Research time!
I measured voltages & voltage drops accross the wipers system and here are my numbers
Conditions: Dry windshield with a coat of ceramic rain repellent (like a Rainx, different brand), wipers almost stalling, blades chatter, lab power supply set to 13.6 V connected to battery, supplying up to 10 A
All voltages are approximate as they vary with battery voltage, wipier position & speed, etc.
-Voltage between gray and white wires at wiper motor - Fluctuates between 9 and 10 V depending on wiper speed
-Wiper motor +12V (white wire) to alternator +12V post - roughly 0.1 - 0.2 V
-Wiper motor low speed (gray) to body - Almost 3 V
-Voltage drop between black wire and gray wire at the connector under steering wheel: 2 - 2.5 V with delay module, 0.9 - 1.1 V when plugged without the delay module
The above numers tell me that majority of voltage drop comes from a combination of a stalk and a delay module. Wipers are hardly any faster on the HI setting (pink wire).
To get rid of ground wire voltage losses I did a "relay mod" similar to power windows where the original power wire becomes a signal and ground is switched directly. The wipers go slightly faster, but still after couple of dry wipes they slow down until they finally stop. I can even see when the internal protection trips and the motor briefly loses all power, then it restarts. I believe the motor is on it's way out...
Attached: Relay mod for wipers
