1998 W140 S500 no start, "start error" displayed on odometer
 

Car in question is a 1998 S500 W140 USA version.

Up until it didn't, the car ran and started fine.

Went to start up the car last week, and the car cranked, then would fire for a second, then die. I could see the tach jump, as well as the oil pressure gage before the car died.

First thought was a bad key (rfid chip). Unfortunately, my wife cannot find the spare key she had while we were on vacation two weeks ago. (I always like to have a spare key with me when out of town.)

So, I make the trek down to the dealer for another key. Got the key from the dealer and it has the same symptoms as the original key. Note: The new dealer key does not remotely operate the locks. I swapped batteries, between the new key and original key (which were two months old) and no change. The original key still locks/unlocks, the new one does not. I know that the batteries in the key do not affect starting, but it makes me wonder about the veracity of the new key, as in, did I get a bad key from the dealer. Both keys do turn the tumbler and crank the engine.

I also traced the wire from the transponder ring (coil) to the black box above the steering column (part # 129 820 37 26, SIEMENS SWK4 680 PA6-GR30), and disconnected the transponder ring pigtail and checked the transponder for continuity, and it showed 0 ohms resistance.

Doing a data dump on the car with the XENTRY system, I get a code ME1R, "P1570 DAS to engine control module N3/10 faulty".

Testing for actual values, I get:

57 DAS and ECM compatible?

Yes

53 ECM identified?

Yes

54 ECM locked?

Yes

55 Start auth?

No (Ahah!)

56 Vehicle locked with DAS?

Yes

66 Number of starts with non-locked ECM?

Starts=0

Other info displayed:

Code# 032302064
Code unit# D7F650
Chassis # ---------375

And a reference to DAS control unit 82801.

So far I have not found the location of N3/10 or 82801, which might be the same module....


Anyone have any suggestions on what to do next?

Thanks for any thoughts!

Jim

Still sounds like a bad key. Wouldn't be the first time I've seen the dealer goof it. Although for giggles I'd disconnect anything else on the engine CAN bus like the ETC and ABS and see if you can get start authorization. Every once in a blue moon you can have another module on the CAN bus putting out enough noise that the authorization message cant get through.

The black box that the transponder ring plugs into is the DAS box. This takes the code from the key, if it matches the code in the box, it then sends a signal to the engine computer to turn on fuel. The DAS box also sends a new code to the key for the next start.

There is a white connector with 2 green wires that plugs into the DAS box , this is the CAN bus communication wire that lets it talk to the engine computer make sure that is plugged in.

To resync the remote locks, point the fob towards the IR receiver, press the button 2 x , insert the key in the ignition and turn it to run. The 2x press alerts the IR lock system that a new key is being set up and turning it to run verifies that it is a real key not a hack. I'm not sure if the DAS issue will prevent registering the key.

I'm pretty sure if you unplug all 3 plugs from the DAS box, the car will start stall rather than just not try to fire.

If you get parts as a test, you need a key / DAS box / engine computer all from the same car. Mix and match won't work.

I'd love to find the original spare key......

However my wife swears she put it in the key drawer. And those of you who are married, know that sometimes it's better not to pursue certain lines of questioning... even if you *know* the key never made it to the drawer.

Jim

Thanks, I'll give the key synch a try tomorrow.

I did remove and reset the three connectors to DAS box, with no change.

Fiddling with the XENTRY diagnostics, it seems to me that I have the ability to marry a new component to the car. Given the code and info in the OP, would the DAS box be the culprit in this case, assuming the new key is good?

Jim

Well, I tried to synch the new key as you outlined. No luck.

I did find one new DASmodule @ parts.com, I may go that route if I can verify that the XENTRY system will allow me to program the new module. Playing with the menus yesterday,it looked like the XENTRY system allows me mate the DAS with the ECU and key.

Also saw this thread:

http://www.peachparts.com/shopforum/tech-help/380518-w202-p1570-das-fault-solution.html

I'll check fuses tomorrow, it's raining right now..... But unlike the symptoms in the above thread, my door locks, etc. are working.

I wish I could have more confidence in the new key either being good or bad, hate to gamble over $800 if it's not the root cause.

Jim

BMW experience....
 

Another datum point, we also have a 99 BMW Z3.

Last year I had similar problem with that car. The rolling codes got out of synch and the car refused to start. The final fix was to send the ECU to a company that spoofed the ECU into seeing the OK-Dokey from the key/transponder/DAS making the key RFID chip irrelevant.

So far, I have not found a company that can do this for a MB.

Jim

If you dig around on e bay, there are chip readers that will make a key from the DAS box memory. However the DAS box must match the ECU.

Someone on e bay was also offering a service to unlock the ECU to allow it to be paired to another DAS box. ( After 40 or so starts the ECU locks out the ability to pair with another DAS box.

Jim,

Check to see if your chrome ring(the coil) on the ignition is not pinched or open from the connector on the DAS box behind the cluster. You pinch, or cut that wire, and you are TOAST....

The signal is not picked-up

Martin

As noted in the OP, I checked the transponder ring by unplugging it at the DAS module, and verifying continuity via an ohm check. The transponder ring showed 0 ohms resistance. That suggests it's good, right?

Jim

Well, it's gotten interesting.

We picked up a parts W140, one that we verified started and ran (not move, the tranny is bad).
Recall the good car is throwing a P1570 code, indicating a communication problem between the DAS and the ECM.
Swapped out the ECM, DAS and set up a loose transponder ring with the parts car RFID chip key next to it.

Still got the start error.

Now it gets interesting. We took the ECM, DAS and transponder coil and key from the "good" car and swapped them into the parts car. Guess what? The parts car started. Also worked fine with the new dealer key.
Seems like the next area to look at is wiring continuity.
The aftermarket clone SDS system I'm using has the wiring diagrams on it, but I have not been successful in finding them yet.
Think I need to sit in a chair, with an adult beverage and play with the system for a while......

Frustrated, but at least I don't need to drive the car tomorrow. Been driving the BMW Z3 in lieu of the S500, kinda getting used to it, it's a fun little go cart. Might be nice enough next week to consider putting the top down for the commute.



Jim

Since the remote locks don't work, I'm wondering if that module is pulling the CAN bus down. As our guy said in post 2 start unplugging the CAN wire on anything you can find.

When you use the metal key to lock / unlock the door, do the other doors automatically lock / unlock? ( I'd try this with the trunk and windows down in case something bad happens and locks you out. )

Given the trans computer on these cars tends to get wet with trans fluid from a bad transmission plug bushing, I'd have a look there. It might not be the actual source of the problem but it is good PM regardless.

That SDS system might not have wiring diagrams.

I've seen 2 CAN bus style on Mercedes so far. 1: Daisy chain, with an end of line resistor at the modules at each end. 2: Star, where all CAN wires connect to a common point, I'm not sure if each module uses an end of line resistor.

I think my cousin indicated in post #1 that the remote lock still works, and has always worked, with the original key. He indicated the replacement key from the dealer didn't work which might be caused by the new key not being synched to the car?

Since we can swap the DAS, engine ECM and transponder ring from the original car to the parts car and get them to work it seems like the problem would have to be a wiring, connector or power issue in the original car.

Does the DAS unit coordinate/originate the remote lock/unlock activity?

DAS might be a stand alone unit in those years. I _think_ only the ML has the DAS / locks linked.

Whenever the ATA (anti theft alarm) started to stay armed even when the key / remote was used on my SL, the remote locks became erratic and would no longer work / resync. I wonder if the anti theft system can shut the engine down if it thinks there is a break in even if a valid key is used. Might be worth unplugging the ATA and RCL.