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No power to ignition system

24K views 14 replies 5 participants last post by  rowdie 
#1 ·
1985 380 sl. Car cranks, but will not turn on.


I have checked coil, green condenser wire, icm, pick up coil from ignition distributor, and no current. the only current I have is the red wire at bottom of coil coming from icm.

was thinking of replacing ignition switch next?


Not sure if it's two problems or if they are related, but instrument cluster is going all over the place when I turn lights on.

when I push turn signal to either position the light in the instrument cluster, start to flicker at the rythem of the flashers.

When I test for short with test light, fuse 12, when removed turned test light off.

also, when I crank car, the all the light on the dash go aff, with the exception of the battery light. Now my battery light never came on while car was running.
been stranded for 10 days, now. the day the car would not turn over, my battery, was fully charged. there was no drain, over night.

any impute, would really help???

My brain, is fried, just as when i had my stroke. Ouch!!!!
thanks for reading.:confused::confused:
 
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#3 ·
Can't hurt to check the OVP.

I remember my dash warning lights acting strange when the ignition switch went out. I can't remember what they did though. It can be removed without removing the tumbler and lock but I thought it was easier to remove them. You can also clean and lube the lock and tumbler while you are at it.
 
#4 ·
yes, I have checked ovp and fuse 10. looks intact. plus i tried another from a 380se not sure if interchangeable but no change.
hard to take readings when I have no current to ignition circuit. no burned wires.

thank though.
I'm still wondering what the ground wire from license bracket goes to?????
seems to be important.

o.k. thank you!
 
#6 ·
Wiring diagram

If you need the wiring diagram for your car, send me a PM and I can email to you. The file size is too large to upload. See page 107 for ignition. I would start at the fuse box and move "backwards" via the ignition lock and further to trace power according to diagram. To remove the ignition lock wiring the key should be in position one. Easiest access is by removing panel under steering wheel. Tight spot to work in, but with access to the plug to the ignition switch, you can use a multimeter to measure if you have voltage and do a continuity test of the wiring to the coil.

See this thread for troubleshooting the coil and ignition control module:

http://www.benzworld.org/forums/r-c...ing-ignition-control-switching-unit-coil.html

Hope that can get you a clue of where the culprit is!
 
#10 · (Edited)
This does not sound too serious, but I think the best approach is to get a wiring diagram from Rune and determine which elements are not working before using the shot gun approach.

- You seems to have 12 V DC to the coil and probably the ignition control module next to it.
You may want to check for a spark by using an externaly grounded sparkplug
If you have power to the coil and no spark, disconnect measure the resistance in the coil windings
- The other modules involved are:
Fuelpump relay
Measure the voltage across the fuel pump or power with 12V directly and listen for humming
Idlespeed Control Unit and Valve
This unit is probably feed by the OVP, check all fuses, failure would normally result in high idle
Depress the accelerator slightly when starting to override


Here is a wiring diagram for my 1985 500 Euro, yours is similar.
 

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#11 · (Edited)
Just an update. I have found the source of my no start issue. I went under dash, and started to go through all the wires.

I believe, a while back when they installed, my alarm, they spliced, the wire going to the ignition system.

I found this wire hidden way up in the bundle of wires running across underneath dash. It was just hanging there. It is a red wire with a black wire going through the middle. Then there was a black wire also, just hanging there loose.

I thought about conecting rd/bl with with bl. but decided that it would not be a good idea, so instead I connected the rd/bk wire to a yellow wire, and Pow! engine started right up. smoked a lot for a minute or so, I figure it was due to flooding the engine, after cranking so many times. Anyway, the smoke burned itself off.


I also changed my turn signal switch hoping that that would solve problem # 2 dash acting very erratic with lights on.


even with new turn signal switch and ground from cluster to chassis, no change.

I did notice that my radio antenna, now does not go up. So, I'm thinking perhaps tha could be the cause, or maybe the round socket that goes to the cluster.


I always, thought that if you had a short in the system that the fuse would blow, however my fuse is not blowing-burning.

can someone help me here, to figure this out? Can I drive the car like this, as when I don't use the light switch the instrument cluster works fine. It's only when I turn the lights on.


I'm nervous to drive the car like this, as I don't know if this might cause my lights to suddenly go out?


so, I'm just guessing. I've had 2 so called Mercedes experience people out, and they just take my money, and not return my calls. both made wrong diagnosis, actually, 3 made wrong diagnosis.


I have checked ovp relay, 10 amp fuse is in tact, and I used another relay, from an 84 380se, and that made no difference.


I will add, that now my battery indicator does go out, as soon as I got the engine to start it went out as it should.

sorry, for long explanation, just hoping someone knowledgeable can direct me in the right direction???? Ground to license plate? have not heard back from someone who knows, what that is a ground to??


thanks! Anybody????
 
#12 ·
how did you know your ignition switch went out? I understand erratic cluster problem, so it sounds like you were still able to turn your car on.

I did buy a spare ignition switch, however waiting to see, if I need to go that direction for erratic instrument cluster when I use my lights.

thank you for your help!
 
#15 ·
It appears you are responding to several posts one at a time. Confusing as you don't quote the post.

If you were responding to mine about the strange/erratic cluster warning lights when my switch went out I had a spare ignition switch and replaced it. The car would crank but not start. Applied direct 12V to the fuel pump still no start.

Use the Quote button when responding to a post.
 
#13 ·
thanks for diagrams, however, I had no power at all to ignition system. coil, icm, no spark. no current, even though all accessories worked. I blame it on the shop that installed my aftermarket alarm. I'm sure the wires, they spliced into, just broke apart, and I just happened to connect the right one's. Now car starts fine, but still have instrument cluster, acting erratic, when I turn my head light on, or when I use my turn signal. As, I just updated I replaced the turn signal, but no change.
thank you for your help!
 
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