I haven't seen much on the forum about diagnosing Air Bag issues with early cars. I think some of the later models have a flash code diagnostic but the early ones have nothing, other than old Jaguar Dealer systems which I think are now rare. I have a VCM/IDS set-up and even that can't read the Air Bag module on my 1995 Daimler Six.

So I have used the various information available in JTIS etc. and produced an Air Bag Diagnostics for Dummies document (attached). It is specifically for early cars but I don't think there is much difference (if any) with later models.

If anyone spots any errors or inconsistencies then I'll be happy to amend appropriately.

I hope it will be of some use to someone in the future. Perhaps it can go in the stickies if deemed worthwhile.

 

Great write up - many thanks.
Do you have any more like this? :-)

 

Not yet, but I'm making a set of scope waveform pictures for all the sensors that I'll publish when I have enough to be worthwhile.

 

Terrific write-up Brendan. Thanks! I appreciate the effort it takes to create something like this.

Just what I needed for VDP. Tonight I got as far as checking the fuses! All ok there. My prediction is clockspring fail. We shall see.

This should definitely be included in the quick links sticky.

 

Superb, thank you so much for taking the time to complie and also for sharing.

Added to the How to / FAQ's

Thanks

 

Brendan,

Very well researched and superbly presented.

Thanks,
Graham

 

I agree Brendan! Super write up! I have an airbag light/message that comes on immediately when I turn the ignition on and it stays on, does not blink at all. Will start with your step by step testing, starting with getting the 2.5 ohm resistor!

 

2.5 ohm resistor a must

If you need a airbag to be shipped there are shipping restrictions as they are squib explosives

I did find someone in California that would ship for the right bag

And I got my other left airbag from a local salvage yard ( Jaguar model specific that I can tell )

 

Thanks Parker7. I am thinking about disconnecting both airbags (as they are over 10 years old anyway) and just installing the 2.5 ohm resistors in their place. then I can diagnose the rest of the system without worries they will deploy

 

Without me fully digesting Brendan excellent document

The resistors are for testing purposes to not have the test meter have too much current going through the squibs in the airbags themselves from blowing up the charge

The same value may or may not be good for your proposal on the module side of the connector , but as long as the connectors to the airbags are removed they will be safe

Caution must be observed when putting back together that there is not a voltage being delivered to the airbags as a replacement module may be in a firing state

The steering column airbag must match the interior color of the car as it comes as a whole unit with the exterior car horn pad , the interior color code is on the cars data plate

I have the part # for the passenger side and probably the steering side in the garage

 

Yes that's true. But what I need to check first is if all fuses to the airbag module are intact as my SRS light comes on as soon as ignition is turned on, doesn't go out and back on at all and the "Airbag" message on the dash comes on immediately also and stays on. AND, I don't have any communication with my airbag module with my scan tool. I didn't on my ABS module either but I fixed that by resoldering the positive/negative points where the connector goes and now I can read that module again!

 

Not all scan tools can read everything

lucky to get one to read transmission codes

see page 21

X300 1996 LWB.pdf (jagrepair.com)

 

I may just have found how to wire in my front and rear marker lamps/tail lamps.............. I made an extra wire at the power feed to the pilot lamp, left side, which is connected to the marker lamps and tail lamps which all are inoperable right now.... I plan to put that extra wire right at fuse #5 on the left hand forward fusebox as that is the feed for the marker lamps..... will see if I can get the lights to come on with the switch then...... if so BINGO i've solved my lamp problem!!!

I didn't have the fuse location and descriptions as my owner manual is missing!! THANKS!!!!

 

well so much for that as the #5 fuse has constant power not switched from the lamp switch so the saga continues.......

 

AFAIK there are no scan tools that talk to the Air Bag Control Module. Not even Jaguar IDS.

Maybe @motorcarman can confirm what they used at the dealers back in the day.

 

My airbag module was completed fried.(smell horrible)Have anyone experienced it? Not sure what caused it but I have the airbag light on before that. If I buy a module off eBay and reinstall it, is there a risk that it will burn again? Thanks!

 

Wow that is really smoked! That shouldn't happen. The white part at the top is the thermal fuse that blows above a certain temperature (which I don't know), saving everything from frying due to a short circuit somewhere.

So you both will need to do some checking of the sensors and such before you try a new module. This can be done based on Air Bags for Dummies, with a multimeter at the module wire plugs. Heed the warnings! Disconnect the airbags and put 2.5 ohm resistors across the sockets.

In my case the module looked fine although the thermal fuse was blown (open circuit). All other tests I did came up fine, so I put a new module in and all was well.

The Ford module from the same era is used in the Jaguar. It is easier to find. Recommend a new, not used unit. Match the numbers.

5 beeps Airbag warning

 

The 2.5 ohm resistors you speak of. What is the wattage on those? I see a bunch of resistors on Ebay but none of them 2.5 Ohms. I see 2.5 Mohms and 2kohms but not 2.5 ohms. please let me know which ones I need

 

Sleekjag12

Does this look like the right type ?? I don't see the same color bands as on the one in your write-up

https://www.tti.com/content/ttiinc/e...10&customerId=

 

You should not go under the 2.5 recommended , this increases the risk of bag firing off

I do have a good vender in town that has things "on the rack " as well as in stock in the back of the showroom

If you can wait I can mail you what you need

Researching