Abstract: An electrical diagnostic tool for in situ testing of a tone wheel sensor mounted in proximity of a rotatable tone wheel. The tone wheel sensor produces a periodic pulse train signal as the rotatable tone wheel is rotated. The tool has a signal conditioning block for receiving the periodic pulse train signal and generating therefrom a logic-level signal having a frequency. A digital counter has a plurality of outputs and is clocked by the logic-level signal. A plurality of LEDs controlled by the digital counter are used to determine the operational condition of the tone wheel sensor by sequentially illuminating the LEDs at the frequency and in accordance with a counting sequence of the digital counter.

Abstract: A vibration diagnostic instrument for use by an automotive maintenance mechanic. The vibration diagnostic instrument includes a sensor, which senses vibrations and generates a sensor signal in response thereto, and a controller. The controller is coupled to the sensor and receives the sensor signal. The controller includes a transmitter portion that generates a diagnostic signal responsive to the sensor signal. The transmitter portion transmits the diagnostic signal over radio waves so that it may be received by an appropriate receiver, such as a conventional FM receiver.

Abstract: A vibration diagnostic instrument for use by an automotive maintenance mechanic. The vibration diagnostic instrument includes a sensor, which senses vibrations and generates a sensor signal in response thereto, and a controller. The controller is coupled to the sensor and receives the sensor signal. The controller includes a transmitter portion that generates a diagnostic signal responsive to the sensor signal. The transmitter portion transmits the diagnostic signal over radio waves so that it may be received by an appropriate receiver, such as a conventional FM receiver.

Abstract: A method to diagnose electrical failures of remotely driven inductive loads as well as the failures of electrical connections between a controller and a remotely located power module. Circuitry for diagnosing the fault condition of a plurality of remote inductive loads driven by a master module over a corresponding plurality of connection lines. Diagnostic information is mixed or intermodulated onto the connection line for a control signal of a sequential subsequent one of the loads and is transmitting over the connection line from the remote load to the master module for receipt by a controller in the master module. The control signal was not responsible for driving that particular load from which the diagnostic information was taken. The loads are sequentially driven so that the diagnostic information is multiplexed onto the connection lines which aids in helping the controller to recognize the fault condition.

Abstract: A circuit is provided for detecting a short circuit in a remote low-side driven load wherein a single conductor is used to both transmit a control signal from a microprocessor controller through a local driver to the remote driver of the load and also to transmit fault signals from the remotely driven load back to the control means. A control signal is transmitted from the microprocessor controller through a local driver circuit to a remote driver circuit on a single conductor. A short circuit at the remote load causes a fault signal to be latched for later detection by the microprocessor and a short circuit at the local driver is immediately detected.