98 CLK 320 EIS / Key / Anti theft module ? - PeachParts Mercedes-Benz Forum

97 SL320 · #1 12-08-2012, 04:44 PM

I have a chance to buy a 98 CLK 320 that is currently not running.

The owner's ad claims the key needs reprogrammed or the EIS module changed. Anyone have experience with this system? Is this the "Smart Key" nub that plugs into the ignition switch rather than an actual metal key?

I'm always up for interesting tech heavy projects and if the owner comes to a reasonable asking price I may have a run at it. They were asking $ 5,700 , then 4,600 and now 3,000 OBO. _Running_ the cars don't seem to bring much over 4,000 and this car needs door rust repair , has a bent wheel, dented fender. I'm thinking more like $ 1,000 max unless someone on this list feels otherwise.

Thanks

Gilly · #2 12-08-2012, 08:31 PM

It is Smartkey (bladeless key w/EIS). Can be a can of worms, you can't shop for stuff at junkyards.
Key is never "in need of programming", you need to ask specifically what the car is or isn't doing, and if there are messages in the odometer when you try to start it, like an error message. Could be a bad key or EIS, you have to be really careful about this, could really bite you because a lot of this security-related stuff can only be done by the dealer, as well as ordering parts like keys and the EIS.

ps2cho · #3 12-09-2012, 12:06 AM

For what its worth, a new key at the dealer is $287 out the door. I got a quote for our 2002 CLK320 a few months ago.

As Gilly said, its not "reprogrammed".

I believe the early 320's had harmonic balancer issues so check to see if its done, other than that its a rock solid engine.

Gilly · #4 12-09-2012, 04:57 AM

Oh and in addition if the guy says the battery in the key needs to be replaced, that is false, there are replaceable batteries in the keys but they are only for the remote locking, not used for the starting of the car at all. The car will start just fine even with the batteries removed.

97 SL320 · #5 12-09-2012, 09:01 AM

Thanks,

I'll find out if the car has eror codes , cranks but won't fire or won't crank then research if the anti theft system drops the starter or fuel. The ad says they talked to "Mercedes people" ( Re internet ) and were told the key needs "reprogrammed" ( $ 350 ) or the EIS changed ( $ 900 ). I'd think if that was all that stood between a running car and scrap they would make it run again.

As a trade in the car has near zero value, for a Mercedes dealer it is too old to sell on their lot and a used car lot too afraid of it.

Gilly · #6 12-09-2012, 05:29 PM

I think it's crank but no injection but can double check if you want me to.Also could ask if the steering wheel unlocks if the key is inserted, that all is dependent on the key and eis to agree to do (done electrically when the key is inserted and authorized)

97 SL320 · #7 12-15-2012, 05:51 PM

I've doing some research on the EIS and came up with this tid bit on an aftermarket equipment site.

**********
Equipment

Functions: 1. Reading of number, ID and status of a SMART Key for Mercedes Benz.
2.Testing of function ability of a SMART Key – both of Radio Frequency and Infra Red functions.

##### !!!!!!
3. Checking of a limit of starts of a SMART Key.
###### !!!!!

4. Radio Frequency volume detection.

*******

Then I find a further explanation ( rolling code that never repeats apparently )

**********

As it is known, hash is mathematical 8 bytes or a word, a coded word. And the level of
coding depends on the number of hash functions calculations.
The hash functions feature is one side coding. Let us have an 8 byte word like initial hash or password.

###### Using this initial (first) hash, we can calculate second hash, then third hash, using second hash etc. up to 200 000 hashes. ####

But hash function has one important property. We are able to calculate it forward only, hash has not back calculation. Then we can not calculate first hash when we have second one ets. CPU inside the key has 200 000 hashes and send them hash by hash from 200 000-th hash to 1st hash to the EIS.

**********

So, It looks like the key has a limited life and requires uninterrupted key send / EIS receive. I see a scenario where one data miss read cause the key to advance to the next code while the EIS is still on the old code and the car not operate.

From what I gather, other remote rolling code systems, like a garage door opener, IR / RF remote locks, use a rolling code block. There exists a list of codes in the computer and remote. The remote sends a code, the computer looks at the next one on the list but will accept a code XX down the list. This is done to account for remote button presses when away from the car.

The IR remote on my 97 SL320 has a sync feature where you cycle the IR remote at the car then insert key in ignition and turn on to resysc. Apparently the Smart key does not have such a feature.

engatwork · #8 12-15-2012, 06:13 PM

Even if it has to go to the dealer for a new EIS and key you are only looking at around $750 IIRC.

Gilly · #9 12-15-2012, 08:10 PM

Well, that's a bunch to digest. I have all the info from MB regarding the smartkey. 200K starts I believe is correct. It would take a long time to reach that many starts. In class we sort of figured out that in normal use it would take probably more years than the car will last before the key was out of codes, unless it ends up in some museum.
If you start the car 10 times a day, every day of the year, that is a lifespan of almost 55 years before you run out of codes. And we figured 10 starts a day is at least average, probably above average (the 10 starts seems right but then figure that there are days or even weeks when a car is not used due to vacations, etc). Plus you have 2 or 3 keys with the car.
It is a "rolling code" if you want to consider it that way, to me not really in the common sense of rolling code though. It was described to the class as a "challenge and response" type of activity. To simplify, when you insert the key, the eis will challenge the smartkey for example "9 times 9" and the key will respond "81". It's no that the key calculates the response, it is already programmed to give that reply (the correct reply) on that start attempt.

97 SL320 · #10 12-17-2012, 02:19 PM

Update on the car. The owner says the key turns but car "won't turn on".

They bought the car from a friend for Mom to drive, had it towed ( apparently not running ) to Moms house and here is sits. Now they say that Mom can't afford to repair it.

The also claim that a salvage yard offered them $ 3,000 as it sits, I told them I'm going to pass as running cars can be gotten for slightly more than that.

I get the sense they know nothing about cars and it is way worse than they are aware of.

Gilly · #11 12-17-2012, 04:44 PM

Would take a bit of diagnosing if what they say is true. If the key turns, that means the EIS and key are fine, and there is at least some minimum of battery power, or else the key would never turn. To take it to the next step, "the car won't turn on", it's like whoa, the EIS is authorizing the key to turn, but the car is otherwise essentially dead??? WTH???

SatRoc · #12 07-21-2016, 09:14 PM

Had the same problem with a '99 CLK320. Bought all the items required to fire up the car for, if I remember correctly, $450. This included new used EIS, Smartkey, the unit that locks the steering wheel and ECU. Plugged it all together and fired up the car. After a year, all's well.