Any help or insight would be greatly appreciated. My 400e, V8, gas-burner,with 207K miles,has had the check engine light on since 203K miles with no noticeable after effects, other than my extreme case of obsessive compulsive disorder that can not seem to allow this to go on much longer. I will be redeploying to Iraq soon and I would certainly like to solve this little red light situation if I could - with your help of course. At times, with the check engine light on and normally the first start of the day, I detect a very slightidle miss that seems to improve once the car has been driven a while. Thereis no noticeable increased fuel burn under this condition and I normally average 18-20 MPG in town and 25-27MPG on the road.

I recently had the battery tested and it was only putting out 10 volts at 225 amps, so Ireplaced the 10 year old battery and when I restarted the car for the first time, the check engine light was off, only to return after about five or sixstop and go starts of the engine and probably only 50 miles or so total elapsed. I can only remember the check engine light going off on it's own one time while I was driving under normal conditions to only return again some time later with the car having nonegative operating conditions thereafter. Don't know if that's any help to anyone other than I want to include any and all idiosyncrasies that may lead to the culprit. Guess you noticed by now that I am too cheap to havethe dealership look at it.

So, all I have done thus far is purchase the hippy-dippy aftermarket 38-pin diagnostic reader off Ebay and let me tell you that's a piece of work.I include the following details in hopes of somebody out there having experience with this tool and can instruct me how to do it the right way. The instructions and the seller tells me to connect the red, black leads to powerand ground socket respectfully with the yellow lead as the individual prober of the remaining pin sockets which correspond to the systems as depicted in the diagnostic user manual. I get nothing but a constant led light on when I check these circuits as I depress the button down for the first time. The only way to remove the reader red light is to depress the normally-open/ normally-closed button. What I have been told thus far is to place the yellow lead into one of the suspected pin sockets corresponding to the car systemand I should either get asingle flashing red led reader light indicating a normal system function or either I get a series of pulses indicating a code that has probably turned on the Red Check engine light. Well,all I get is just what I indicated above, seems to work like a common light switch on your wall in your home i.e. with red and black pins powered, push down on button, reader light comes on, push down on button again and reader light goes off.Having been sent a factory diagnostic user manual with this gadget, surely this thing does work and I would be most appreciative if someone with experience could get me out this "proverbial ditch". You're probably saying by now that I should have invested the money spent on the reader and applied it to the dealerships diagnostic testing fee Well, I still have my heels dug in and I certainly hope you great folksout therecan provide me with answer. Thanks again, Chief Warrant Officer Four (CW4) William G. Timmons CELL 662-687-0703 or william.timmons@us.army.mil

 

Your car is pre obd2 so go on over to the E section on mbworld.org
400E for help with the pin readout problem.The reason the light went off and cleared was because of the battery disconnect,that will erase a light but not clear the code or problem.That is why it came back on after several drive cycles.
OBD1 system that you have only showed failures in a system related to emissions,unlike OBD2 that shows actual out of range problems and malfunctions.
You can't ignore it just because it is bothering you.If it is a bad O2 sensor you can fry your cats.If it is a bad cat you can cause internal engine problems.If you can pull the code I have a list of Mercedes obd1 codes that will point you in the correct direction.
ohlord
RD2 USN Vietnam
We salute your service.
Lost a great friend WO Jack Morgan 2/27/91 Helicopter pilot.Keep safe.
ohlord

 

You are a scholar and a gentlemen. Thanks for the speedy response. Your insightful help with thisforum is a tremendous help and it is evident throughout as I researched my problem in the archives. Thanks again, it is comforting to know, since mine is an OBDI system, that I only have few areas in which to troubleshoot my red light.

CW4 William "Greg"Timmons,Apache & Kiowa Warrior Pilot

 

Jack flew Apaches,He was on his way out in Storm in a Blackhawk an hour before the cease fire in 91.Ours prayers are with you and yours on a safe mission.
Rob aka ohlord