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Discussion starter · #23 · (Edited)
After researching and doing some long thinking, I think there is a problem with the EIS and it will get worse with time. Looks like the internet calls my problem a "no cold start" problem. It generally happens only on the first time its started for the day, (if it happens) and problem dissappears when the car has run.

I see that there are companies that specialize in repairing the circuit board (not reprogramming a new EIS). I have a strong suspicion they simply resolder some joints on the board or are just replacing old electrolytic capacitors.

How does the EIS know which position the user has turned the key into? I strongly believe that there are no physical contact points inside the EIS. There is probably another photogate inside it that tells the microcontroller in the EIS what position the key is in. For whetever reason this photogate is not working properly. A similar circuit can be found in the shifter, I was able to successfuly repair that. In my case there was a crack in the solder of a photogate. Because of this the computer in the shifter doesnt know which position the shifter is in and it wont change gear. The crack was caused by a piece of moving plastic (called a curtain) whose corner tends to catch into the photogate. The fix was really easy: Resolder the joint, round the corner of the plastic curtain so it doesnt catch again.

Here is a link to MBWorld with a similar EIS having a simiar issue. No Start/Intermittent Start Problem - MBWorld.org Forums


@Avel Du if you have the work instructions for removing the EIS. I would appreciate it. I intend to remove mine this weekend and see if the problem is similar to the shifter.
I really dont want to get stuck in the middle of nowhere and hire a tow truck which costs hundreds of dollars. Worse case, if the EIS is really bad, it wont unock the steering column, you might not be able to load the car to the truck!
 
For remove install of EIS see attachment.
Added some more info just in case. There is no function description document for pre-FL EIS only for FL EIS. Same goes for wiring diagram. But I think it is the same for FL and pre-FL.
All I could find. There is no documentation on how these things exactly work.At least not that I could find.
 

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Discussion starter · #26 ·
@Sneaky Pete thanks for the info.
unscrewing the EIS seems to be an easy thing. But to get it physically out needs the removal of the “cover below the instrument panel”. AR68.10-P1500V is this another work instruction? Or is this a part number? there is no detail on how to remove this panel. Help please. Its better to know where the latches are else we snap off old brittle plastic again. :) thanks in advance.

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Discussion starter · #29 ·
so this week I experienced the no start situation twice. The problem seems to be getting worse. I am convinced there is either a cold solder or poor contact in the EIS. Based on the docs given, the EIS seems to be something easy to remove. Ill wait a month more then open it up. I will have more time then. I’ll update you guys.
 
Discussion starter · #31 ·
Ok. Problem is getting really bad. This time it’s happening every morning. I am going to open the EIS and inspect.
 
Discussion starter · #32 ·
EIS removed. Now I need some help from the experts. I see 2 switches located on the board. I believe these switches tell the circuit the key is in either position 1, 2 or 3. i know there should be more perhaps some are inside the key tumbler itself. First question is what does switch number 1 do? (I just labeled it switch 1 for discussion sake).

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the copper levers actuate it but i am not sure when because I cannot turn the key without powering up the system. please someone tell me at which position does this one get actuated. I suspect this is at either position 1 or 2.

then there is switch 2. Located here:
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there is a small gap between the plunger that presses this switch and the actual switch. Not sure if this is normal or has widened due to wear.
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Someone please tell me when this switch is actuated. I suspect this switch is intermittent. I suspect this switch is actuated at position 3 (actual start).
both switches are not easy to replace without removing the key mechanism which looks like a lot of careful desoldering work. Unfortunately as well, I have never had any luck cleaning these kinds of switches with contact cleaner. I usually just replace them when they go intermittent.
for now I will insert a small plastic sheet in between the gap. Hopefully it will be enough to convince that switch to switch more reliably, if that is indeed the problem. I am absolutely convinced that the problem is with a contact switch. it is not a cold solder. It may or may no be this particular switch but it is definitely a switch. I hope everyone will benefit to know which one.
@Avel Du @Sneaky Pete help.
 
Discussion starter · #34 ·
I’m no expert, but Pete is solid.

I will add @Dave2302
ok just to update you all. Switch 1 is actuated when you insert the key, so still in position 0. Switch 2 is actuated when you turn the key to position 1. These two switches have nothing to do with the starting (position 3). So whatever the problem is, its inside the key tumbler. I know in the end the problem will just be some dirty or slightly corroded contacts, but to get into that tumbler is the challenge.
For me I am very sure the problem is the contact on position 3 because the EIS doesnt raise any errors. If there was an error state, i.e. switch 2 is activated but switch 1 was not, the system will surely raise an error of sorts.
I also found out if I switch to position 3 really slowly, the car will start more reliably.
 
What @efair says. How the EIS internals work is not made available by MB. There is no documentation available (not public and no workshop) by MB. Possibly only in the MB development department. So only way to find out is by reverse engineering as you are doing. So yes, if possible document as much as possible. May help a lot of members.
 
What EXACTLY is your problem?

I have something .. similar.. I insert key, turn it all the way to start (pos 3), nothing! Take the key out, turn it to ignition (pos 2), wait a few seconds (until dash lights up and needles etc starts moving), THEN to start and it starts right up.

Often, that wait in pos 2, the whole cluster is completely dead. It can take as long as three, four seconds.. But if I wait, it will light up. I don't have to jiggle the key or anything. There's just a delay.


This LOOKS like what the video you linked to have as well. He just didn't seem to do the wait. AND, if you look closer, when he "fixed" it, he doesn't put the key in and turn to start right away, he waits at ignition! THEN starts it.. Just what I have to do..

MY problem, I seriously doubt it have anything to do with the ignition switch! Not impossible, but improbable. IMO..
 
All I can do is ask dumb questions…

I wonder if it uses a hall sensor for detecting the key rotation like the camshafts…. Or capacitors like the front SAM… Or if it’s wave soldered like the K40’s of the R170.

You must be careful since breaking it means a tow-in to a really good shop or the dealership.

How many connections are there between the barrel and the circuit board?

And it looks like there is a heck of a relay on it, have you tried measuring the load side during cranking to see if it’s wonky?

Which external pins, if any, do the load and control circuits of that relay connect to?
 
Discussion starter · #39 ·
All I can do is ask dumb questions…

I wonder if it uses a hall sensor for detecting the key rotation like the camshafts…. Or capacitors like the front SAM… Or if it’s wave soldered like the K40’s of the R170.

You must be careful since breaking it means a tow-in to a really good shop or the dealership.

How many connections are there between the barrel and the circuit board?

And it looks like there is a heck of a relay on it, have you tried measuring the load side during cranking to see if it’s wonky?

Which external pins, if any, do the load and control circuits of that relay connect to?

I wonder if it uses a hall sensor for detecting the key rotation like the camshafts…. Or capacitors like the front SAM… Or if it’s wave soldered like the K40’s of the R170.
- I think it uses a mechanical old fashioned electrical contact switch. I know it could have used some non contact alternative like an optical gate or hall sensor which will make the switch last a lifetime but it doesnt seem so. We will know for sure when I open the tumbler/barrel.

How many connections are there between the barrel and the circuit board?
- 6 connection points. One of them is to VCC (12V). 3 of them pretty much go directly to the output connector, the big one with thicker wires. For now I do not know why they made it this way, it seems that the contacts in the barrel will be conducting more current and probably going to throw a bigger relay outside the EIS.

And it looks like there is a heck of a relay on it, have you tried measuring the load side during cranking to see if it’s wonky?
I do not see any relays anywhere. The coil you might see is a solenoid that pulls a lever that allows you to turn the key, presumambly after the key and the EIS has exchanged data and drive authorisation is given.

I will give a more details as I discover them.
 
Discussion starter · #40 ·
What EXACTLY is your problem?

I have something .. similar.. I insert key, turn it all the way to start (pos 3), nothing! Take the key out, turn it to ignition (pos 2), wait a few seconds (until dash lights up and needles etc starts moving), THEN to start and it starts right up.

Often, that wait in pos 2, the whole cluster is completely dead. It can take as long as three, four seconds.. But if I wait, it will light up. I don't have to jiggle the key or anything. There's just a delay.


This LOOKS like what the video you linked to have as well. He just didn't seem to do the wait. AND, if you look closer, when he "fixed" it, he doesn't put the key in and turn to start right away, he waits at ignition! THEN starts it.. Just what I have to do..

MY problem, I seriously doubt it have anything to do with the ignition switch! Not impossible, but improbable. IMO..
Hey Turbo! My problem is that key can enter the EIS. It unlocks the ESL. Allows me to turn to position 1. Accesories light up as normal. Allows me to turn to position 2, futher accessories light up as normal. I turn to position 3 to start the car, NOTHING, as in the EIS didnt even know I turned it. No error codes. Then I try again until for one reason or another, the car starts as normal. Battery is not an issue. Usually once it has started, a second try will be reliable. Until the next day. Tapping or shimmying the key does not help. Turning the key to position 3 very slowly seems to make the starting more reliable.
 
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