Test circuit for motor vehicle speed control

• US 4,565,963 A
• Filed: 04/07/1983
• Issued: 01/21/1986
• Est. Priority Date: 04/07/1983
• Status: Expired due to Term

• Current Assignee: Specific Cruise Systems, Inc.
• Original Assignee: Specific Cruise Systems, Inc.
• Inventors: Shaw, Mark L.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US06/482,834
• Time in Patent Office: 1,020 Days
• Field of Search: 324/51, 324/73 R, 324/133
• US Class Current: 324/503
• CPC Class Codes: G01P 21/02 of speedometers

Abstract

A test circuit for a motor vehicle cruise control system allows testing of the system without driving the vehicle. The cruise control system is of a type that has a vacuum servo for moving the throttle, solenoid valves for varying the vacuum in the servo, an electronic control module for controlling the solenoid valves, and a speed sensor that provides pulses to the control module corresponding to the actual vehicle speed. The test circuit is adapted to be connected between the control module and the leads extending to the various components of the system. The test circuit has series leads that connect the terminals of the system directly with the control module, except for the leads from the speed sensor. The test circuit has indicating means for determining whether or not voltage potential is present in the series leads to check continuity. An oscillator in the test circuit applies pulses to the control module that simulate pulses provided by the speed sensor.

Claims

1. For use with a motor vehicle speed control system of the type having vacuum servo means for moving a throttle, solenoid valve means for increasing and decreasing the vacuum in the servo means, selector switch means for actuating the system and selecting the speed, an electronic control module for controlling the solenoid valve means in response to the speed selected, and speed sensor means for providing to the control module electrical pulses corresponding to the actual vehicle speed, an improved test means, comprising:

a test circuit adapted to be connected to the control module and having series leads connecting terminals of the solenoid valve means and selector switch means directly with respective terminals of the control module;

indicating means in the test circuit for indicating whether or not voltage potential is present in the series leads; and

oscillator means in the test circuit for applying pulses to the control module that simulate pulses provided by the speed sensor means corresponding to a selected speed.

2. The test means according to claim 1 wherein the indicating means comprises:

an indicating lead connected to each series lead and connected through a light source to ground, so that voltage potential present in each of the series leads will energize the light source.

3. The test means according to claim 1 wherein the test circuit further comprises means for shifting the solenoid valve means independently of the control module.

4. The test means according to claim 1 wherein the test circuit has a bypass lead connecting a terminal of the speed sensor means through a light source to a voltage source, so that grounding by the speed sensor means will actuate the light source.

5. For use with a motor vehicle speed control system of the type having vacuum servo means for moving a throttle, solenoid valve means for increasing and decreasing the vacuum in the servo means, selector valve means for actuating the system and selecting the speed, an electronic control module for controlling the solenoid valve means in response to the speed selected, and speed sensor means for providing to the control module electrical pulses corresponding to the actual vehicle speed, the solenoid valve means, speed sensor means and selector switch means having terminals connected into a wire harness which has a plug connected to terminals of the control module, an improved test means, comprising:

a test circuit adapted to be connected between the wire harness plug and the control module;

the test circuit having series leads interconnecting the terminals of the solenoid switch means and selector switch means directly with the respective terminals of the control module;

the test circuit having oscillator means for providing output pulses that simulate pulses provided by the speed sensor means corresponding to a selected speed, the oscillator means output pulses being applied to the terminal of the control module that normally receives the speed sensor pulses.

6. For use with a motor vehicle speed control system of the type having vacuum servo means for moving a throttle, vacuum solenoid valve means for drawing a vacuum in the servo means and vent solenoid valve means for venting the servo means to atmosphere, selector switch means for actuating the system and selecting the speed, an electronic control module for controlling the solenoid valve means in response to the speed selected, and speed sensor means for providing to the control module electrical pulses corresponding to the actual vehicle speed, the solenoid valve means, speed sensor means and selector switch means having terminals connected into a wire harness which has a plug connected to terminals of the control module, an improved test means, comprising:

a test circuit adapted to be connected between the wire harness plug and the control module;

the test circuit having series leads interconnecting the terminals of the solenoid valve means and selector switch means directly with the respective terminals of the control module;

oscillator means in the test circuit for providing output pulses that simulate pulses provided by the speed sensor means corresponding to a selected speed, the oscillator means output pulses being applied to the terminal of the control module that normally receives the speed sensor pulses;

an indicating lead connected to each series lead and connected through a light source to ground, so that voltage potential present in each of the series leads will energize the light source;

a vacuum switch means connected between ground and the indicating lead that is connected to the series lead of the vacuum solenoid means for selectively providing a path to ground for energizing the vacuum solenoid means; and

a vent switch means connected between ground and the indicating lead that is connected to the series lead of the vent solenoid means, for selectively providing a path to ground for energizing the vent solenoid means.

7. A method of testing a motor vehicle speed control system of the type having vacuum servo means for moving a throttle, solenoid valve means for increasing and decreasing the vacuum in the servo means, selector switch means for actuating the system and selecting the speed, an electronic control module for controlling the solenoid valve means in response to the speed selected, and speed sensor means for providing to the control module electrical pulses corresponding to the actual vehicle speed, the method of testing comprising in combination:

disconnecting an output terminal of the speed sensor means from a speed sensor input terminal on the control module;

connecting to the control module speed sensor input terminal from a speed sensor input terminal on the control module;

connecting to the control module speed sensor input terminal an oscillator means for providing pulses that simulate pulses provided by the speed sensor means corresponding to a selected speed;

electrically connecting terminals of the solenoid valve means and selector switch means to respective terminals of the control module; and

turning the selector switch means on and energizing the oscillator means to provide pulses to the control module, to cause it to energize the solenoid valve means to simulate actual operation of the speed control system.