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.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

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.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

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 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...

__________________
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