early 944 front wiper doesn't work

[digby]

Hi All,

I have an 84 944 with a non-working (nothing happens) front windshield wiper system. This motor has been taken apart and scrubbed as well as greased. I am not really an electrical genius (nor a genius in anything else for that matter) so if anyone could point specifically to what I should try next that would be very much appreciated. Below are the steps I've tried so far based on other posts and the results.

short version: ~11.8 volts at the wiper motor connector; motor seems to spin on a test bench

long version:
I turned the key on to enable the electrical system and I switched through the windshield wiper modes while looking at my multimeter which had its probes on the plug that the wiper motor (unplugged) normally connects to. The screen read ~11.8 volts for each wiper setting with the black/negative probe touching the ground and the positive/red probe touching whichever contact was active.

Also, I placed the wiper motor on the ground and connected it directly to the battery. After a bit of trial and error, the motor did spin and hum (unless out of desperation I imagined it happening). On the other hand, the motor is silent and doesn't budge when I install it in the car and hook it up to its connector. The wiper blades have been taken off.

The motor has been scrubbed to remove a fair amount of rust and dirt from the interior but it did not look as bad as some other examples from message-boards.

So, all in all, it seems the motor is probably working; the selector switch and fuse must be working (right?) for there to be 12 volts at the connector. I just don't understand what exactly to check next and why it hasn't worked yet.

Thanks!

[944 Ecology]

Check your grounds...

[digby]

Thanks for the tip, 944 Ecology. I guess this below from 924.org is the procedure I will try to follow.

How-To Electrical Diagnosis

When troubleshooting a specific circuit, ground must still be checked even if the above steps of cleaning the grounds have been taken. This is where the multimeter shows its superiority over a test light. Use the wiring diagram to determine the last point in the circuit before ground. Use the ohmmeter function on the multimeter to check for continuity (0 resistance) between this point and the ground location. In the taillights, for example, the base plate of the light housing which the bulbs are inserted into forms a common ground for the bulbs, and you should be testing for continuity between this and your ground. The lead from this, which will be brown as previouly noted, should show 0 Ohms resistance to your grounding point. If it does not, inspect the wire and any connectors (a 7-pin nylon connector to the taillight housing, in the case of the taillights) for any breakage or damage, or any corrosion at connection points.

[djnolan]

tap on the motor housing, maybe a brush is stuck?