Noah S.

Well I finally got my car on the road thursday!!! After waiting for 8 months it felt great to be driving my car.

Two day later(today) as I was getting on to 495 South, my car suddenly died... Abruptly, all power shut off as I shifted into 4th gear. Everything electrical died instantly, except the stereo which is hard wired to the battery. The battery is still alive and well but anything electrical in the car won't work, it's like there is no battery even in the car. Except for the working stereo of course. Can you guys offer any explaination as to what might cause this and how I can fix it? Thanks a lot!

-Noah

Water944t

Sounds like you should start with the fuse box, and go from there.

Check your DME relay too. Check for voltage to the starter, and to the coil. (Be careful)

Check to make sure your negative battery cable is grounded and tightened down well.

Check in the passenger footwell and make sure your DME-KLR are plugged in and no loose connectors are present.

Maybe the ignition switch is bad?

Hope those ideas help.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Noah S.

Well, I checked all of the fuses... no luck there.

As for the ignition switch, I don't think it would be that as the interior lights and headlights don't work. I could be wrong though?

Oh well, I'll poke around with it more today, where is the DME relay?

If anybody else has any suggestions that would be great, I really want to get back on the road... My 300E just spewed its coolant all over my driveway. I'm not having much luck with german cars this week.

Thanks for any help you guys can give me!

Noah S.

I just thought of another thing... When the car died the headlights were on. So naturally the headlights were stuck in the on possition, even after I turned them off. When we got the car back to my house and unloaded it from the tow truck the headlights were down. Doesn't that mean at some point between where the car broke down and my house the car was getting power?

I also checked the grounds and they seem to be fine.

Maybe I'll go do my front wheel bearings while my car is out of commision.

Wish me luck guys, I'll need it! <img src="graemlins/jumper.gif" border="0" alt="[jumper]" /> <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />

Skip

Had a similarly strange problem a few years ago - turned out to be the alternator to starter hot lead was shorted to the block. Maybe worth a try.

Could also be a really bad ground.

Good Luck!

Skip

IceShark

I don't believe there is any way you can get the headlights to go down without either power or turning the manual ****. This would lead me to believe that whatever is bad got shook back together to make the electrical connection on the trip home.

That should rule out fuses (they melt a big chunk of material apart so shouldn't be long enough to shake back together). Is the stereo also hard wired to the negative battery post or to the frame? If to the frame then your ground has to work at least a little and some of the equipment should work.

So, the problem must be somewhere in the positive power supply. Trace it from battery to fuse box and go from there. Maybe follow the clock power as that is supposed to be on at all times unless you disconnect the battery. A good bet is in the fuse box. Relays can fail in an intermittent way, but I don't think there is any one relay that is responsible for turning on all power supplies under all conditions.

I doubt it is a short because if the short was bad enough it would kill your battery and probably start something on fire or at least melt the offending component apart. Which means nothing, like your headlight motor, should have worked after the initial event. And if an intermittent short some things should work when it is not shorted.

So, dig out the 'ole voltmeter and find out where along the way power stops.

icat

[quote]Originally posted by Noah S.:
<strong>Two day later(today) as I was getting on to 495 South, my car suddenly died... Abruptly, all power shut off as I shifted into 4th gear. Everything electrical died instantly, except the stereo which is hard wired to the battery. -Noah</strong><hr></blockquote>

OK, I know you guys are going to believe I only have one answer for everything, but...
If the Crank or Speed Reference Sensors come loose while your driving, you'll get the exact same results. Make sure the plugs for the sensors are well seated. If they wiggle, there too loose!

Good luck,
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Bri Bro

icat, the sensor would not stop the headlight from closing. I bet you have a problem with one of the battery leads. Since the radio was still working, the negitive radio lead still had a connection to the battery ground. Take a good look at the positive battery lead, I am guessing the radio connects directly to the battery post and the radio ground is from the chassis.

Noah S.

I just took out the DME relay and connected 87b with 30 and viola the fuel pump came on... So it must be getting power.

I really don't think the DME relay would cause loss of electricity to EVERYTHING except the stereo which is hardwired to the battery would it? Even the cigarette lighter and clock don't work(the battery if fully charged).

I'm going to go see if there is any current going to the alternator/starter in a few... I'll try to see if it will turn over by bypassing the starter soleniod too.

Let me know what you guys think, I'm pretty new to all this and... well basically clueless. I'm trying my hardest though <img src="graemlins/c.gif" border="0" alt="[ouch]" /> How else can you learn right?

ERAU-944

come on! just try the DME relay its like 17 bucks or something from ians... if you're going to drive a p-car learn to try the cheap stuff first!!! dont fool around with the other stuff till you run out of cheap options! dme problems with my car were elusive, i thought i had a bad fuel pump, but its the dme... which controls tach, and most other things, so try the dme relay fist. good luck!
- Mike

FLUFF

I had a similar problem with my 944 once- multiple corroded leads in a single battery connector were to blame. The connector screw doesn't necessarily make good contact to ALL the wires.

PS radio will work on a pretty flat battery - though not much else will.

FLUFF

PPS check battery fixed and lead cannot short to bonnet (hood).

steve&reeds boogie car

Main DME Relay goes bad in these cars. It controls all power. Look in your fuse box. Take it out and remove cover. Mine had a solder joint fail. Resoldered and has been fine for about 80k miles.

NeilW

Noah/Everyone,
Did this one ever get resolved? This is very similar/the same as my problem whereby the car seems to intermittently have no electrical power. Mine is RHD so the battery is in the boot/trunk. I suspect it could be either the positive feed or an internal fuse box problem.

Cheers,

Neil

Campeck

CHECK YOUR F***ING GROUNDS!
atleast it wasnt a timing belt..which is usually what makes cars "die" on the highway.