Recently purchased a used LR3 for cheap. Sorting out a bunch of gremlins and one of them is the pretensioners. SRS light that wont clear, and a "pretensioner, signal implausible" DTC
I have seen many posts and a tech bulletin about the wiring, so I assumed it was that. However, further inspection revealed they had gone off. No other evidence of any air bag deployment that I can see.

Is there a spot in the IID tool that will show me air bag history? I assumed those sorts of faults are hard-written to the ECU and cannot be cleared even if you replace any that have gone off.

I got two pretensioners out of an 07 RRS at the junk yard and can replace them easily, but I'm worried if there is some sort of short circuit in the wire harness, maybe they will just deploy again when I hook the battery back up?

Any advice on other things to check before I ruin a perfectly good pair of tensioners? All I can think of is looking for continuity on the harness connector with a multimeter.

*EDIT*: I probably should have stuck this in the Tech help section rather than the general LR3. Apologies

Some other possibly pertinent information: The car has suffered water ingress from sunroof drains (had to resolder joint for key-fob remote control, and there's some rust on a few fasteners at the base of the seat rails) and I think the car sat for upwards of 2 years undriven (15 year old tires I took off had water in the rear two, suggesting they had gone flat for a while?)

Thanks for any advice or insight you can provide

 

If you have a GAP tool have you not tired to just reset the SRS system?

 

Tried that before investigating. Since the tensioner are blown/went off, the code comes back immediately. I suppose if someone was off roading it and hit something at low speed, maybe that caused the belt tensioner to fire without the Airbags.

I'm just paranoid that its a damaged circuit that will fire again, but what are the odds both the driver and passenger has the same damaged wire or short?

I'm probably overthinking this. Air bag stuff just scares me a bit.

 

And you make sure they are plugged in? And to be clear, the pretensions are inboard, along the center console. If activated the belt buckle would be pulled deeper down between the console and seat making inserting a little difficult I believe. The accordion like arm that supports the buckle would be compressed. They can activate without the airbags going off, but I think that is only if the truck is rolled. I you replace them, obviously do so with power off but I am very certain the will not go off again. They are triggered by a signal from the restraint module, so for them to go off again the module would have to detect a roll over. There is a specific sensor for that and you dont mention any other codes. And if thee was a code for it, the system would be disabled anyway. I dont think any damage to wire would trigger them, certainly not both since they are not activated together normally.

Lemme see if I can find some tech info.

 

Check these out. Not sure if they will help much. I was looking for workshop manual on installing new pretensioners, but came up empty.

 

Also... maybe worth reading:

DISCO3.CO.UK - View topic - Discovery 3 - Airbag Warning Light

 

tTanks for the resources! Its funny how many revisions for workshop manuals there are out there. Ive got one thats 4800pages but differs slightly to the excerpts you linked.

So I'm probably safe to get the battery hooked up and not worry about the pretensioners just randomly going off. Seems like the system needs a signal that would be hard to replicate by a short in the harness.

Kicking myself for not grabbing the clock spring out of that range rover at the junk yard though. Seems like it can suffer wear and tear issues and this truck has 185k miles

 

For what it's worth, my LR3 driver's side pretensioner went off about 5 years ago when I was the middle car in a low speed collision during commuter traffic - someone bumped me at about 20 mph, pushing me into the car in front of me. Airbags didn't deploy, pretensioner did. Airbag SRS light did activate as a result, and triggered the pretensioner code. Crush cans were okay but the bumper cover, hood, and a headlight needed replacing. In the back I had a hitch on that day and the car behind me got stopped pretty much dead on it. My frame is apparently still straight, too. I bought a new pretensioner from the dealer whose parts department seemed pretty uncomfortable selling it to me despite happily selling me other parts, and swapped it myself. Airbag SRS light went away immediately without even resetting codes, as soon as the seat was plugged back in and the car started up. Anyways, no rollover required, apparently there is a level of G-Force from impact velocity that is enough to trigger pretensioner but not enough to trigger airbag, and I was in that range.