Automobile electronic circuit analyzer for detecting shorted ECM loads, including a pulsating power supply and load sensing cell

• US 5,640,093 A
• Filed: 05/23/1994
• Issued: 06/17/1997
• Est. Priority Date: 05/23/1994
• Status: Expired due to Fees

• Current Assignee: Cardone Industries Incorporated
• Original Assignee: Cardone Industries Incorporated
• Inventors: Murray, Michael T., Rodrigues, Luis F.
• Primary Examiner(s): O'Shea, Sandra L.
• Assistant Examiner(s): PATIDAR, JAY M
• Application Number:
  US08/247,707
• Time in Patent Office: 1,121 Days
• Field of Search: 324/378, 324/379, 324/380, 324/383, 324/384, 324/402, 324/503, 324/713, 324/525, 324/527, 123/416, 364/431.04, 340/524, 340/515, 340/653, 340/660
• US Class Current: 324/379
• CPC Class Codes: F02P 17/00 Testing of ignition installations, e.g. in combination with adjusting testing fuel injection apparatus F02M65/00; testing ignition installations in general F23Q23/00; Testing of ignition timing in compression-ignition engines
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00

Abstract

An automotive electronic circuit analyzer that plugs into an automobile'"'"'s electronic control module is disclosed. The disclosed analyzer includes positive and negative load sensing cells each having a series resistor coupled to an ECM load via the ECM connector and having an LED transistor for conducting current when the ratio between the load and the series resistor exceeds a predetermined value. A regulated power circuit for sinking current from the positive load sensing cells and for supplying current to the negative load sensing cells includes a timing circuit for controlling the active power pulse width so that the LEDs are illuminated with high frequency, short duration power pulses to indicate a shorted load.

Claims

1. An automotive circuit analyzer, for detecting whether a load resistance is below a prescribed value, that plugs into an automobile'"'"'s ECM connector slot in place of the ECM, comprising:

a connector for coupling the circuit analyzer to an automobile'"'"'s ECM connector slot;

a positive load sensing cell coupled to a positive load circuit in the automobile via the connector, for sensing the load resistance and illuminating an LED when the sensed resistance value of the load is below a prescribed threshold value; and

a pulsating power supply coupled to the positive load sensing cell, for energizing the positive load sensing cell with a series of high-frequency, narrow-width power pulses.

2. The analyzer of claim 1, wherein the positive load sensing cell comprises a series resistor coupled to the positive load via the ECM connector, the series resistor and load forming a voltage divider junction, an LED transistor driven by the voltage at the voltage divider junction for conducting current when the ratio between the load and the series resistor exceeds a predetermined value, the LED transistor coupled to the LED, wherein the LED illuminates when current flows through the LED transistor.

3. The analyzer of claim 1, wherein the pulsating power supply further comprises:

a protective transistor to detect the absence of battery power to the circuit analyzer and prevent current flow through the load sensing cell.

4. The analyzer of claim 1, further comprising:

a negative load sensing cell, operatively coupled to said pulsating power supply, comprising a series resistor for coupling to a negative load via the ECM connector, an LED transistor for conducting current when the ratio between the load and the series resistor exceeds a predetermined value, and a second LED, coupled to the LED transistor of the negative load sensing cell, for illuminating when current flows through the LED transistor; and

a source power circuit, operatively coupled to said negative load sensing cell, for supplying current to the negative load sensing cell.

5. The analyzer of claim 1, wherein the load sensing cell further comprises:

a protective diode connected in series with the load under test to prevent the flow of damaging current through the load sensing cell from a reverse polarity load.

6. The analyzer of claim 1, further comprising:

an adaptor connector for receiving an adaptor card, the adaptor connector having a first section coupled to the electronic control module connector and a second section coupled to the load sensing cell and the pulsating power supply; and

an adaptor card insertable into the adaptor connector for coupling signals between the first section and the second section of the adaptor connector, the adaptor card routing signals between the electronic control module connector and the load sensing cell.

7. An automotive circuit analyzer that plugs into an automobile'"'"'s electronic control module connector slot in place of the electronic control module, comprising:

a load sensing cell coupled to an electronic control module load circuit via the electronic control module connector, for generating an output signal, the output signal being in a first state when the load circuit resistance is greater than or equal to a threshold value and being in a second state when the load circuit resistance is less than the threshold value;

a display means coupled to receive the load sensing cell output signal, the display means for displaying a first visually perceptible state when the signal received from the load sensing cell is in its first state and for displaying a second visually perceptible state when the signal received from the load sensing cell is in its second state; and

a pulsating power supply coupled to the load sensing cell, for energizing the load sensing cell with a series of high-frequency, narrow-width power pulses.

8. An automotive circuit analyzer that plugs into an automobile'"'"'s electronic control module connector slot in place of the electronic control module, comprising:

a positive load sensing cell having a series resistor for coupling to a positive load via the ECM connector and having an LED transistor for conducting current when the ratio between the load and the series resistor exceeds a predetermined value;

a first LED, coupled to the LED transistor of the positive load sensing cell, for illuminating when current flows through the LED transistor of the positive load sensing cell;

a negative load sensing cell having a series resistor for coupling to a negative load via the ECM connector and having an LED transistor for conducting current when the ratio between the load and the series resistor exceeds a predetermined value;

a second LED, coupled to the LED transistor of the negative load sensing cell, for illuminating when current flows through the LED transistor of the negative load sensing cell;

a sink power circuit for sinking current from the positive load sensing cell;

a source power circuit for supplying current to the negative load sensing cell;

a timing circuit coupled to the sink power circuit and to the source power circuit for providing a signal having a frequency of about 325 Hz and having an active state pulse width of less than 10% of the duty cycle, the timing circuit signal controlling the sink and source power circuits, so that the sink power circuit sinks power only when the timing signal is in its active state and the source power circuit supplies current only when the timing signal is in its active state.

9. The analyzer of claim 8, wherein the sink power circuit comprises:

a protective transistor to detect the absence of battery power to the circuit analyzer and prevent current flow through the load sensing cell.

10. The analyzer of claim 8, wherein at least one of the load sensing cells further comprises:

a protective diode connected in series with the load under test to prevent the flow of damaging current through said at least one load sensing cell from a reverse polarity load.

11. The analyzer of claim 8, further comprising:

an adaptor connector for receiving an adaptor card, the adaptor connector having a first section coupled to the electronic control module connector and a second section coupled to the load sensing cell and the pulsating power supply; and

an adaptor card insertable into the adaptor connector for coupling signals between the first section and the second section of the adaptor connector, the adaptor card routing signals between the electronic control module connector and the load sensing cell.