HI. I'm trying to troubleshoot my 1997 subaru legacy 2.5l rear windshield wiper. I have multi meter but I am unsure if I am using it properly to check if I am getting proper amount of power to the motor to eliminate relays and switches. I'm unsure if it is the motor or the other components. Where do I start? The motor assembly is removed from the back window. Please some direction in the right way would be awesome. Thanks
2 Answers
Set the volt meter to DC volts so that it will read 12.5 volts + or -. Turn the vehicle on to accessory and turn the rear wiper. Check for 12 volts at the power connector at the the wiper motor. You will have to have the black lead of the voltmeter connected to a ground. If there is no voltage the problem is before the power gets to the wiper motor. If you have power at the connector and the wiring is good going to the motor then I would look at replacing the motor. If you are uncertain that you are using the volt meter correctly practice using it on the terminals of the car's battery.
TheSubaruGuruBoston answered 6 years ago
Nice generic response, Bob. But more specifically for the Subaru rear motor/drive system: The most common problem is that droplets of salty water get into the drive axle that the wiper blade attaches to. If the motor is turned on while the drive "axle" is thus frozen, the motor is strong enough to rip a tooth or two off the inner nylon drive gear of this axle. So if you send power to the motor...hear it humming?...but the axle doesn't turn, turn off immediately and unscrew the drive housing, carefully separating the back plate from the assy. Don't lose the spring if it pops off. Are all the teeth in place on both the pinion and drive nylon gears? If not, throw the whole thing away and chase a used one from a salvage yard. If the gears teeth are all there, carefully remove what you can, and then GENTLY (if possible) pound out the axle that's frozen into the housing. You'll eventually get it out. Then sand the crusty axle and lube with thick grease (there'll be some leftover in the housing assy), and reinsert back into the assy, checking for free rotation. Align and mount the gear pair (and any spring), and attach the backing plate. Operate the system in space to test. Remount the assy onto the hatch and connect the power again. Mount the wiper blade in any position, and operate, watching the orientation of the blade's motion, as it is randomized by your work. Reset the blade so that it parks about 2:30 or 3 0'clock to create maximum visible surface area from the driver's rear view mirror. If I recall that's about 10AM to 3PM sweep. So you see that the nylon drive gearset is made to sacrifice itself to prevent the motor from burning out...and perhaps creating a fire hazard. Yet that does mean that once you lose a tooth you'll need to trash the whole system. I've been known to really soak a frozen assy with a penetrant overnight and twist and pound the axle out with much force, but you have to be careful to not pound flat the axle's threaded end or you'll not be able to reattach a wiper blade. If you get frustrated and pound the thing apart just remember that these are only $50 eBay items. Have fun.