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I'm laboring through an electrical problem involving my windshield wipers circuit. I've done some tests eliminating potential problem areas and I'm left with what appears to be a ground somewhere in the circuit. I have some experience with multimeters but I'm not sure how to proceed.
The car: a 92 900s. The problem: about one month ago, a quick toggle of the wiper switch to sweep the windshield clear of morning dew caused the fuse to blow. I've never had a problem with the wipers in this car since purchase about 1.5 years ago (though I haven't used them much - the car has been in Los Angeles for its entire life). I was out of replacement 15amp fuses so I popped in a 20; it blew as well.
I've scanned the archives looking for ideas and guessed the problem must be the wiper mechanical assembly so I extracted that and the wiper motor. But the assembly is in great shape and shows no friction or stickiness. The motor also seems problem-free; a multimeter test shows it surging to 2.5 amps on startup before settling down to around 1.5 amps once it's running.
I have a 15 amp breaker that plugs into the fusepanel and thought it would help me find the problem device. I unplugged the headlamp motors but the breaker still trips.
Next in the chain of suspects is the relay. I pulled the wiper relay but the breaker still trips. Essentially I discovered that the circuit is tripping the breaker regardless of anything plugged in (including the wiper switch).
So this means there's a feed wire with broken insulation?
I'm using a Fluke 75 meter, switched to ohms, and attach the black lead to the car's ground and use the red lead to poke at other leads in the wiper circuit. Starting at both sides of the fuse connection, I'm getting 0.2 ohms (which is essentially the same read as when I touch the leads together).
I'm expecting one side of the fuse connection to be high-resistance (the supply side) and the other side to be low but with both sides reading low, I'm not sure what to do.
Some quick scans for solutions online show this electrical device called the ECT 2000 Powerprobe, where you plug one part of the tool into the problem circuit and then use a companion radio-signalled unit to physically trace the circuit as it scans for a drop in connectivity. It transmits a signal to the handheld scan device when it's near a break in the wire.
I'm wondering if anyone has any ideas on problem areas in the wipers circuit. The wiring in the car seems pretty clean and solid to me. I'm not finding any rotten insulation and almost everything seems stock installation with the original ziplock ties still intact in various areas where they're holding or suspending multipin connectors.
I'm looking at my Bentley wiper-circuit wiring diagram the same way I looked at my algebra book in high school; I'll do it if I have to.
Any ideas?
Thanks.
posted by 24.205.87...
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