Wiring Systems - Introduction: Diagnosis Chevrolet SSR I

Circuit Testing

The Circuit Testing section contains the following diagnostic testing information. Using this information along with the diagnostic procedures will identify the cause of the electrical malfunction.

1. «Using Connector Test Adapters»(ref-187796-S25759239432005090100000)
2. «Probing Electrical Connectors»(ref-187796-S22377778512005090100000)
3. «Troubleshooting with a Digital Multimeter»(ref-187796-S10210330282005090100000)
4. «Troubleshooting with a Test Lamp»(ref-187796-S02869545752005090100000)
5. «Using Fused Jumper Wires»(ref-187796-S27790342172005090100000)
6. «Measuring Voltage»(ref-187796-S15620711862005090100000)
7. «Measuring Voltage Drop»(ref-187796-S21763144752005090100000)
8. «Measuring Frequency»(ref-187796-S36759798892005090100000)
9. «Testing for Continuity»(ref-187796-S08309502862005090100000)
10. «Testing for Short to Ground»(ref-187796-S20152067332005090100000)
11. «Testing for a Short to Voltage»(ref-187796-S03552234042005090100000)

Using Connector Test Adapters

Note. Do not insert test equipment probes (DVOM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616 GM-Approved Terminal Test Kit or the J 42675 Flat-Wire Probe Adapter in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals. When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal test adapter choice is the correct size for the connector terminal. Do not visually choose the terminal test adapter because some connector terminal cavities may appear larger than the actual terminal in the cavity. Using a larger terminal test adapter will damage the terminal. Refer to the J-35616 GM-Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved Terminal Test Kit for the correct adapter along with the connector end view for terminal size.

Troubleshooting with a Digital Multimeter

Note. Refer to Test Probe Notice in Cautions and Notices.

The J 39200 instruction manual is a good source of information and should be read thoroughly upon receipt of the DMM as well as kept on hand for future reference.

A DMM should be used instead of a test lamp in order to test for voltage in high impedance circuits. While a test lamp shows whether voltage is present, a DMM indicates how much voltage is present.

The ohmmeter function on a DMM shows how much resistance exists between 2 points along a circuit. Low resistance in a circuit means good continuity.

Diodes and solid state components in a circuit can cause a DMM to display a false reading. To find out if a component is affecting a measurement take a reading once, then reverse the leads and take a second reading. If the readings differ the solid state component is affecting the measurement.

Following are examples of the various methods of connecting the DMM to the circuit to be tested

1. Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while you perform other operations or test driving. Refer to «Probing Electrical Connectors»(ref-187796-S22377778512005090100000) .
2. Disconnect the harness at both ends of the suspected circuit where it connects either to a component or to other harnesses.
3. If the system that is being diagnosed has a specified pinout or breakout box, it may be used in order to simplify connecting the DMM to the circuit or for testing multiple circuits quickly.

Troubleshooting with a Test Lamp

Tools Required

J 35616-200 12-Volt Unpowered Test Lamp

Note. Refer to Test Probe Notice in Cautions and Notices.

A test lamp can simply and quickly test a low impedance circuit for voltage.

The J 35616-200 is Micro-Pack compatible and comprised of a 12-volt light bulb with an attached pair of leads.

To properly operate this tool use the following procedures.

When testing for voltage

1. Attach 1 lead to ground.
2. Touch the other lead to various points along the circuit where voltage should be present.
3. When the bulb illuminates, there is voltage at the point being tested.

When testing for ground

1. Attach 1 lead to battery positive voltage.
2. Touch the other lead to various points along the circuit where ground should be present.
3. When the bulb illuminates, there is ground at the point being tested.

Testing for Continuity

Note. Refer to Test Probe Notice in Cautions and Notices.

The following procedures verify good continuity in a circuit.

With a Test Lamp

1. Remove the power feed (i.e. fuse, control module) from the suspect circuit.
2. Disconnect the load.
3. Connect 1 lead of the test lamp to 1 end of the circuit to be tested.
4. Connect the other lead of the test lamp to battery positive voltage.
5. Connect the other end of the circuit to ground.
6. If the test lamp illuminates (full intensity), then the circuit has good continuity.

Testing for Short to Ground

Note. Refer to Test Probe Notice in Cautions and Notices.

The following procedures test for a short to ground in a circuit.

1. Remove the power feed (i.e. fuse, control module) from the suspect circuit.
2. Disconnect the load.
3. Connect 1 lead of the test lamp to battery positive voltage.
4. Connect the other lead of the test lamp to 1 end of the circuit to be tested.
5. If the test lamp illuminates, there is a short to ground in the circuit.

Testing for a Short to Voltage

Note. Refer to Test Probe Notice in Cautions and Notices.

The following procedure tests for a short to voltage in a circuit.

1. Set the rotary dial of the DMM to the V (DC) position.
2. Connect the positive lead of the DMM to 1 end of the circuit to be tested.
3. Connect the negative lead of the DMM to a good ground.
4. Turn ON the ignition and operate all accessories.
5. If the voltage measured is greater than 1 volt, there is a short to voltage in the circuit.

Testing for Intermittent Conditions and Poor Connections

Tools Required

1. J 35616 GM-Approved Terminal Test Kit
2. J-38125 Terminal Repair Kit. See «Special Tools and Equipment»(ref-187796-S23025476162005090100000) .
3. J 42675 Flat-Wire Probe Adapter. See «Special Tools and Equipment»(ref-187796-S23025476162005090100000) .

Most intermittent conditions are caused by faulty electrical connections or wiring. Inspect for the following items

1. Wiring broken inside the insulation
2. Poor connection between the male and female terminal at a connector.
3. Poor terminal to wire connection-Some conditions which fall under this description are poor crimps, poor solder joints, crimping over the wire insulation rather than the wire itself and corrosion in the wire to terminal contact area, etc.
4. Wire insulation which is rubbed through-This causes an intermittent short as the bare area touches other wiring or parts of the vehicle.
5. Refer to «Inducing Intermittent Fault Conditions»(ref-187796-S40174375812005090100000) in order to duplicate the conditions required in order to verify the complaint.
6. Refer to «Testing for Electrical Intermittents»(ref-187796-S27837642312005090100000) for test procedures to detect intermittent open, high resistance, short to ground, and short to voltage conditions.
7. Refer to «Scan Tool Snapshot Procedure»(ref-187796-S27575319032005090100000) for advanced intermittent diagnosis.

Testing for Proper Terminal Contact

It is important to test terminal contact at the component and any inline connectors before replacing a suspect component. Mating terminals must be inspected to ensure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation.

Contamination may be caused by the connector halves being improperly connected. A missing or damaged connector seal, damage to the connector itself, or exposing the terminals to moisture and dirt can also cause contamination. Contamination, usually in the underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit.

Deformation is caused by probing the mating side of a connector terminal without the proper adapter. Always use the J 35616 when probing connectors. See Special Tools and Equipment . Other causes of terminal deformation are improperly joining the connector halves, or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact causing an open or intermittently open circuit.

Testing for Electrical Intermittents

Perform the following procedures while wiggling the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test equipment.

1. «Testing for Short to Ground»(ref-187796-S20152067332005090100000)
2. «Testing for Continuity»(ref-187796-S08309502862005090100000)
3. «Testing for a Short to Voltage»(ref-187796-S03552234042005090100000)

If the fault is not identified, perform the procedure below using the MIN MAX feature on the J 39200 DMM. This feature allows you to manipulate the circuit without having to watch the J 39200 . The J 39200 will generate an audible tone when a change is detected.

1. Connect the J 39200 to both sides of a suspected connector (still connected), or from one end of a suspected circuit to the other. Refer to «Troubleshooting with a Digital Multimeter»(ref-187796-S10210330282005090100000) for information on connecting the J 39200 to the circuit.
2. Set the rotary dial of the J 39200 to the V (AC) or V (DC) position.
3. Press the range button of the J 39200 in order to select the desired voltage range.
4. Press the MIN MAX button of the J 39200 . The J 39200 displays 100 ms RECORD and emits an audible tone (beep). IMPORTANT: The 100 ms RECORD mode is the length of time an input must stay at a new value in order to record the full change.
5. Simulate the condition that is potentially causing the intermittent connection, either by wiggling the connections or the wiring, test driving, or performing other operations. Refer to «Inducing Intermittent Fault Conditions»(ref-187796-S40174375812005090100000) .
6. Listen for the audible Min Max Alert which indicates that a new minimum or maximum value has been recorded.
7. Press the MIN MAX button once in order to display the MAX value and note the value.
8. Press the MIN MAX button again in order to display the MIN value and note the value.
9. Determine the difference between the MIN and MAX values. If the variation between the recorded MIN and MAX voltage values is 1 volt or greater an intermittent open or high resistance condition exists. Repair the condition as necessary. If the variation between the recorded MIN and MAX voltage values is less than 1 volt an intermittent open or high resistance condition does not exist.

Scan Tool Snapshot Procedure

Snapshot is a recording of what a control module on the vehicle was receiving for information while the snapshot is being made. A snapshot may be used to analyze the data during the time a vehicle condition is current. This allows you to concentrate on making the condition occur, rather than trying to view all the data in anticipation of the fault. The snapshot contains information around a trigger point that you have determined. Only a single data list may be recorded in each snapshot. The Scan Tool has the ability to store 2 snapshots. The ability to record 2 snapshots allows comparing hot versus cold and good versus bad vehicle scenarios. The snapshots are stored on a first-in, first-out basis. If a third snapshot is taken, the first snapshot stored in the memory will be lost.

Snapshots can be 1 of 2 types

1. Snapshot - taken from the Snapshot menu choice
2. Quick Snapshot - taken from the Data Display soft key choice, does not contain DTC information

When a snapshot is taken, it is recorded on the memory card and may contain as many as 1200 frames of information. Because the snapshot is recorded onto the memory card, snapshots are not lost if the Scan Tool is powered down.

The snapshot replay screen has a plot soft key that can be of great value for intermittent diagnosis. The snapshot plot feature can help you to quickly determine if a sensor is outside of its expected values by plotting 3 parameters at a time. The data will be displayed both graphically and numerically showing the minimum and maximum values for all frames captured. This is helpful, especially if the fault occurs only once and does not set a DTC.

Scheme 47

The fuse is the most common method of an automotive wiring circuit protection. Whenever there is an excessive amount of current flowing through a circuit the fusible element will melt and create an open or incomplete circuit. Fuses are an one time protection device and must be replaced each time the circuit is overloaded. To determine if a fuse is open, remove the suspected fuse and examine the element in the fuse for an open (2). If not broken (1), also check for continuity using a DMM or a continuity tester. If the element is open or continuity is suspect, replace the fuse with one of equal current rating.

Fuse Types