94 318i starts then immediately dies

Sunday afternoon, my 94 318i started then immediately powered off - within a second or two, everything electric appeared to be dead, no power.
Turning the key did not restart it. No response to key on/off.
I re-tried several hours later, & got the same response. Starts then and everything turns off. Just before the retry I did a lock unlock in case it was EWS related, central locking worked. After it died again i I tried the driver's door lock, and only the driver's door locked & unlocked no central locking.
Not sure this is related but: I had just done a rear break job & put in new shocks Friday I drove about 100 miles with a few stops & restarts Saturday (amazing how much difference new shocks can make), no issues. Have not yet reinstalled the trunk liner after removing it to gain access to the shock towers.
Any ideas what to check? I should have early version EWS anti theft immobilizer. Could this be kicking in? Main relay failing?
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On 5/23/2011 5:10 AM, Grizz wrote:

Looks like it is a problem with the Main DME relay. I did some simple diagnostics today, all power was still off, had not reset like last time I tried again later.
So I started checking voltages. 12.9 on all of battery distribution block terminals in the engine compartment. 12.9 on the input lead for the fuse & relay box. Thought I had a spare relay that would work for Main DME, (from an expired e30) So I exchanged that one in, The accessories went back on and the engine cranked but did not start. Closer inspection revealed that the relay was not exactly the same, so I put the original back in, engine started and ran.
Have started stopped an driven a few times since, it went dead once, but started right up after I pulled and replaced the main DME relay. I'm ordering one and hoping that's the whole issue. (And not resetting something else by pulling that relay)
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The rest of the story ....
The car worked fine for a day, then it went dead again. I waited for the DME relay to come in the mail, hoping that was it, but it wasn't. I put in the new relay & the car stayed completely dead. Got out the voltage meter and started testing again ... turns out the connector on the end of the wire leading to the fuse/relay box tested 12.9, but the terminal bolt & nut tested at about 3 volts. The nut was tight, but a thin layer of corrosion had built up. I must have bumped the wire enough to temporarily re-establish a connection when pulling the relay the first few times. Could have been sort of related to the brake work, as the connector is near the fluid cap, may have bumped the wire or spilled a bit of fluid when working on the brakes. Got out my dremel and polished the terminal on the end of the wire and the bottom of the nut, put it back together, and works perfectly again. Now I have a spare DME relay in my toolkit in case it ever really fails ;-)
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With the plating removed, it is apt to corrode again. Grease the thing up with dielectric grease to prevent that. While you're at it, grease all the connectors and relay bases up. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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