Whats an Immobilizer??

i think the immobilizer is tied into the security system....

Hi Dave,

The immobilizer does what it says: It immobilizes the engine when the security system is set. I checked mine ('97 850) by opening the driver's window then locking the door with the key to set security. (Red LED flashing on the dash.) When I reached in through the open window and turned the key in the ignition, guess what......as in your case, "nothing happened".

Good Luck with the fix. (Wish I had my trusty '93 240 wagon back. No complex immobilizer! Who'd want to steal a 240 wagon?!!)

Andy I. ('58 445 "Duett" wagon; '65 122S wagon; '67 121 direct import

Wouldn't that defeat the purpose of an immobilizer?

Someone schrieb:

According to my manual ('00 V40) Immobilizer, Airbag, DSA and instrument cluster (fuse #11). But I guess, pulling the fuse will activate the immobilizer immediatly.

Roland

I have not checked, but my guess is that pulling the fuse would default it the wrong way....won't start. Doesn't that sound correct? ...Dave

Try it and let us know. Depending how "smart" those engineers are... I'm willing to bet that pulling the fuse will kill the immobilizer.

My point was trying to isolate the problem. Since you don't know which one it is between the two. I'm not sure if you can drive the car without intrument cluster...

Btw, I pulled the fuse >I have not checked, but my guess is that pulling the fuse would default it

Andy wrote: (...)

(...)

I've always wondered what that base model 121 was like. Would you mind describing the trim and interior, and how well the single carb engine pulled?

I would be absolutely stunned if pulling the fuse allowed the car to start. I've seen some bad engineering, but there's no way something that moronic would end up in a Volvo. Pulling the fuse will disable the immobilizer, and the car.

Actually, I'm more concerned about the instrument cluster. I have difficulty imagining being able to start the car without it. The ABS is a non-issue, and so is the DSA (Dynamic Stability Assistance). So it only leaves the immobilizer and the instrument cluster.

From a logical point of view, disabling the immobilizer should shut it down. It all depends how they programmed it in the computer. Normally, if a protection system is dead, it doesn't perform it's function.

Aga>

I don't know where you get your logic... The immobilizer is more like the ignition system or fuel injection system, in fact I would guess it's integrated pretty tightly into that. Engine management doesn't receive a signal from the immobilizer system, it won't let the engine start. Like I said, if it can be defeated by removing the fuse, then it is completely useless for the design purpose. It would be like a big lock on your front door held in by just one exposed thumbscrew. If it were the case, every thief would know about it and there would be publicity very quickly. Somebody go ahead and try so this stupid thread can end.

Many cars can be started with the instrument panel fuse removed, I wouldn't advise driving around like that but unless it's on the same fuse as the engine management stuff, the car will run just the same.

Hi "mjc13",

Sorry to say the single carb set-up had already been replaced by a twin-SU system when I acquired the car so I can't comment on the original performance. The trim was the same as our '95 122S wagon. It had front disc brakes but I seem to remember no servo booster! However it handled well, cornering as if on rails (or so it appeared at the time......) Exciting too, with a Kilometre per hour speedo, roaring through the city at 50! (Km/h........) Fortunately, Canada was just about to change to Metric about that time. Others were chasing around for stickers to adapt their speedos to Metric. Of course their odometers continued to register miles

Thanks for your interest. Andy I.

"mjc13 @verizon.net>"

I interpreted the immobilizer to be a third party system. Not a renamed ignition system or renamed fuel injection system.

I remember help>

I'm guessing you mean "'65 122S wagon"! Interesting that the trim was the same - I had read that they had no bumperettes and much less chrome. Maybe by that time they had to add that stuff to keep selling them...

"mjc13 @verizon.net>"

I have to agree with James, re. the logic of the immobiliser. The purpose of which is to stop any unauthorised person starting the car, my poor '87 740 has two third party ones fitted (don't ask; it just ended up that way), one (a single circuit one) is part of the remote alarm, which also handles remote central locking (very cool!) - this is manufactured by serpi star. The other system (a two circuit one, every wire is black) is just an ex BMW, laser line 'contact fob' immobiliser. I fitted both of these systems (Yes I know! Just who is going to want to steal it? LOL), and know full well that disconnecting power to either system will cause a no crank, and/or no fire situation. A manufacturer installed and specified to modernish standards system, such as fords PATS would be very tightly integrated into the cars electrics, they are also usually very difficult to find in the car, especially the bits that really matter, and the wiring is usually coloured and designed to be as obscure as possible. It would be really dumb if such a system could be disabled by removing a fuse.

Best wishes, Ken Phillips

Yes but it would help narrow down and id the fault, rather than spend $500 on the wrong "fix" then $500 on the right one.