Aenyone

1989 944 N/A

I was having occasional start problems, a click and a hum, but no turnover.
After turning the key off then back on, sometimes it would start.
Thinking it may have been the starter, I had a friend take his out of his 944 and into mine. Now, it won't start at all no matter how many times we turn the key off and on. Put the original starter back in, and no luck. Just a click and a hum.
We also jumped the battery from another vehicle, to eliminate a bad battery option. No change.
Is the ignition switch my next option?

Yarf

The ignition switch supplies 12VDC to the the starter solenoid. If you hear a click then the ignition switch is supplying the 12 volts to the starter solenoid via a red and black wire which is the smaller of the three wires connected to the starter solenoid.
The starter case is grounded via the starter bell housing bolts and the bell housing grounded via a ground black cable connected to a stud at the top of the bell housing, this ground wire is connected to the negative side of the battery. 12VDC is supplied to the starter via the largest cable which is connected to the plus battery terminal. The third wire on the starter (medium size) is connected to the alternator output. If I understand your and your friends starter acted the same (click and hum).
I would make sure the the ground cable on top of the bell housing is in good condition it may need to be cleaned. There are 2 ground studs on the top of the bell housing which are hard to see and reach, the heater hose and control valve are in the way it may be easier to disconnect the short heater hose at the engine block and move the heater control valve just enough to see the ground studs ( be carefull there is a vacum control line connected to the heater control valve). Place some rags over the TDC inspection opening in bell housing to keep any fluid or parts falling into the clutch/fly wheel (That would not be good). If the grounds are good then it is possible that the ignition switch has bad starter contacts or the red and black starter solenoid wire is in poor condition. You could momentarily touch a jumper (12 awg) between the large starter terminal (12VDC) and touch it to the the smallest starter terminal (red and black wire). If the starter works then the ignition switch or the red and black wire are suspect. Make sure the car is stable on jacks and in neutral.
Hope this helps
Keith

Grandpa#3

Hi Aeyone, Yarf gave you a great run down on the starter and grounds. If you work through his write up and still have a No Start it could be the Ignition Switch Module forward of the key. I'm old, so I had to remove the steering wheel, trim, gage surround, and gages just to see where the module was located and how to remove it. The whole Ignition Assembly is held onto the Steering shaft by two halves that were bolted together with two torque bolts that the heads are sheared off from the bottom. I could not get a drill bit from the underside to go straight up into the bolt to use an easy out. Scrub that idea. My next idea was to use a cut off wheel in my drill to cut a slot across the top (end) of the bolts and turn them out with a stubby screw driver. I got the inspection mirror out and looked at the back side of the electrical switch module. There is a plug with all the wires that has to be pulled off the module, got that pulled (careful you don't pull out the wires) and there are two screws holding the module to the ignition assembly. Long story short. I broke off the handle on my shortest stubby screw driver, used a SHORT long nose vise grip and was able to turn out the screw next to the steering shaft. The other screw was a snap. I plugged in the new ignition module, used a cross point screw driver to turn to start and WOW the engine started. Installed the module to the ignition assembly. While the gage cluster was out I replaced all the light bulbs. The gage cluster trim has two hidden screws, one above and one below the trip reset button at the vent edge. I hope this helps if you have to use it. The link below gives the module wire lay out for the plug. The second link will show what the Ignitio Assembly looks like.

http://forums.pelicanparts.com/porsc...87-944-na.html

http://nasaforums.com/viewtopic.php?f=40&t=20345

Cheers,
Larry

Aenyone

Guys, thanks a ton for the info. I'm going to chase it down tomorrow.
Grandpa, fantastic links and info.

KuHL 951

When my ignition switch was bad it had a 'hot start only' problem. If I drove in heavy traffic in the Summer or hit boost over and over on a run it would not even click and I would need a push. All the dash lights would light but no noise at all. I replaced the switch finally and it never did it again.

Steve944

had same problem on 86 na 944,changed out starter, removed dash and changed out switch and two relays in fuse box hooked up starter button, used for months, turned out to be a bad plug behind the power booster that was the problem, two wire pin, one to alt, one to starter

Aenyone

Guys, thanks for the info. The culprit was the ground from the battery. Twelve dollars later, back up and running.