History: 2006 XJ8 Base

Jan 2011 front end crash, no passengers, driver airbag delpoyed, driver seatbelt buckle pretensioner fired,
all three rear seatbelt pretensioners fired.
July 2011 Sent RCM to Myairbags to have crash codes cleared and module reset. All three seatbelt pretensioners repaired
and driver seatbelt buckle pretensioner repaired.
July 2001 Using two flameproof 1/4 watt 2.4 OHM resistors in place of two stage driver airbag, allows RCM to be spoofed into
thinking driver airbag present while I wait for the correct replacement airbag.

Using Auto Enginuity ST-06 OBD PC based scanner with latest Jaguar specific module, I am able to clear RCM related codes. I
proved this with the belt pretensioner codes anddriver airbag codes.

After multiple attempts, including disconnecting battery cable overnight, resetting RCM codes and cycling ignition I cannot
clear airbag Flash Code 17. The AE scanner shows B2291 with and isntead of displaying a PID it states specific module
condition Passenger Sensor 4 fault. This implies PID 24 ( Passenger OPS Sensor 4 ( outer headliner /B pillar) Sensor fault.
However I think this is red herring. The Jaguar Service Flash Codes & PID Code defintions table, for Flash Code 17 it lists
possible PID codes and 24 is listed first. Talking the AutoEnginuity (AE) technical service folks, they walked me though live data
stream capture steps and could connect to the RCM and display the actual values the module is sensing from the pretensioners and airbag
squibs and my 2.4 OHM resistors in place of the driver airbag. Using the AE scanner tried to connect to the passenger seat module
and it could not talk to it. Checked #29 Fuse and it's good... same fuse feeds the RCM, Passenger airbag light and Occupancy Sensing module
under the pasenger seat. I am assuming the AE tool is trying to connecting with the Passenger Sensing Module but cannot. The AE techs tell me
thier Sw cannot communicate with that module so it is impossible to pull the codes. Their tools should not be posting B2291
Sensor 4 fault but rather it should be posting B2291 Passenger OPS Communication Fault which is a PID 29. I think they listed
the first Fault Description instead of the last one. I'm still wrestling with AE to see if they can correct that.

Here is the mysterious part. When you examine the schematics, the passenger weight pressure sensor feeds the Passenger seat Weight Sensing module
which is a small black module under passenger seat with 10 pins.. 2 of which are a CAN network connection to the RCM. The RCM drives
the passenger airbag light which illuminates when the pass airbag is disabled. With the car running, while sitting in the driver seat, I can reach over
and buckle the passenger seatbelt - with the passenger seat empty - the passenger airbag light turns ON. Unplug the passenger seatbelt buckle and light goes OFF.
This is repeatble. While leaving the ignition on and car running, if I sit in the passenger seat and buckle the seatblet, the pass airbag light goes OFF.
If I lift myself off the seat, the pass airbag light
goes ON. This tells me the Passenger seat weight sensing module is feeding the Occupancy Sensing Module which in turn is communicating
with the RCM which cycles the pass airbag light OFF and ON while I sit and then lift myself from the passenger seat. I assume this uses
the CAN network for transfering this information. I understand that CAN is a serial protocol meaning signals are sent on one line and
received on another. They are twisted pair wires and are depicted so in the schematics with the Infinity symbol. In any case, the schematics
show a CAN path between the RCM and Occupancy Sensing Module and a CAN path between the Occupancy Sensing Module and the Passenger
Seat Weight sensing module. The seat weight pressure sensor information is indeed working properly. But why can't my AE scanner communicate
with the passenger seat module? I reseated all the connectors under the seat and to the RCM.

Can someone with AE scanner test whether their scanner is able to connect to and retrieve live data from the passenger seat module?
Would it make sense to try another Occupancy Sensing Module ( found replacement on ebay ).?
If I replace Occupancy sensing Module, do I really have to recalibrate the weight sensing module and is that only done by Jag service?

Could the Occupancy Sensing Module allow passenger weight sensing information to flow out of the CAN but not be able to take CAN related commands
to drive the Spaial sensors? In other words could part of that module be bad? How can it allow info to flow from it, but not be able to
have CAN related command sent to it?

Any pointers would be helpful.
Bob

 

The passenger seat may need to be configured as 'seat cover replacement procedure' with WDS or IDS.

I am including Tech Line help tips from years ago that have some info you might find helpful.

Also a parts TSB.

bob gauff

 

thanks for the pubs bob. These and the other you've posted are serving to to of high value. thanks again. On the subject of CAN network protocol. I'm thinking that the Passenger Seat Wight Sensing module simply broadcasts it's metrics over the CAN network. And since that module connects to the Occupancy Sesning module via CAN network, the data stream sent by that module is basically on the CAN Network BUS at that point and the the RCM deciphers it. So I'm thinking the Wegith Sensing module sends unsolicited metrics by broadcasting it's unique data stream and the RCM is seeing it. In my mind to see the CAN network as a typical BUS and the Occupancy Sensing module simply serves as a conduit essentially passing it through it's CAN network connection to the RCM. So the question still remains, why can't the RCM send query bit streams to the Occupancy Sensing module. The CAN Network is use by Jag appears to be a setup where one wire of the twisted pair is for sending, while the other is for receiving... Which would explain why the Passenger Seat Weight sensing module dishes it's metric out the transmit CAN wire and the RCM recognizes it and interprets the bit stream. Does anyone know how the JAG CAN network operates in this regard?
Thanks, Bob

 

A bit more light reading for you...

 

Great upload!!!!! I was going to get my Advanced Electronics and Multiplexed Circuits Student Guides copied into .pdf so I could upload the entire guide(s). That is a great section of the Multiplexed Circuit study guide.

bob gauff

 

Whoa! Hold up, Bob. These new SRS systems can be a challenge; and with the new ISO14229 standard code format, generic scantools and flash codes don't always tell the whole story. Your B2291, Flash Code 17, deals with the Occupant POSITION system, not the Occupancy SENSING system. The latter deals with the weight of the passenger, so it can turn off or depower the passenger airbag. The code you have is for the POSITION sensing system, which is there to sense the passenger leaning forward for instance. That's to prevent the airbag from deploying if your face is in front of the airbag. The veneer panel covering the airbag could decapitate someone when it deploys. That system uses ultra-sonic sensors to monitor the passenger, two in the roof, one in the "A" pillar and one in the center stack. They work kind of like sonar, that way the thing can keep track of where the passenger is. The B2291 says THAT system has a fault, and there are actually two more digits to the fault code that your scantool can't see. It would be something like B2291-24. The 24 would narrow the fault down to a sensor, a calibration fault or a communications fault, for instance. So a trip to someone with the Jaguar IDS/SDD may be in order so you don't just throw money at it.
Something else I use that helps quite often is an ultra-sonic vacuum leak or wind noise detector. Those sonic sensors constantly emit clicks and listen for the bounce and return; using the detector [basically a sensitive microphone] the sound of the sensors can compared to one another. If one sounds different from the others, that's a bad sensor.

HA! I found the bulletin I was looking for, see if this helps!

Good luck!

 

Steve, thanks for jumping in here. it's interesting that you say " The 24 would narrow the fault down to a sensor, a calibration fault or a communications fault, for instance..."
I was on the phone yesterday with AutoEnginuity engineer who worked with Jag to build out the Jag Specific module for their OBD ProScan tool. Their tool reports B2291 -24 ( Passenger OPS Sensor 4 fault). I argued that it's misleading and it should be report B2291 - 29 ( Passenger OPS communication fault) becuase when using their tool to specifically connect to the "Passenger Seat Module" it fails to do so. They held their position that they can't make up codes, but he couldn't prove to me that their tool was actually retrieving a PID 24.. Coincidentally, the list PID codes for FlashCode 17 w/DTC B2291 starts with PID 24. Coincidence? Maybe.

Failure of RCM to communicate with the Passenger Seat Module indicates the communication from RCM to OCS Module ( occupant sensing module ) is not functioning, yet the the passenger seat weight sensing module is broadcasting accurate metrics and it's wired ( all six conductors) through the OCS Module to the RCM and the RCM is correctly handling those signals by cycling the Passenger airbag light accordingly when the passenger seated is empty with belt buckled (light ON ) or occupied ( light OFF).

There are no Indy garages around here with IDS, so I have to take to the dealership. I had my RCM clear of hard crash codes by MyAirbag in Georgia. The AE ProScan tools is capable to clearing RCM related DTC's and I did so after reinstalling the RCM and seatbelt pretensioners. I am down to this Flash Code 17 B2291 ( supposedly PID 24)
. The bulletin says ..
"NOTE: If a fault is identified within the Occupancy Classification System (OCS) Module,
passenger seat weight sensor, or passenger seat weight sensor harness, ALL of these
components MUST be replaced as a complete kit."

YIKES! what is that going cost?
What is the likely outcome if I take to the dealership? Could it be the RCM, or the OCS Module and if it's the OCS, sense the weight sensing bladder is working, does that mean it's excluded from the list of parts to be replaced if the OCS module is replaced?

Bob

Snippet from Tech Bulletin with Flash Code 17 DTC's
Flash
Code
DTC (PID
code)
Fault Description Possible Causes
17 B2291 (24) Passenger OPS Sensor 4 (outer
headliner/B pillar) - Sensor Fault
Connector: RF018, RF002,
SP028, SP030. Passenger
OPS Sensor 4. Harness: Roof,
Seat
17 B2291 (25) Passenger OPS Sensor 3 (A pillar) -
Sensor Fault
Connector: CR105, SP028,
SP030. Passenger OPS
Sensor 3. Harness: Cabin,
Seat
17 B2291 (26) Passenger OPS Sensor 2 (instrument
panel console) - Sensor Fault
Connector: CL006/007,
CL003, CC002, TL093,
SP028, SP030. Passenger
OPS Sensor 2 Harness:
Console Link, Instrument
Console, Telematics, Seat
17 B2291 (27) Passenger OPS Sensor 1 (center
headliner) - Sensor Fault
Connector: RF016, RF002,
SP028, SP030. Passenger
OPS Sensor 1. Harness: Roof,
Seat
17 B2291 (28) Passenger OPS Calibration Fault Clear Fault Code and Cycle
Ignition
17 B2291 (29) Passenger OPS Communications Fault Clear Fault Code and Cycle
Ignition

 

Bob,

Backup a minute........
You said you have cleared the RCM and are down to DTC B2291 with Flash Code 17 as the only remaining fault. At that point, you need to forget about the Occupancy Classification System, that is not what the fault is concerning. You need to pay attention to the Occupant POSITION System for now.

As far as the "24", that is not a PID. A PID is a 'Parameter IDentifier', that would be a parameter that a module monitors. In my example before I chose 24 only because you had mentioned that being read by your AutoEnginuity. That could also have been 25, 26, 27, 28, 29 etc. The bulletin I posted tries to clarify what the codes mean to help zero in on a failed component.

You say AutoEnginuity returns B2291-24; IF we assume that is actually the 3 byte DTC, then per the bulletin you need to start looking at the sonic sensor in the roof near the "B" pillar. [Here is where it might be nice to see if the Jaguar IDS would show the same code.]

Remember:
Flash Code 16 and DTC B2290 - Occupancy Classification [weight sensing]

Flash Code 17 and DTC B2291 - Occupant Position System [ultra-sonic sensors]

Don't over think it, go with what the system is telling you.

Good luck!

 

thanks for reeling me in Steve. I tried a replacement Occupant Position Module but only after clearing all DTC's with existing module still installed, then disconnecting battery, wait two minutes and installed the replacement module. Get the same results
I agree that it's best to follow the diagnostic info as reported by the AE tool. Even though the AE tools does not include the actual number 24 in it's diagnostic display, but rather their SW interprets the 3 byte DTC and displays the following "B2291 Occupant Position Sensor 4 Fault. Front Passenger".... which implies 24. And that is what bugs me. When writing application SW (code), it is entirely possible to erroneously map an enumerated data type such as a sequence of values 24 - 29 by mapping one of those value to an English string of characters such as "B2291 Occupant Position Sensor 4 Fault". SW isn't perfect but the Jag electronics system is one of the best in the industry. The AE engineer said that the Jaguar electronic systems starting around 2001 are very robust and I trust the vehicle is generating the correct faults.

When I asked AE how to confirm that indeed the fault is B2291 (24). they walked me through a procedure using their tool by first selecting Vehicle and then selecting "Switch System" which had a drop down menu showing all the potential systems. We tried "Driver Seat Module" and it was able to connect and gather all applicable sensor and other stuff. Then we tried "Passenger Seat Module" and the tool could not connect. So according to AE it was impossible to retrieve and display actual data stream since it could not connect to the module. They said you need to fix that first. Pinched wire, bad connection etc.

Back to the OPS topic...during the collision, a half full cup of Coke, splashed on the NAV panel on and around the Passenger OPS Sensor 2 - instrument panel console. I cleaned the mess a few months ago. Hind sight tells me, maybe I should have been a little more careful when cleaning up the mess. There is a chance, if I recall correctly, that I may have sprayed some windex right into that sensor...dam it. I like your idea of using an ultra-sonic vacuum leak or wind noise detector. Where could guy find one those?

I pull the B-Pillar sensor ( it has a very short lead) and I the two conductors are soldered to a tiny circuit board which fits into the bezel. it must be a transmitter and receiver in one.

In the material that u102768 posted ( thanks for that) the SRS System.pdf suggests the ultrasonic transducers operate at around 40 khz. Could I hang an oscilloscope probe on the sensor?

Bob

 

I doubt an oscilloscope on the sensor would be much help. I could be wrong, though.
I think the leak detector could be very helpful, I use it on these Airbag system sensors and also on the front and rear parking aid sensors in the bumpers, they work on the same principle. There are lots of the detectors out there, and they run the gamut on prices; here is one:

INFICON 711-202-G1 Whisper Ultrasonic Leak Detector | eBay

Good luck!

 

nifty device. Here is another...dig the KOSS headphones.
AIR WIND CABIN NOISE ULTRASONIC LEAK DETECTION | eBay

How do these ultrasonic transducers work? The OSM must have a 40khz signal generator in it's electronics, and maybe it sends a 40khz signal pulse of some known amplitude and length down one wire and the transducer emits that signal in the directon that the speaker grill is oriented and then the receiver portion of the transducer is more or less like a microphone and it's constantly listening for a echo of the 40khz signal coming back... and the OSM differentiates how long it took to the signal to bounce back. There must be a hard coded algorithm that computes the amount of time it takes for each sensor to "hear" the bounce of it's directional 40khz signal and providing it isn't Homer Simpson sitting in the passenger seat the algorithm can determine the location of the occupants noggin. But how often does each of the four tansducers emit the 40khz pulse? Sure seems likely that only one at a time is sending a signal so one doesn't interfere with the other... like maybe 100 ms interval between each sensor? that would allow the system to evaluate occupants position roughly 2 times a second by evaluating each of the four sensors two times every second. Maybe it needs to do it more frequently. The reason I'm going on with this is that I am curious how one of these leak detectors depicts or displays how often the pulse occurs. If each sensor generates a pulse ever half second for example, I think an LED or whatever it is that the tool uses to show the ultrasonic transmitter is working, would be easy to see with the human eye ( or human ear if the device converts the 40khz signal to something like 10khz). however, if the sampling rate is more like every 50 ms for each sensor, seems the leak detector might show you a constant indicator. So basically, the leak detector tells you if the sensor is generating click?

The only season I was thinking an O-scope might work is your can select a clock speed and amplitude on the settings and then probe one side of the sensor and then the other...
Thanks, Bob

 

Yes, they are nifty, I wouldn't spend THAT much for one though. A lesser unit works fine for this kind of work.

The sensors work much faster than once or twice a second. From the chatter I listen to, I'd say 15-20 times a second.....EACH. And they do it all at the same time. If you turn the gain up on the leak detector and just stick your detector in the car the chatter from all the sensors will drive you nuts. You have to turn the gain down so you can listen to each sensor individually.

You're an inquisitive guy, attached is some more information describing the system further.

Cheers,