[alexus.one]

hey all got kinda wired problem with my C280
lately it started to stall on the road usually on traffic light thei had few stalls in higwat... lights go off engine goes off, after few min i can restart... seamed like position sensor, was replaced but did not help.

how i have more distinct symptoms. i start the car all good, press brake to shift to drive car dies, lights go off (speedo lights). If i try to restart, seat belt tight comes on but going to ignition position no other lighs are cumming on at all. Moving to next position no cranking. Then i wait a bit try again diagnostic lights blink and die at once. Then some time after i can start and die on pressing brake and finally in about 10 in i can start and drive just fine for whole day. Note car is cold so deffiently not a position sensor.

Star diagnostic shows no codes. What can it be? ECU? Keylock module was replaced about 5 years ago with new one so probably not a case.

Any ideas?

 

[Patman1]

K40

 

[alexus.one]

tnx, reading symptoms of K40
some people say their roof and other electronics goes off in case of K40 in my case roof, doors, in-car lights are working. Do you still think its K40?

 

[Patman1]

Yes, K40 protects loads of electronics from damage. It's the #1 cause of haywire electronics on 90's MBs. Luckily it's really cheap, even if bought brand new.

What really is drawing my attention here is the fact the lights go off on the dash. If the engine died for any other reason, the cluster would go back into the bulb-test, so all the lights would be on.

 

[alexus.one]

played around today, if i disconnect K40 block there i no crank but diagnostic lights are on so its not K40, i event took of ECU and partially diagnostic light are on like ABS, ESP. Where when i can not get cranking i see no lights at all. Playing around i started to suspect that issue with ignition swith actual electrical power part but i dont know how to diagnose it, maybe if i take whole thing apart and make bypass harness i can connect wires directly without switch and see if i can get situation where is no cranking, if u try say 100 times and no issue then its a switch.... does not seam to reliable test as im getting issue show up like 5 times dyreing my today's test (that's in 3 hours) + i think getting ignition switch out is not easy

 

[Patman1]

It might be the ignition switch. I've heard of an issue with some of the first electronic ignition switches, but I thought that issue was only confined to W140 cars. I'd suggest you try searching that forum for information, you might find some people with similar symptoms and read up on their solutions. From what I remember, the issue was caused by the same fault that plagued the first K40s and the older OVP relays, poor soldering quality which eventually cracked and caused intermittent issues.

 

[alexus.one]

well i checked K40 soldering looks perfect to me, even overheat on clear coat. I already ordered switch part, will need to figure out how to get it whole assembly and replace it. I cant even find removal tutorials. Searched whole net and all post are about different things that are much easier to pin point. I usually can figure out any problems on the fly but this one drives me nuts. If it ends up switch then it will be so bad engineering not to have a fail over procedure for this. Like even MB window buttons are doubled so if one contact fails there still another (although there is no diagnostic on those) I'm being jet pilot kinda used to guaranteed fail over on critical parts like engines lol

 

[Patman1]

Well I'd be careful with that assumption, the cracks in the solder are microscopic, they wouldn't show up to the naked eye.

 

[Jostep]

Hopefully this will help


Service and Repair


NOTE: If the lock cylinder/key is sticking or jamming, spray lock cylinder with Mercedes Benz lock cylinder grease (part number 001 989 26 51 10). If the complaint cannot be eliminated, replace lock cylinder and key.

Removal :
Press out escutcheon (36a) using a small screwdriver.
Remove coil for transponder from lock cylinder. (Only applicable to vehicles with stage 2a [DAS 2a] drive authorization system as of 8/96)


Push sleeve (011) onto the cap (36b), turn lock cylinder to position "1" with the key. (Special Tool Part number 202 589 00 14 00 - see Tools and Equipment)



Unlock the lock cylinder by turning the cap (36b) 90°and remove.
INSTALLATION
Spray outside of lock cylinder (36) with lock cylinder grease and insert in the cap (36b).
Push key (36c) through the cap (36b) up to the stop in the lock cylinder (36). The tumblers must be drawn in fully.
Push lock cylinder (36) into the steering lock



Align indentations (arrow step 4 of Removal) in the lock cylinder (36) with the recesses in the steering lock (arrow)



Turn cap (036b) with sleeve (011) approx. 90°until it can be heard or seen to lock in position. (Special Tool Part number 202 589 00 14 00 - see Tools and Equipment)
Turn key into position (36c) "0" and withdraw/remove with sleeve (011)
Press in escutcheon (36a).
Install coil for transponder on lock cylinder if applicable