E300 won't start (immobilizer kicks in) - Benzworld.org

jbirdfunk · 08-20-2006, 07:38 PM

Hi all,

Nice forum.. Hopefully someone has some tips for me.

I've got a '96 e300 I recently bought used that worked great until the other day. I attempted starting the car and it would not start but was turning over fine. I realized the rear view mirror green/red lights were flashing off and on. From what I can tell the immobilizer has kicked in for some unknown reason. The first time I was able to "reset" something by disconnecting the negative terminal to my battery and the car subsequently started normal, no immobilizer problems. Then a week later the same problem. Again, I disconnected the negative battery terminal and it worked... All of these times nothing abnormal was done after shutting off the car, locking it as normal either with the key at the door or the infrared remote. Also no obvious errors are reported in the dash that I see. Also using the infrared to lock/unlock the car still works fine but does not clear this error.

The car has sat for a week, I come home and try to start with the same problem. However, this time the battery trick is not working. I'm about ready to roll the car off a cliff.

Any tips of things to try or should I just take it to the dealer? I am correct in understanding the immobilizer has been engaged? The car seems to have been very well maintained otherwise..

Thanks,
-Jason

E-Klasse · 08-21-2006, 11:51 AM

Do you have the owners manual with the car? You may ned to resync the remote with the computer to clear the flashing lights on the rear view mirror. That happens if the battery is changed in the remote key fob. Other wise the security system is messed up so your fuel pump relay is not working. You can lock and unlock the doors with the remote? I would do the resync first to see if the light stop flashing after you replace the battery in the keyfob.

I have heard of problems with the 97 with the big ring extending out from the ignition switch. It is a coil that reads to chip in the key fob. If the keyfob is bad, it will not let you start the car.

jbirdfunk · 08-22-2006, 11:36 AM

Thanks for the reply. Yes the key fob remote locks and unlocks the car without problems. Does this mean I still need to re-sync?

I'll buy new batteries and see if that helps.

anmar75 · 08-27-2006, 04:52 AM

i am having almost the same problem apart from my door doesnt open manual for a physical reason

Ken Owen · 08-30-2006, 06:13 AM

I have an almost identical(but intermittant ) problem. Two tows and ten days at a MB dealership and I am non the wiser. They have replaced a unit that receives the fob signal and sends it to the computer (called an FZsomething)
I am hoping this will fix the problem.
computer was sent away for testing and came up OK. All electrical lines were checked.

I am very keen to hear about your progress
Regards
KO

anmar75 · 08-31-2006, 12:24 PM

thats what the AA man told me ...
the red light on the mirror if its stops working you will nead to change the mirror cost new £110 + VAT from MB i will explain the fitting when i do it in pictures

jbirdfunk · 09-08-2006, 11:35 PM

OK so I replaced the key fob batteries with new energizers. Seemed to work for a while but of course the problem came back.

One thing about this car is I rarely drive it.. and tonight I tried the car and it would start fine, but earlier today at 5pm or so it would not start even after repeated trying to resync the key.. It would lock/unlock the car fine with the remote..

From what I remember it FREQUENTLY has this problem around that time of day. Cars parked in my driveway point due west, right at the sun. Is it possible the optical eye on the visor is getting whacked out due to sun rays and hosing my ride? Am I crazy? I hate this problem and want to unload this car!

anmar75 · 09-09-2006, 05:02 AM

it happens to me as well when there is some sun in london .. as we have only rain all the year .. but my problem is i cant open the door manually coz the door lock is stuck some how ..

izuyan · 08-26-2007, 03:37 PM

I have exactly the same problem on my '96 E300D. A local mechanic tried to fix it by replacing the car's battery as well as the battery in the keyfob. It seemed to work for only a week or so, then the same problem came back.

I am now thinking of installing a retrofitting keyless entry system to bypass the factory alarm system.

Does anybody have experience?

Thanks.

**Matt L** · 08-26-2007, 04:58 PM

Check the K40 relay module. There are a number of threads on that piece.

Attempting to retrofit a keyless entry system will not solve this problem.