This is my second post regarding this problem.

I have a 1989 300E that is doing something that no MB Tech, Indy Tech, or standard Mech has heard of before.

My MB runs fairly well. All in all it is a sound car and I have fallen in love with it since I purchased it 2 years ago. The problem appears when I turn the car off (completely). This is when the "Check Engine" light comes on usually 2 to 3 minutes later. The strange part to this is when I turn the car back on the check engine light will go out in about a minute and stay out for the duration of my trip.

I originally thought this was a result of the new altenator installed in my car a day before all this began. I took it back to the Firestone that installed it and they ran a diagnostic on the battery, starter, and altenator. The results came back with everything operating within their normal ranges with the exception of the battery which was a little low on CCA's (about 443, s/b 700). The mech there suggested that it was a problem with the car's computer which I disagree with because if this was the case the check engine light would stay on regardless if the car is on or off.

I then began checking under the hood for any loose wires or cables and if there were any faulty or exposed wires. Nothing that I could see with my eyes. I then began pulling the fuses one at a time in an attempt to isolate a fuse that may be the culprit. fter going through all the fuses the light never went out.

I am at my wits end with this because I am draining my battery everytime I turn my car off (Imagine that).

I would like to thank everyone in advance for any and all feedback in regards to this problem.

Shouldn't be able to happen unless the car is a California version.

I guess a sticking over-voltage relay "could" cause that to happen.

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Thank you very much for your reply.
My car was originally purchased in Connecticut which I bought from the original owner.
Could it be possible for a vehicle with California standards be sold on the East coast?

Possible, yes.

PM or e-mail me your VIN#









Have a great day.

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I don't have an answer for you...but this happened out of nowhere on the CE about 6 months ago.... somehow the problem corrected itself or went away....

I didn't notice the issue until fall when the it started getting darker earlier... my wife drives this car...

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

I am positive my car is having fun with me.

Today after a trip and parking my car, I decided to take pictures of the instrument panel to show the light out while the car is running and after turning the car off. Of course, after turning the car off the light never came on. I was excited thinking that the gremlin in my electrical system had gone.

It stayed off for 3 1/2 hours until I got back in the car to drive somewhere. When I returned and shut the car off, the light came on.

Because of this happening, I am now thinking it may be a relay/switch that is going bad instead of a constant flow of power from a wire or part. Am I thinking correctly? Of course I have never claimed myself to be a Master Mech by any means, hardly a novice DIY'er. Should I take this occurence as a problem with a switch?

Another thing I noticed today was a sound, not quite a click but more of a dull knock coming from the passenger side of the car near the foot well. It did it continuously in 3 second intervals. Where is the Over-Voltage relay located? I thought I read on the forum here that it may be under the floor panel on the passenger side.

I am attaching a photo of the Battery, Starter, and Altenator test conducted at the Firestone that installed my altenator.

Thanks again to everyone for all of your advice and feedback. I will take everything offered into consideration and give the feedbacks of the results.

Attached Thumbnails

 

I got your VIN#, checking it now.

This is very odd, it has code "040 - C 220 Canada Special Edition"...

This is a North America vehicle, it appears to be a special order Canada car.

Trying to check with my Canada contacts for further data.

I wonder if it could be as simple as a failing ignition switch. If the engine electronics are powered up while the engine is not running, the CEL is on - at least some of the time. How well does the behavior match what you would see if you turn the key to the "run" position, but don't start the engine. We've seen ignition failures before, though those were all along the lines of accessories/windows/etc. don't always work when the car is running.

Have you tried pulling fuses to see if/which one extinguishes the CEL? That and some time staring at a wiring diagram could start to narrow down what is causing the CEL to illuminate.

My rambling $.02,

- JimY

whunter: If my MB was manufactured for North American specs would it make a difference if it is a "Canada Special Edition". By the way, this is great information to know. From my VIN review, I just got the history on the car since it was purchased in Connecticut. Thank you!

jcyuhn: When you had this similar problem, what measures did you take to prevent your battery from draining? How long did it take for the electrical issue to go away?

lee polowczuk: I was also thinking it could have been the ingnition switch. When turning the car off, I would turn the ignition to postion# 1 (or accessory position) to see if the CEL would not illuminate. That didn't work. I also tried turning the ignition to that postion after driving instead of turning it to the off position to see if that would work but no dice. Yes I did pull fuses one by one with unsuccessful results. In my novice diagnosis I had ruled out the ignition switch. Again if I am thinking in the wrong direction, please correct me.

I just got my hands on an electircal schematic. After I start making sense on how to follow it I will try following the wires in the car. I think then I will really need input from this forum.

The ignition switch sounds like a likely culprit or the opinion of MBDoc.

Must be a freaky wire that periodically makes contact imitating start up. Your car's check engine light probably goes on moentarily upon start up and a few seconds later goes off. That could mean that the relay MBdoc mentioned is freaky. Energised when it shouldn't.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

Apologies for the late post on this topic. I have been out of town on business.

The culprit has been identified. M.B. Doc, you were so correct! It was the Over Voltage Relay. I am ashamed to say that I never realized those relays were back there in the battery well.

First I pulled the 10A fuse from the relay. As soon as I did that the CEL went out. After inspecting the fuse and seeing no breaks in the contacts. I decided to replace the fuse anyway. When I inserted the fuse back into the relay, the light came back on.

I then disconnected the relay and hit it against my hand about 10 times and re-attached the relay. The light came back on. I have the new relay on order and should be delivered in a few days.

I would like to take this time to thank everyone for their valuable information. It has proven invaluble.

Cost of 1989 300E - $2,500

Investment to get car road ready - $900

Engine & Tranny replacement from car being stolen - $3,700

Forum with tons of helpful information - PRICELESS!!!

2 Points for MBDOC ! I am glad your car is resolved now.

Your car was stolen and had to have the engine and trans replaced? Is there another thread with the details??

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD