wrightbenz

So first let me say I wasn’t aware my 97 SL500 had an engine immobilized. I have been doing some work, new car to me by the way and now the car just cranks kit start. I have one crappy key remote that will lot unlock the doors and is in bad condition. At any rate the car did start with this key. Now it is not I am not certain this is the issue but it may be based on the way the car sounds.
Is there a way to bypass the immobilizer ?
Will Mercedes sell me a new programmed key ?
What are my options ?
I also order a crank sensor as it has that kind of symptom as well.

optimusprime m1

This is hard to find if it wont start . The immobiliser will give the same problem as ht fault , so sorting this out is a job for the auto electric guy .I played for hours with the same problem replacing all the ht side with parts i had . Still i had no spark at the plugs all put down to immobiliser in the end,. Did you check for a spark,, if you have a spark i would say it would be fuel related .But the cps will,, and can stop the spark if faulty .Check crank position sensor with a meter . This will tell you if CPS is faulty or not You just pull it off , and check the ohms no need to have engine running to do this your only measuring the wire itself.

bobterry99

Instead of placing a bet on Parts Roulette I suggest that money would have been better used going toward the purchase of a Chinese-cloned Star Diagnosis System (SDS). Cost is about $300.

With SDS you could see whether or not your crankshaft sensor was working -- you wouldn't have to guess. And you could tell if the no-start condition was a consequence of an ignition fault or the "immobilizer".

Ahmed

Exactly my situation 100% right now.
I only have one OEM key FOB and it's in a bad state... MB do not make them anymore for my car.

I went ahead and bough a FOB case with key off ebay and had the key cut only as the PCB inside the OEM FOB couldn't migrate into the new case ( OEM has a transmitter laser part which my ebay case didn't have )

Anyways, the cut key unlocks the door, but won't crank the engine! Grrrrrr

FATHERTIME

You put the PCB and chip from the old case into the new one.

Ahmed

I tried, but the new case did not have a red window for the transmitter.
So I ordered another one and waiting for it to arrive.

Yes, it is easy to migrate the PCB and everything else into a new case. No big deal.

This is the correct one for my car with the red RF lens


This was the wrong one I ordered earlier.

optimusprime m1

And did it work ?

FATHERTIME

They really don't need the window but it's nice to see if your batteries are good. At least one of mine is a no window model.

Paul McCartney

Prior to '97 US models, W140 and R129 did not have a chip in the key. Immobilizer worked off the IR transmitter (the green board in the key). 97 is the only year with one button IR key, which had a micro chip in it. Chip must be programmed to immobilizer otherwise the vehicle will not start. There is a code which may be programmed to the chip, that any vehicle will write that key to it self, with a very small exception. When vehicle has an issue turning on headlights, wipers ets. - those could be related to the immo box, which has a chip operating the security system as well as controlling those convenience features. Whenever locksmiths pull the chip out - it is very hard to put it back properly, which can result in intermittent issues, such as described here. So looking at history of the vehicle, usually is the first step. Making a key which starts '97 is easy, but remote part is hard. Currently, there is no technology which can permit a use of a brand new key, the only option is to re-program a used key to your vehicle. From 1998 and up - all flip keys are available on the secondary market (not the dealer). Takes about 15 min to duplicate electronics of the existing key or create new electronic key with start/lock/unlock/trunk functions

Ahmed

Eventually, I had to cough it up!

Paul McCartney

God catch, but how are you going to program it? Would you like to sell it?

Ahmed

From the dealer, couldn't get it anywhere else.
It came from factory programmed.