400SEL ignition problems
Thread Starter
Junior Member
Joined: May 2019
Posts: 24
Likes: 2
From: Washington, D.C
1988 300E, 1993 400SEL, 2000 BMW M Roadster; 2001 Toyota 4Runner
400SEL ignition problems
I have reached the end of the line with this issue. My '93 400SEL will not start. It has new distributor rotors and caps, new ignition coils and a new battery. It cranks but won't start. My mechanic is stumped. He says he is getting no spark from coils or distributor. The injectors are delivering fuel to the cylinders initially, so doesn't seem to be a fuel problem.
A little history: the new battery was necessary because the previous one that was one year old (MB OEM) got drained and wouldn't hold a charge. I don't drive the car much, which could contribute to the issue, I suppose. Previous similar non-start issues were diagnosed and resolved as: 1) bad distributor caps and rotors (replaced them and fixed it). 2) some sort of ignition lock issue which led to a sub-contracted "Mercedes electrics expert" jerry-rigging something in the ignition lock; also refurbished the entire radio and power antenna by Becker Autosound, as it was allegedly draining the battery when sitting. I am doubtful of this last one, but at least now I have.a refurbished radio and antenna. I am suspicious of whatever was done to the ignition at that time which may have led to the current failure (though it did work fine for several months in between). Unfortunately, I don't know what this master MB electrician did, and my mechanic at the time didn't seem to know either. The car only has 61,000 miles and has had its wiring harness replaced by PO. It is in outstanding shape otherwise, including electrics otherwise. (other than that, how did you enjoy the play, Mrs. Lincoln?)
Any thoughts?
A little history: the new battery was necessary because the previous one that was one year old (MB OEM) got drained and wouldn't hold a charge. I don't drive the car much, which could contribute to the issue, I suppose. Previous similar non-start issues were diagnosed and resolved as: 1) bad distributor caps and rotors (replaced them and fixed it). 2) some sort of ignition lock issue which led to a sub-contracted "Mercedes electrics expert" jerry-rigging something in the ignition lock; also refurbished the entire radio and power antenna by Becker Autosound, as it was allegedly draining the battery when sitting. I am doubtful of this last one, but at least now I have.a refurbished radio and antenna. I am suspicious of whatever was done to the ignition at that time which may have led to the current failure (though it did work fine for several months in between). Unfortunately, I don't know what this master MB electrician did, and my mechanic at the time didn't seem to know either. The car only has 61,000 miles and has had its wiring harness replaced by PO. It is in outstanding shape otherwise, including electrics otherwise. (other than that, how did you enjoy the play, Mrs. Lincoln?)
Any thoughts?
Out Of Control!!
Joined: Sep 2018
Posts: 14,711
Likes: 4,603
From: unbegrenzt
2017 GLE350 4MATIC
I have reached the end of the line with this issue. My '93 400SEL will not start. It has new distributor rotors and caps, new ignition coils and a new battery. It cranks but won't start. My mechanic is stumped. He says he is getting no spark from coils or distributor. The injectors are delivering fuel to the cylinders initially, so doesn't seem to be a fuel problem.
A little history: the new battery was necessary because the previous one that was one year old (MB OEM) got drained and wouldn't hold a charge. I don't drive the car much, which could contribute to the issue, I suppose. Previous similar non-start issues were diagnosed and resolved as: 1) bad distributor caps and rotors (replaced them and fixed it). 2) some sort of ignition lock issue which led to a sub-contracted "Mercedes electrics expert" jerry-rigging something in the ignition lock; also refurbished the entire radio and power antenna by Becker Autosound, as it was allegedly draining the battery when sitting. I am doubtful of this last one, but at least now I have.a refurbished radio and antenna. I am suspicious of whatever was done to the ignition at that time which may have led to the current failure (though it did work fine for several months in between). Unfortunately, I don't know what this master MB electrician did, and my mechanic at the time didn't seem to know either. The car only has 61,000 miles and has had its wiring harness replaced by PO. It is in outstanding shape otherwise, including electrics otherwise. (other than that, how did you enjoy the play, Mrs. Lincoln?)
Any thoughts?
A little history: the new battery was necessary because the previous one that was one year old (MB OEM) got drained and wouldn't hold a charge. I don't drive the car much, which could contribute to the issue, I suppose. Previous similar non-start issues were diagnosed and resolved as: 1) bad distributor caps and rotors (replaced them and fixed it). 2) some sort of ignition lock issue which led to a sub-contracted "Mercedes electrics expert" jerry-rigging something in the ignition lock; also refurbished the entire radio and power antenna by Becker Autosound, as it was allegedly draining the battery when sitting. I am doubtful of this last one, but at least now I have.a refurbished radio and antenna. I am suspicious of whatever was done to the ignition at that time which may have led to the current failure (though it did work fine for several months in between). Unfortunately, I don't know what this master MB electrician did, and my mechanic at the time didn't seem to know either. The car only has 61,000 miles and has had its wiring harness replaced by PO. It is in outstanding shape otherwise, including electrics otherwise. (other than that, how did you enjoy the play, Mrs. Lincoln?)
Any thoughts?
Thread Starter
Junior Member
Joined: May 2019
Posts: 24
Likes: 2
From: Washington, D.C
1988 300E, 1993 400SEL, 2000 BMW M Roadster; 2001 Toyota 4Runner
I also meant to mention that my mechanic says he is getting no indication that it is the crank sensor or the cam sensor, which were two things he initially thought it could be.
Out Of Control!!
Joined: Sep 2018
Posts: 14,711
Likes: 4,603
From: unbegrenzt
2017 GLE350 4MATIC
If no spark and new components (distributor, spark plugs, wires), and good cam and crank sensors, what do you think about the engine ECU? What about steering column or brake pedal interlocks? What does your mechanic think it is?
Thread Starter
Junior Member
Joined: May 2019
Posts: 24
Likes: 2
From: Washington, D.C
1988 300E, 1993 400SEL, 2000 BMW M Roadster; 2001 Toyota 4Runner
I have sent him a note and am waiting for a response. Thanks for your input.
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Thread Starter
Junior Member
Joined: May 2019
Posts: 24
Likes: 2
From: Washington, D.C
1988 300E, 1993 400SEL, 2000 BMW M Roadster; 2001 Toyota 4Runner
I just wanted to update on the final resolution. It turned out to be the ignition control unit. We found a used one and installed it. That fixed the issue and stopped the draw on the battery as well. Thanks for your help.
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