air bag

[airmike]

I have an air bag light on. I am assuming something I did when removing the engine caused it.

I have code b1126. There are a couple other codes for my suspension that I am not interested in at this time.

Can I reset it somehow? I run the codes and reset them a couple times now and the air bag light does not go off when I reset the codes. The service engine light will go off for a while, then reset, but the red air bag light never goes off.

If a ground or connection is likely, I would appreciate a location to start. I tried to clean all connectors and grounds before putting it all back together.

One other thing.....I cannot figure out how to use the search productively!!! I have went into different sub forums and then type in "air bag" in the search and NEVER manage to get straight to anything air bag specific.

[Cadillac Jim]

B1126 Driver Deployment Loop Open

I'm assuming that this is the 1999 STS. My DVD doesn't go back that far and my oldest STS FSM, for the 2002 model year, doesn't have that DTC. My 1997 FSM does, but there was a platform change for 1998 that may affect applicability of this FSM to that particular problem in your 1999 STS. With those caveats, this is what I have.

If it's CURRENT or comes back immediately after it's cleared, you have an open circuit or intermittent connection in the wires between the SDM and the air bag in the steering wheel, or the sliding steering column connectors are going bad or need to be cleaned. Since this happened when you pulled the engine, I'm assuming that it's a wiring problem, probably at the SDM connector. In my FSM, its the WHT and DK GRN wires on terminals 10 and 9, respectively.

[Logan]

My service info goes back to 1998. Anyway, the 1999 STS service manual shows B1126 as driver deployment loop open.

[Cadillac Jim]

What does the 1999 FSM say in the general troubleshooting paragraphs before the detailed procedure table?

[Logan]

When you first turn the ignition switch to the ON position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures Ignition 1 voltage to make sure it is within its respective normal voltage range. Then the SDM proceeds with the Deployment Loop Continuity test. During the Deployment Loop Continuity test, the SDM measures the voltage difference between Driver Frontal High and Driver Frontal Low.

Conditions for Setting the DTC
• The voltage difference between Driver Frontal High terminal 10 and Driver Frontal Low terminal 9 is more than or equal to 426 millivolts.

• The malfunction must be present for at least 500 milliseconds during one of the following tests:

- Deployment Loop Continuity

- If the malfunction is detected in this test, the Resistance Measurement test will not be performed.

- Continuous Monitoring

Action Taken When the DTC Sets
• The SDM sets a Diagnostic Trouble Code (DTC).

• The SDM command the instrument cluster (IPC) to turn ON the AIR BAG warning lamp.

Conditions for Clearing the MIL/DTC
• Current DTC

The voltage difference between Driver Frontal High terminal 10 and Driver Frontal Low terminal 9 is less than 426 millivolts for 500 milliseconds.

• History DTC

- You issue a scan tool Clear DTCs command.

- Once 250 malfunction free ignition cycles have occurred.

Diagnostic Aids
The following can cause an intermittent condition:

• A poor connection at the inflatable restraint steering wheel module column connector terminals A and B.

• A poor connection at the upper inflatable restraint steering wheel coil connector terminal A and B.

• A poor connection at the SDM terminals 10 and 9.

• An open in CKT 347.

• An open in CKT 348.

An intermittent open in the inflatable restraint steering wheel module coil could also set this DTC. In order to test for a bad inflatable restraint steering wheel module coil, clear the DTCs, then turn the steering wheel back and forth with the ignition switch in the ON position. If the AIR BAG warning lamp comes ON and DTC B1126 has set again, it is likely the inflatable restraint steering wheel module coil is malfunctioning.

The diagnostic table directs the technician to note the scan tool value of Driver Frontal VDIF. Comparing the value of Driver Frontal VDIF can be helpful in determining if an intermittent condition exists.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to General Electrical Diagnosis in Wiring Systems. When a wire, connector or terminal repair is requested, use J-38125 Terminal Repair Kit and refer to Wiring Repair .

[airmike]

Logan, having read this, I am wondering if you need a scan tool to clear the code? or 250 malfunction free ignition cycles must occur. Meaning I can't clear that with my dash buttons? Then my next question is what is a ignition cycle? Does that include starting the car or just running? Something I am going to research while awaiting a response.

[KHE]

Check the sensor at the front - it should be near the radiator support - it's possible you forgot to plug it back in after the engine R&R.

[airmike]

I have checked it but i guess I will unplug and clean the connector. The sensor doesn't have a necessary location approximate to anything does it? I feel like I replaced it to approximately where I removed it.

[Göran W]

Reading this makes me wonder: Is it possible that this occur from a temporary "ign on" before everything (!) is replaced?

[airmike]

Checked, re-cleaned and reset all codes. No change. Removing the SIR fuse is the only thing I intentionally undid in this whole process. I would like to know that it should have reset itself or by me resetting the codes via dash buttons before wasting a lot of time chasing wiring failure

[airmike]

I also unhooked wires under the glove box at one time, I believe I will check those connectors next.

Could I have hurt something in the steering column when removing the cradle? I did forget the bolt in the column, and had to remove it after once trying to let the cradle down. I did not let the entire weight of the cradle hang from that bolt, but of course it did get a certain amount of strain while I was figuring out what was holding me up.

[airmike]

Cadillac Jim, reading this

" If it's CURRENT or comes back immediately after it's cleared, you have an open circuit or intermittent connection in the wires between the SDM and the air bag in the steering wheel, or the sliding steering column connectors are going bad or need to be cleaned. Since this happened when you pulled the engine, I'm assuming that it's a wiring problem, probably at the SDM connector. In my FSM, its the WHT and DK GRN wires on terminals 10 and 9, respectively.

I have my cd opened and the SDM appears to be under the passenger seat. I will be checking there to the wires under the glove box.

[Logan]

Logan, having read this, I am wondering if you need a scan tool to clear the code? or 250 malfunction free ignition cycles must occur. Meaning I can't clear that with my dash buttons? Then my next question is what is a ignition cycle? Does that include starting the car or just running? Something I am going to research while awaiting a response.

I think your confusing codes with crash data that is stored in the air bag SDM. A non-deployment crash file will disappear after about 250 ignition cycles.

To the SDM...a ignition cycle is 'key on'...readiness lamp flashes 7 times = 1 ignition cycle.

[Cadillac Jim]

I'm sure that these DTC's are cleared from the A/C buttons. If in doubt, cycle through the SDM module options with FAN DOWN and ask for the codes after you clear them and see if they are back already.

[airmike]

Ok thanks guys. My problem is with the reset. I cleared the codes and they disappear and the service engine soon light goes out, but the red air bag light (by its self) never goes out. So I wondered if it needed other attention, however the b1126 returns soon so wiring gets the attention.

[Cadillac Jim]

The fault that throws the B1126 will keep the air bag light on.

[airmike]

Haven't found the problem yet, but haven't had time either. I remembered something else though, all of the steering wheel controls no longer function either. I am wondering if that is connected? I removed the SIR fuse while doing the project and no other fuses, and that fuse is replaced and in working order. I am headed out to the garage now and will check back for any ideas in a bit, thanks to all

[airmike]

Just checked all under hood and under the back seat fuses with multi-meter, all good. The under hood cover diagram doesn't match the actual fuse block. Am currently researching that dilemma. I didn't find a relay that I recognized as pertaining to the steering wheel functions, to swap.

[airmike]

I should restate...the steering wheel driver memory, seat adj, tilt, telescopic etc. do work. Just the vol, sel, fan, temp buttons on the face of the steering wheel don't work.

[Cadillac Jim]

Again with some trepidation, I'll look at the 1997 FSM. They have the schematic of the steering wheel controls on page 8A-152-0. The lights are LEDs, which may be why we never hear about some model years needing the bulbs.

There are threee fuses involved, both in the STEERING COLUMN FUSE HOLDER, which isn't on the component locator chart. One, a 2 Ampere, with power from the interior lamps dimming, powers the bulbs/LEDs. The other, also a 2 Amp, powers the switches themselves. In the trunk compartment fuse block, the 20 Amp CLUSTER FUSE powers the switches.

Both the power in lines go through SIR coil assemblies. Both are grounded through SIR coil assemblies too. The switches are grounded to the instrument panel cluster IPC module. The switches short across resistor arrays and the IPC tells which one by measuring the resistance. The left and right switches are in parallel so if it works for both at once it isn't simple but I suspect it only works when one is used at a time.

The input and output of the air bag coils is labeled MOLEX CONN, near C202, which is near the base of the steering column. Inputs are terminals A (switches) and B (LEDs), and outputs are terminals C (IPC) and D (ground).

I would look at connector C202.

The TROUBLESHOOTING HINTS says to check the CLUSTER FUSE and to make sure that ground G204 is clean and tight before you start. G204 is located at the "Left hand front of the passenger compartment, behind the kick panel." Figure 22 on page 8A-201-23 shows G204 to be to the side panel near the hole where the nylon wiring harness plug attaches to the body. C202 is the huge connector for all the wires going up into the steering column.

If all the lights in the switches are also out, the Molex connector (slip rings, I presume) isn't connecting, or he air bag coils are unplugged.

[airmike]

I have come to the conclusion that the wiring has been damaged to the SIR. I have been researching, and find that if you turn the steering wheel with the wheels disconnected you can damage it and the steering wheel controls not working can be a symptom. I definitely did do that when it was all apart. So my question now is, can anyone tell me where said damage is likely to occur? I am figuring its in the upper part of the column? Then assuming that is the case, is that repairable? I have been reading the fsm and it states: to only use correct connectors etc...

I am not wanting to assume I can test the integrity of each wire with an ohm meter. I would hope for advice from more experienced members. If its likely that I am going to need to replace the part, I would like to have it here before jumping in. Of course I would like to NOT buy a part if repair is feasible.

The diagnostic tree includes using a tech II which I do not have available. I also don't know how else to test the system. I would assume the tech II would still lead me to testing the wires or just replacing the module.

Once again thanks to all for any help.

[Logan]

"I have been researching, and find that if you turn the steering wheel with the wheels disconnected you can damage it and the steering wheel controls not working can be a symptom. I definitely did do that when it was all apart."

That little nugget of of information explains what happened. Sounds like the air bag clockspring is damaged. Basically it is a wound coil of flexible printed circuit board...that allows rotation of the steering wheel while at the same time allowing circuitry to work at the steering wheel. (air bag, horn, radio controls etc)

When new...the clockspring assembly has a keyed retainer. Remove the retainer and the assembly can rotate maybe 5 turns in either direction. Much beyond the 5 turns....the flexible circuit board inside will be damaged. The clockspring is installed with the front wheels straight ahead...then the keyed retainer is removed.

To replace...the air bag and steering wheel will have to be removed from the steering column.

I attached a pic of a air bag clockspring.....this one happens to have a clear housing so you can see the flexible circuit wound up inside. I have never seen a clear one before myself...most are all black with yellow air bag warning stickers.

I also added a pic of the 99 STS version. GM calls it the SIR coil rather then clockspring...

[airmike]

I found a used steering column for $60 and am planning on taking the clock spring from it to use in mine. Is there a way to check the used one before I take my car apart to make sure it is in working condition. When I went to pick up the used column, the steering wheel was free to spin, and I have no idea if it has rotated enough to ruin it. The salvage will exchange it if defective, and state they have no way to check it. I don't really want to do this over and over until I find one that is working, or have my car out of commission for extended time period again.

[Logan]

Any steering column that is in a free spinning condition the SIR coil is suspect. The SIR coil is a fairly delicate component...and easily damaged.

I would recommend getting a new one vs. a salvage yard one. It is rather involved swapping one out. I attached a pic from a '96 or 97 that was getting a new turn signal switch (10 year old picture..). You can see the SIR coil hanging there with the blue tape holding the position. On the earlier cars the SIR coil wire runs all the way down the inside of the column and connects at the base of the column.

Your '99 the coil swap would be easier then the '96-97 shown.

[airmike]

Logan, I am suspecting that it cannot be checked with ohm meter? since you didn't offer that up as a choice.