97 Nissan 200SX losing all power while driving

This problem started happening out of the blue last August, we initially thought it was a battery/alternator issue but have had those replaced and that never solved anything. The problem was sporadic, so our mechanic could never get it to happen on his own, and then the problem disappeared around October. It’s now back with a vengeance. Here are the symptoms:

While driving along in various conditions the car will sometimes do the following:

All the electrical power and gauges do down, stereo turns off, AC turns off, the works… now sometimes:

1) Even my hydrolics will go out and I can barely turn the wheel and cannot break. Need to pull the emergency break to stop. In this instance, the dashboard lights stay on… AND

2) Sometimes all the power and everything else comes back immediately like nothing bad just happened.

My mechanic tells me my batter cable is attached just fine, and he looked for a bunch of causes last time and came up empty. Any advice on where he should start this time?

Just for clarification, it’s a 200SX SE-R with an automatic transmission. The problem is happening daily now, except that it’s still at unexpected times, so the mechanic can’t reproduce it.

After the car dies and comes to a stop, sometimes I can restart it right away, but sometimes I have to let it set there for a minute, and then it cranks back up. I don’t hear any sort of hiss on the radio, so I didn’t think it’s a short, but who knows?

Your engine is stalling. That’s causing the loss of electrical power, the loss of your power steering, the loss of the AC system (the clutch to the compressor will disengage), and the loss of the vacuum in your brake booster (push HARDER).

I suspect that somewhere you have an intermittant electrical connection, but a failing fuel pump is another possibility. One other possibility is a blown fusible link. This is a fuse in insulation, it’ll go from the battery + post to the relay box under the hood, and I’ve actually seen one act intermittantly.

You need a mechanic that looks deeper.

I just read your post and it seemed very familiar. My brother has a Sentra about that age and he had a very similar problem. It turned out to be the ECM (computer). It always did this in warm weather. No problems in the wintertime. Electronics prefer colder weather over warmer weather.

Thanks for both of the replies. I’ll start by asking about the fusible link and the fuel pump, and then on to the ECM. I wish I could get it to reproduce the problem on command. The problem did reappear after a routine oil change, so I’m under the impression is really is a loose connection somewhere in th electrical system. I just put $1200 into this car between Jan - Feb, so I’m really hoping there’s any easy fix.