Ignition problems after jump start

TheBaron

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Hi All,

I am hoping you can help me, I have a 1984 380se. The car battery had run flat and my dad thought he would do me a favour when I was away by jump starting the car for me. His jump leads were too small to reach the battery so he connected the positive to the positive connector in the engine bay and attached the negative to the 2 areas I have pointed out in the image below. He couldn't get it started so took the battery out and got the battery fully charged for me. When he put it back in the car would turn over no problem but wouldn't start.

I came home and tryed and and the same the engine turned over but would not start. I checked it with a spark tester and the coil is not producing a spark.

I have taken the coil out to check it but not 100% sure how to do this but there is a resistance reading from both connections. I have also read that it could be the Ignition Control Module.

Any help you can give me would be much appreciated.

Many Thanks

aoAghdI.jpg
 
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TheBaron

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If there was a power surge form my Dad trying to jump start the car which part would fail first, Coil or Ignition Control Module or both.

Is it possible to fix a Ignition Control Module?

Any help would be much appreciated I don't want the car off the road for too long and don't have the money at the moment to just replace the 2 parts.

Thanks
 

television

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This just is not easy at all, where did he join the plus terminal too
 
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TheBaron

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Hi Television, There is a positive connector in the engine bay, it sticks up with a red cap on it.
 

television

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Thanks,,, the negative lead was placed very near the ignition module so maybe blown that, are there no secondhand ones around
 

brandwooddixon

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Any particular reason why you have a 3 earth wires not connected, including one that appears to go to the engine?
 

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I think they are coil connections
 

brandwooddixon

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Ah that would explain it.

Just thought that the larger of the leads looked like an engine earth strap.
 
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WG M-B

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I may well have a used module in my secret cupboard at the workshop
If you need one call me Monday morning and I will have a look
0208 863 9233
 

Triv

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I may well have a used module in my secret cupboard at the workshop
If you need one call me Monday morning and I will have a look
0208 863 9233

Secret cupboard eh?
You've blown it now!
 

Alex Crow

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Which positive terminal? Picture please.

The only correct place to connect the positive is the terminal on the battery - no other positive terminal in the engine bay is up to it, other than the one on the starter, which is impossible to connect to anyway.

The earth connection points ought to have done no harm.

It is worth testing all the basic connections here, the 4 pin plug should be 12v with ign(15), earth(31), rpm signal output(TN/TD?) and output to coil(1?). The round plug goes to rpm sensor in the distributor, and should probably measure somewhere between 500 and 2,000 ohms.
Cannot remember the coil, but should be something like 0.7 ohms LT and 10k ohms HT.

What spark tester was used, and how?
If you tested downstream of the distributor, it could be a problem there.
 
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TheBaron

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Sorry for not answering your question Alex, was away for awhile. I found out that the positive lead was connected to the positive terminal on the battery.

I used this tester Alex -http://www.amazon.co.uk/Silverline-633982-Ignition-Spark-Tester/dp/B00157O4YK/ref=sr_1_1?ie=UTF8&qid=1383831980&sr=8-1&keywords=spark+tester

I connected it to the top of the coil but no spark.

Thanks very much for the offer WG M-B is any chane you have one for sale??

Thanks All, I appreciate your help.
 
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grober

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There are also 2 ceramic mounted ballast resistors associated with the ignition coil/ ignition unit - you may have blown one or both of those.
 
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TheBaron

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Hi Grober,

Any idea where these are located?
 

grober

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If ? you have them they are often located beside the coil. Here's a picture on a W116 to show you what to look for.
Ballast+resistors_001.jpg
 

grober

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Here's a couple on an early W126. They were phased out in later models so you may not have any.
 

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TheBaron

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Thanks for that grober, I don't think I have any, especially around the coil, you can take a look at the photo on page one.

I will have a look tonight tho and see if there are any anywhere else.
 

television

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They were wired across the starter motor to boost the HV by shorting out a resistor
 
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TheBaron

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Hi Television,

Does this mean my car should have them? I checked and cannot see anything that resembles the ceramic mounted ballast resistors that was in Grobers Image.
 

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