.