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All of the X300s have the same accessory harnesses, so each car has many unused wire connectors lying around. Different markets have different options and requirements. Not to worry.
I can't identify the connector yet, but the wire colors don't match up with either the Catalyst Switching Module (Japan market only I think) or the airbag safing connector.
Only a week ago in the XJ12 section, on the most current topic (Power Steering Pump), John Baker found an unused connector at the rear of his engine (V12). I wasn't familiar with the connector and couldn't find it on my car. But the wiring diagram showed it was for thermocouples used in the Japanese market exhaust temperature warning indicator (along with the CSM). There is also a unused connector near the right A-pillar for the CSM.
Skips, It's not too late to edit your title to read UNplugged wiring harness! Usually you have 24 hours from posting time.
Don't be afraid to refer to your "maroon" XJ6 as your Carnival Red XJ6, it's proper color name. Not to be confused with the 1995 model year Flamenco Red! I had one of each.
Just before I logged in today I searched my computer's files for the "Airbags for Dummies" book by @Brendan. I thought I had it, but couldn't find it! So thank you Parker for re-posting it just when I wanted to use it. I'm going to troubleshoot my car's airbag system. It has been a low priority issue for a while now, but I have more time on my hands lately and want to get to the issue. Hopefully the control module is ok!
While you are in behind your glovebox, have a check of the airbag connectors (after disconnecting the battery and waiting 15 minutes or so). Unusually / uniquely these connectors have a "shorting bar" , which you can see embedded in the connector if you look at it end on, the purpose of which is to light your airbag light in the event that the connector should become disconnected, A very simple fail safe, which has the effect of connecting two of the wires together, and only breaking the connection by the action of the connector being inserted fully into the airbag module. The wrinkle is that with the passage of time, the stress of the bend in the wiring loom pulling on the connector at an angle causes just enough enough movement in the connector to allow the shorting bar to illuminate the airbag light. Ask me how I know this........!
Unusually / uniquely these connectors have a "shorting bar" , which you can see embedded in the connector if you look at it end on, the purpose of which is to light your airbag light in the event that the connector should become disconnected,
That's not quite correct. There is a shorting bar in the connection, but it is on the Air Bag connector side, not the loom side. It's purpose is to short out the Air Bag pins so that it cannot be deployed accidentally.
The Air Bag module constantly monitors the resistance of the circuit through the Air Bag. The Air Bag light will be illuminated if that resistance is outside the range 0.7 - 4.0 ohms. So if the Air bag is disconnected you will have open circuit and that's what triggers the air bag light.
That connector belongs to the ECU/fuel injection harness. LNA3340KA/B. This one is for sale on flea-bay right now. See the white connector on the left?
I found 3 loose resistors in the tool box. I tested them and found one to be a 2.5 ohm! Then I had to look up the color coding, and fell into the rabbit hole of resistor science for a while. I'm feeling educated about the airbag diagnostic testing now, not so much a dummy anymore. Thanks Brendan, that manual is brilliant! I'm suspecting the clock spring as the culprit. We will see...
Last edited by SleekJag12; 05-30-2020 at 05:03 AM.
Reason: Fixed part #
Please be assured, the shorting bar is most definitely in the multipin connector attached to the loom. Please also be assured, it shorts ground to the wire to the instrument panel warning light.
Were it not so difficult to access, I would take a picture. Were the shorting bar part of the module, as you suggest, it could not serve any purpose since the disconnection of the connector removes power from the module, and isolates it from other key components of the system. The purpose of the shorting bar is to ensure that the driver is aware that power has been removed from the airbag module, and hence the system cannot perform any of its diagnostics and checks, nor deploy in the event of an accident. It is a fairly simple and indeed quite elegant failsafe protection, and were it not in the loom side, it could not serve this purpose.
My car is 1995MY. Please be assured it functions exactly as I described in my previous post. Please also be assured the shorting bar on my car has nothing whatsoever to do with the Air Bag warning light.
Sounds like your car is different. I’m surprised, as I wasn’t aware of any variations across the model years for the Air Bag system and Jaguar only has one part number for each of the Driver and Passenger Air Bag modules for all years. But everyday’s a school day as they say.
Here are some pictures of my Air Bag connectors.
This picture is a drivers Air Bag unit with the inset clearly showing the shorting bar on the Air Bag module connector.
The Driver and Passenger connectors are the same but colours are reveresed.
And here is a picture of my multimeter measuring the resistance across the terminals on the unplugged Air Bag loom connector. Clearly not shorted out.
In tinkering with airbags , a meter can blow the squib , and that's bad
We would have to test the igniter squibs on engine fire bottles and such every so many flight hours
We used a given voltage battery with a given wattage light bulb as a continuity test light though the igniter squib without a high enough current to blow the squib
The squibs could only be shipped by land with a safety resistor across the squib connector
Not to take sides, but my car's airbag connectors look just like Brendans! Although I can see the value of a shorting bar on the loom side to advise of tampering or faults. This evening I tested my driver's side loom connector with the airbag simulator (2.5 Ohm resistor) and after re-connecting the battery, found the AIABAG warning still coming up. That's as far as I went today.
I worked at an airbag factory and learned that a shunt across the live pins of the squib pretty much guaranteed that it woudn't detonate. Big automated machines arc-welded the wires onto the small live initiator pins by laying a steel shunt across them. Only when there was an occasional malfunction with the position of the part or the wire, then BAM! That happened quite often with the production of hundreds of units per hour. In later Jaguar years, I was happy to see that finished airbags have an automatically shunting connector.
I'm still figuring out what that connector is from post #1...
The production of the 2 versions and the markets the cars went to is too complex of a concept for me to effectively deal with
I have yet to test the airbag system on M'Lady P since replacing the 2 airbags from the previous owners accident . In rewiring the car in its repair is where the owner got lost and the car didn't function properly
Luckely this forums members and resources will bring her to grace the roads again
We seem to be at crossed purposes.
If you go back to my original post, you will see that I am referring to the connectors to the airbag module, which is located behind the glovebox. The photographs you have posted are clearly of the airbags themselves, not the control module.
The control module has two multipin connectors, with shorting bars. The odd Y shaped prongs amongst the pins hold the shorting bars in the open, or unshorted position for as long as the connectors are fully engaged in the module. Due to the curvature of the loom as it attaches to the module , with the passage of time the prongs had bent slightly, enough to allow the shorting bar to short while the connectors were still fully engaged in the socket, hence illuminating the warning light.
Your original post referred to the Air Bag Module which is the correct term for the Air Bag itself, hence the confusion. The control module is correctly called the Air Bag Diagnostic Module.
But we all use many of the terms interchangeably (including me).
Me too Brendan.
It was quite the most bizarre fault I had encountered for many years, and my MoT was looming, so the light being on was a particular worry. I was sufficiently desperate that I took it in to the main dealer, who invested 3 hours trying to track down the problem, only to admit defeat and recommend replacing all of the airbag system........ The subsequent weekend spent working my way through it all is still etched into my memory, as is the relief at finding the problem!
Kind regards
Not to take sides, but my car's Diagnostic Module looks just like Countyjag's! I agree, it is behind the glove box and it does have multipin connectors, as he wrote earlier. I just learned it also has shorting bars inside the connectors. Another layer of safety! I saw the DM tonight as I was testing the passenger airbag loom (without change) and I managed to pull the plugs on it and reseat them. Still no change.
Parker - you beat me to the mystery connector ID. Nice work! Canister close valve and fuel tank pressure sensor. I see it is called PI 161 and the wire colors and positions match the schematic. Anyways, it is apparent that it is only used on two-canister systems. I was under my car to change the diff oil a couple weeks ago and saw there was only one canister. I had assumed there were two, but never actually looked for them! I'm certain that my old XJ6 had two canisters.
So there is your answer, @Skipstheboss. We must seem like lunatics. We're not. Ok, maybe there's just a little lunacy here.
05-28-2020, 08:03 PM
Although I can see the value of a shorting bar on the loom side to advise of tampering or faults. This evening I tested my driver's side loom connector with the airbag simulator (2.5 Ohm resistor) and after re-connecting the battery, found the AIABAG warning still coming up. That's as far as I went today.
I agree, it is behind the glove box and it does have multipin connectors, as he wrote earlier. I just learned it also has shorting bars inside the connectors. Another layer of safety! I saw the DM tonight as I was testing the passenger airbag loom (without change) and I managed to pull the plugs on it and reseat them. Still no change.