Intermittent Power Failures
 

Not at good month with my 86 NA 944. It’s been one whack-a-mole after the other.

The latest is an electrical gremlin that cuts off power to various electrical components in an intermittent fashion. No sooner does the power goes off to the windows, instruments, windshield wipers, headlight motor, AC/heater fan only to return later on.

I already thoroughly cleaned the battery posts/terminals and the chassis ground near the battery. I also cleaned the headlight motor ground and tested its relay and the motor worked just fine at the time.

I’m thinking that it has to be either a ground issue, a relay, a faulty ignition switch or perhaps a bad connection in the fuse box, right?

Given that the components in question are all fused/relayed separately and the only common element is the ignition switch; doesn’t it make sense to conclude that the switch is faulty?

Your comments please!

944 ignition switches are pretty cheap and sketchy parts.
Definitely a prime suspect.

+1 or the connector on the back.

An update
 

Thought I'd post an update.

I removed the driver's seat and went to work removing the ignition switch for a closer examination. I cleaned all the terminals, tested the electrical conductivity at the various switch positions and determined that the switch is functioning normally.

However, I discovered that the tiny "buzzer contact switch" as Porsche labels it, in the steering column housing, next to the ignition switch, does not engage the key mechanism correctly. This is the switch that gives power to the door alarm relay (see link below) whenever the key is inserted in the ignition lock. Given the huge task of removing the steering column, etc. I opted to leave it alone for now. This means that the buzzer relay is always energized even when the key is not inserted in the switch. The relay constantly draws about 250mW of current so the battery will loose cranking power in a few days unless a trickle charger is used. I may tackle this problem at a later date.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/921822-door-buzzer-relay-quick-fix.html

I then moved to the wire harness plug. Many years ago I had an alarm installed and the tech had cut the positive line (red) from the battery to terminal 30 and fed it into a bypass relay. If the alarm was tripped there would be no power to start the engine. I chose to remove the alarm a while back and used a butt-end connector to join the power line together.

Anyway, I noticed a bit of play between the wire ends and the butt-connector which could have been the reason why the power would come on and off from time to time. I removed the butt-connector and used a length of heavy wire and two clamp terminals to bridge the gap. Problem solved, so far!

An update
 

Thought I'd post an update.

I removed the driver's seat and went to work removing the ignition switch for a closer examination. I cleaned all the terminals, tested the electrical conductivity at the various switch positions and determined that the switch is functioning normally.

However, I discovered that the tiny "buzzer contact switch" as Porsche labels it, in the steering column housing, next to the ignition switch, does not engage the key mechanism correctly. This is the switch that gives power to the door alarm relay (see link below) whenever the key is inserted in the ignition lock. Given the huge task of removing the steering column, etc. I opted to leave it alone for now. This means that the buzzer relay is always energized even when the key is not inserted in the switch. The relay constantly draws about 250mW of current so the battery will loose cranking power in a few days unless a trickle charger is used. I may tackle this problem at a later date.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/921822-door-buzzer-relay-quick-fix.html

I then moved to the wire harness plug. Many years ago I had an alarm installed and the tech had cut the positive line (red) from the battery to terminal 30 and fed it into a bypass relay. If the alarm was tripped there would be no power to start the engine. I chose to remove the alarm a while back and used a butt-end connector to join the power line together.

Anyway, I noticed a bit of play between the wire ends and the butt-connector which could have been the reason why the power would come on and off from time to time. I removed the butt-connector and used a length of heavy wire and two clamp terminals to bridge the gap. Problem solved, so far!