CEL, lock failure, erradic idle, and no interior lights HELP appreciated!!!

[C Sport 6]

Well, its been a while since my 202 has given me any trouble, so I suppose I am due for some sort of annoyance.

The stats:
1996 C280 Sport
219K miles

The problem-
In the life of this car, I would have to say this is the largest problem it has ever seemed to have. And I mean large as in bizarre and seemingly complex. I really hope it isn't as bad as it seems.

Yesterday the CEL light came on while driving in the AM. The following evening while running to the grocery store the doors would not lock. It is now sputtering at idle- almost like the engine is about to stall out. On top of this, the interior dome lights are now not working at all.

I would assume that there must be some sort of electrical issue lurking which has led to all of these problems occurring within the 10 miles covered since the CEL came on. At least I would hope so.. I cannot imagine that all of these problems have surface independently of one another at roughly the same time.

Any advice greatly appreciated. I'll be setting up an appt. with my indy to have the car looked at, but it would be nice to gather some info from members here whom may have experienced similar issues..

[adamsry]

Well here are some tips to fix all your issues, first there is a fuse block under the hood rear drivers sided there a fuse that controls all door locks and dome lights replace that fuse.

This probably will restore the door locks and what not. Keep in mind that something caused the fuse to pop in the first place.

In the rear passenger side of the trunk there is a carpeted panel which has a electric vacuum pump is there is a vacuum leak this pump will run continuously and then cause the fuse to pop.

Vacuum leaks can also cause the symptoms that your having with the erratic idle etc etc. Under your hood on opposite of the fuse box is a vacuum line distribution thing <G> it is not uncommon for this to crack and then cause leaks id recommend that you inspect all the vacuum lines going into it and making sure that they are not damaged primarily the l fittings on the ends.

The electric vacuum pump in the rear of the car uses the clear vacuum line that connects to this junction box.

The green line controls the vent flaps in your car.

i believe the gray one is connected to the engine for the bulk of your vacuums.

Listen for hissing in this area.

The vacuum distribution block can be had from the stealer for 20 or something bucks and the little L connectors are a couple of dollars each.

The next thing i would recommend is getting electric parts cleaner and blasting out your Mass Air Flow Meter, these are notorious for failing and when you remove it, inspect it it may appear clean but trust me this works. Allow the electric parts cleaner to evaporate prior to reinstalling the MAF.

These are cheep things to try and rule out with your car.

You could have a a bad ignition coil or bad flywheel / cam sensor that could cause the CEL codes. I would try the above items as it will only take 20 min to do, these parts do fail so even if they have not yet at least down the road you have addressed them prior to having a failure

[Fizzle]

I'm Gonna Take A Whack And Say Its Altenator Related.

[xvvvz]

Do you have an original engine wiring harness? If so, isn't 96 the last year of the potentially bad harnesses? That might be something to check.

[C Sport 6]

WOW! great info adamsry, thanks a ton.

The wiring harness on the car was last replaced somewhere around 90K miles if I remember correctly- and that was appx. 6 years ago. Is it possible that the replacement harness has gone bad?

The usual w202 problem issues on this car have been addressed as needed aside from regular maintenance to keep the car in tip top shape. Front end rebuilt, rear subframe mount, rear susp. tune ups, fluid flushes, etc.. all done by the book. Since the car was new it has needed a new MAF appx. every 80K miles. Its been a while since that has given us any issues so its due for a check as well. I do not believe that we have ever replaced the alternator so that is surely another thing to consider- I tried starting the car this am to see if it would fire and it wouldnt. So I am willing to bet the alternator is toast.

Anyways, the info given here is great and if you guys can think of any other possibilities, do share. And of course when I have the car all sorted and back in shape I'll share what fixes it required for future reference.

Thanks again!

[xvvvz]

>>The wiring harness on the car was last replaced somewhere around 90K miles if I remember correctly- and that was appx. 6 years ago. Is it possible that the replacement harness has gone bad?<<

I doubt it. If you changed the original, it should last a long time.

[C Sport 6]

Had my tech run the CEL code;

036 02s (Lambda) control system. Lean stop/mixture too rich

P1400 EGR Switchover Valve

P0170 Fuel trim malfunction

Going to bring the car in first thing after the holidays for the fix, along with a tune, and to have the lock/dome light issues sorted. Thanks for all the tips guys!