[plain OM]

Checked the fuses (other than #23) shown in the wiring diagram? The power from fuse #23 to the motor is not conveyed through the wiper switch; it's controlled by the BIU. The BIU power fuses have to be good, as well as the two fuses that are directly related to the washer motor and the wiper motor.

Checked that the connection from pin 3 of the rear wiper motor connector (D43) to body ground is intact (electrically)? The motor won't run without it.

Not unusual for there to be more broken wires that are not apparent because they're inside the wire bundle.

Also, in the photo in addition to the three butt connectors, there appears to be several wires behind that are wrapped in electrical tape. Are those still good connections?

 

[plain OM]

And does anyone have any idea what those wires actually do?

In a working system, when the rear wiper switch is turned on, the BIU connects the power from fuse #23 (upper left in the wiring diagram) at BIU terminal B21 to terminal B1, which is connected to the motor (pin 2 of motor connector D43). The wiper switch itself doesn't directly switch the power; it only grounds terminal C6 on the BIU, and that ground in effect signals the circuitry in the BIU to connect the power at B21 to B1 which goes to the motor.

When the wiper is in the parked position, the wiper motor internal switch is as shown in the wiring diagram, i.e., pin 4 of motor connector D43 is connected to pin 3, which goes to ground. When the wiper switch is turned to On and the motor starts to move, the internal switch changes over so that pin 4 is connected to pin 5, which comes from fuse #23 (upper right in the diagram). This applies power from fuse #23 to terminal B8 of the BIU.

When the wiper switch is turned to Off, the BIU doesn't cut the power to the motor. As long as there's the power from fuse #23 at terminal B8 (coming from the internal switch), the BIU keeps the motor powered. When the wiper reaches the park position, the internal switch returns to the position shown in the diagram. This disconnects the power at BIU terminal B8 (B8 goes to ground), and the motor stops running. It will start up only if the wiper switch is turned to On, or the equivalent when the washer is turned on.


I understand the wiper was working but stopped mid-sweep (10:00 o'clock position). Barring the motor itself having failed (which is possible), if the wiper switch is still at On, there should be power going to the motor from BIU terminal B1, and even if the wiper switch is Off, the BIU should be keeping the motor running until the park position because of the motor internal switch position (when the ignition switch is at ACC or ON).

I would suggest removing the rear gate trim to get access to the 4-pin wiper motor connector D43. This will enable verification of the ground at pin 3, and whether or not there's power coming to pins 1 and 2 of connector D43. The motor can also be checked for continuity between its pin 3 and a good body ground. (There have been cases of the motor failing, probably due to worn brushes, so it would be prudent to check the motor before deciding to replace the harness.)

 

[plain OM]

Did you find the catch/locking tab?

I had the panel off some time ago, but didn't pay any attention to the wiper motor connector at that time. From the wiring diagram, I think there should be a catch or locking tab on the bottom side (in the photo) adjacent to the yellow-with-green stripe, and light green, wires on the harness-side connector (left in the photo).

 

[plain OM]

At the connector on the motor side (right, in the photo), measure the resistance between each of the three (not black) wire contacts in that connector and ground. This would tell us if the wiper motor is in it's "park" position or somewhere in a "sweep", and if there's continuity (or not) through the motor.

If the motor is in the park position, there should be zero or near zero Ohms resistance between the blue wire and ground (use the lowest resistance range on your multimeter), infinite between the yellow wire and ground, and near zero between the green wire and ground. If the motor is not in the park position, there could be zero or near zero Ohms between yellow wire and ground, infinite resistance between the blue wire and ground, and near zero Ohms between the green wire and ground.

At the harness connector (left, in the photo), with the ignition at ACC, and the wiper switch at On, check for battery voltage at the light green wire and at the yellow wire (relative to ground).

To test the motor, battery voltage (+12 V) could be connected to the green wire at the connector attached to the motor (right side connector in the photo). That connection should be fused, 15 Amps max., and use adequate gauge wire.

I would highly recommend that you validate that the motor can actually move the wiper by applying external power to the motor. (just a few seconds is all you need)

• If it can... then continue to chase electrical issues
• If it canNOT... you have a seazed shaft.

When applying external power to the motor, if the motor does not run, it doesn't necessarily mean the wiper shaft is seized. If the brushes in the motor are worn out and not making contact, that too would prevent the motor from running. That's why I suggested making a few electrical measurements first.