Usage:
Introduction
Many wiper motor problems can be traced to a poor or bad ground. This instruction provides the necessary information to troubleshoot a wiper motor with grounding problems. It also shows how to properly connect the ground wire.
Reference: Parts Book and Service Manual
Wiper Connections
All wiper motors are grounded through the mounting. Paint on the mounting surface can cause the motor not to operate or to operate intermittently. When troubleshooting a wiper motor circuit make sure the motor is properly grounded.
Use a 6V7070 or 6V7800 Multimeter to measure the voltage from a good cab ground to the wiper motor housing. With the wiper motor switch "ON" (in either low or high speed), a voltage reading more than 0.6 volts, on a 24 volt system, indicates a poor ground.
The latest wiper motors have five wires. Four wires go to a connector and the fifth wire may be connected to a good cab ground.
If during a troubleshooting procedure, a poor ground is indicated, the fifth wire ground should be connected.
This wire is also identified by a tag "FAILURE TO OPERATE MAY REQUIRE CONNECTION TO A GOOD CAB GROUND".
The following illustrations show the electrical path for the four functions provided by this motor.
Wiper parked or "OFF".
Low speed.
High speed.
Wiper parking.