Circuit Testing Procedures - Non-Dtc-Based Diagnostics: Diagnosis RAM Pickup 2500

TROUBLESHOOTING TOOLS

When diagnosing a problem in an electrical circuit there are several common tools necessary. These tools are listed and explained below.

1. Jumper Wire - This is a test wire used to connect two points of a circuit. It can be used to bypass an open in a circuit.

1. Voltmeter - Used to check for voltage on a circuit. Always connect the black lead to a known good ground and the red lead to the positive side of the circuit.

1. Ohmmeter - Used to check the resistance between two points of a circuit. Low or no resistance in a circuit means good continuity.

Scheme 23

1. Probing Tools - These tools are used for probing terminals in connectors. Select the proper size tool from Special Tool Package (special tool #6807, Terminal Tools), and insert the probing end (2) into the terminal being tested. Use the other end of the tool (1) to insert the meter probe.

TROUBLESHOOTING WIRING PROBLEMS

When troubleshooting wiring problems there are six steps which can aid in the procedure. The steps are listed and explained below. Always check for non-factory items added to the vehicle before doing any diagnosis. If the vehicle is equipped with these items, disconnect them to verify these add-on items are not the cause of the problem.

1. Verify the problem.
2. Verify any related symptoms. Do this by performing operational checks on components that are in the same circuit. Refer to the appropriate wiring diagram information.
3. Analyze the symptoms. Use the wiring diagrams to determine what the circuit is doing, where the problem most likely is occurring and where the diagnosis will continue.
4. Isolate the problem area.
5. Repair the problem area.
6. Verify the proper operation. For this step, check for proper operation of all items on the repaired circuit. Refer to the appropriate wiring diagram information.

Diagnostic Test

1. Turn the ignition off. Disconnect the wire harness connector of the component that is receiving the voltage. NOTE: Check connectors - Clean/repair as necessary. At this time, leave all in-line connectors connected. NOTE: Before inspecting any circuits, first test the 12-volt test light. Connect the 12-volt test light to battery ground or to any other known good ground. Touch the lead of the test light to Battery +. If the test light is good, it should illuminate brightly. Connect the 12-volt test light to a known good ground. Use the test light lead to carefully probe the Battery or Ignition Voltage circuit in the harness connector. First check with the ignition off, next check with the ignition on, and lastly check while cranking the engine. Does the test light illuminate brightly? Yes The circuit is not open at this time or the condition that originally caused the open may not be present at this time. Continue to monitor the test light and wiggle the wire harness and connectors to check for an intermittent open or excessive resistance condition. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the open could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply. No Repair the open in the circuit. Use the wiring application as a guide to trace the circuit and look for any in-line connectors where the short could occur. One way to help isolate the open is to disconnect any in-line connectors and measure the resistance from one side of the in-line connector to the matching component harness connector. If the open goes away, the open is on the other side of the in-line connector. If this is a fused circuit, make sure to inspect the fuse. If the fuse is open, check the circuit for a short to ground before installing a new fuse. The circuit may have a short to ground causing the fuse to open. This short to ground could be in the wire harness or in one of the components the circuit is supplying voltage to.

1. Turn the ignition off. Disconnect the wire harness connectors of the components that contain the circuit suspected as being shorted to ground. NOTE: Check connectors - Clean/repair as necessary. NOTE: Before checking the circuit for a short to ground, first measure the resistance between the two leads of the multimeter. Take this value and subtract it from the value recorded when measuring the resistance between ground and the circuit being checked. The leads of the meter can add up to or over 0.5 of an Ohm of resistance. With the component wire harness connectors disconnected, use a meter set to measure Ohms (↑©), and measure the resistance between the circuit and a known good ground. Use the negative lead of the meter and touch a known good ground. Use the positive lead of the meter and carefully probe the circuit suspected as having the short. Is the resistance to ground below 10k Ohms ? Yes Repair the short to ground. Use the wiring application as a guide to follow the path of the circuit. One way to help isolate the short is to disconnect any in-line connectors that the circuit being tested runs through and measure for the short again. If the short goes away, the short is on the other side of the in-line connector. No The circuit is not shorted to ground or the condition that originally caused the short may not be present at this time. Continue to measure the resistance, wiggle the wire harness and connectors while checking for an intermittent short. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.

Scheme 24

The purpose for the following procedure is to show different methods of checking the voltage of a circuit. When diagnosing a DTCs it might be necessary to verify that proper voltage is on a circuit or that a circuit is not shorted high. Below are four examples of checking the voltage in a circuit.

Scheme 25

Scheme 26

Scheme 27

1. CHECKING FOR VOLTAGE NOTE: The connector displayed in the graphics are only an example. Turn the ignition off. Disconnect the wire harness connector of the component that is being tested. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. Use a multimeter set to measure DC voltage. Connect the ground lead of the meter to a known good ground circuit. Use the positive lead of the multimeter and probe the circuit you are checking for voltage. Ignition on, engine not running. Is the voltage within specifications for this circuit? Yes The circuit is functioning properly or the condition that originally caused the open or short may not be present at this time. Continue to measure the voltage and wiggle the wire harness and connectors while checking for an intermittent open or short. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins that may apply. No Repair the open or short to ground in the circuit. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur. One way to help isolate the open or short is to disconnect any in-line connectors that the circuit being checked runs through and check for the voltage again. If the voltage is present, the open or short is on the other side of the in-line connector.
2. CHECKING FOR A SHORT TO BATTERY VOLTAGE USING A MULTIMETER Turn the ignition off. Disconnect the wire harness connectors of the components that contain the circuit that is suspected as having a short. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. With all the component wire harness connectors disconnected, use a multimeter set to measure DC voltage. Connect the ground lead of the meter to a known good ground circuit. Use the positive lead of the multimeter and probe the circuit you suspect has a short. Is there any voltage present? Yes Repair the short to battery voltage. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur. One way to help isolate the short is to disconnect any in-line connectors that the circuit being checked runs through and measure for the short again. If the short goes away, the short is on the other side of the in-line connector. No The circuit is not shorted to voltage or the condition that originally caused the short may not be present at this time. Continue to measure the voltage and wiggle the wire harness to check for an intermittent short. NOTE: By disconnecting the wire harness connectors you may have eliminated the source of the voltage causing the short. Use the wiring application as a guide, check to see if there are any battery circuits in the same wire harness as the circuit you are testing. It is necessary to check for a short to those circuits using an Ohm meter and perform the Check for a Short Between Multiple Circuits diagnostic procedure. Refer to «Standard Procedure»(ref-457933-S09059618372012030200000) . Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.
3. CHECKING FOR A SHORT TO IGNITION VOLTAGE OR TO CHECK FOR VOLTAGE ON A CIRCUIT USING A MULTIMETER Turn the ignition off. Disconnect the wire harness connectors of all components that contain the circuits that are suspected as being shorted. At this time leave all in-line connectors connected. With all the component wire harness connectors disconnected, use a multimeter set to measure DC voltage. Connect the ground lead of the meter to a known good ground circuit. Use the positive lead of the multimeter and probe the circuit you suspect has a short. Ignition on, engine not running. Is any voltage present? Yes Repair the short to ignition voltage. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur. One way to help isolate the short is to disconnect any in-line connectors that the circuit being checked runs through and check for the short again. If the short goes away, the short is on the other side of the in-line connector. No The circuit is not shorted to voltage or the condition that originally caused the short may not be present at this time. Continue to measure the voltage and wiggle the wire harness to check for an intermittent short. NOTE: By disconnecting the wire harness connectors you may have eliminated the source of the voltage causing the short. Use the wiring application as a guide, check to see if there are any battery circuits in the same wire harness as the circuit you are testing. It is necessary to check for a short to those circuits using an Ohm meter and perform the Check for a Short Between Multiple Circuits diagnostic procedure. Refer to «Standard Procedure»(ref-457933-S09059618372012030200000) . Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.
4. CHECKING FOR A SHORT TO VOLTAGE USING A 12-VOLT TEST LIGHT Turn the ignition off. Disconnect the wire harness connectors of all components that contain the circuits that are suspected as being shorted. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. NOTE: Before inspecting any circuits, first test the 12-volt test light. Connect the 12-volt test light to battery ground or to any other known good ground. Touch the lead of the test light to Battery +. If the test light is good, it should illuminate brightly. Connect the 12-volt test light to a known good ground circuit. Use the lead of the test light and carefully probe the circuit you suspect has a short. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury. First, check with the ignition off , next with the ignition on, and lastly while cranking the engine. Does the test light illuminate brightly? Yes Repair the short to voltage. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur. One way to help isolate the short is to disconnect any in-line connectors that the circuit being checked runs through and check for the short again. If the short goes away, the short is on the other side of the in-line connector. No The circuit is not shorted to voltage or the condition that originally caused the short may not be present at this time. Continue to measure the resistance and wiggle the wire harness to check for an intermittent short. NOTE: By disconnecting the wire harness connectors you may have eliminated the source of the voltage causing the short. Use the wiring application as a guide, check to see if there are any battery circuits in the same wire harness as the circuit you are testing. It is necessary to check for a short to those circuits using an Ohm meter and perform the Check for a Short Between Multiple Circuits diagnostic procedure. Refer to «Standard Procedure»(ref-457933-S09059618372012030200000) . Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related component and wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.

1. Turn the ignition off. Disconnect the wire harness connectors of the components that contain the ground circuit suspected as containing excessive resistance. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. NOTE: Before inspecting any circuits, first test the 12-volt test light. Connect the 12-volt test light to battery ground or to any other known good ground. Touch the lead of the test light to Battery +. If the test light is good, it should illuminate brightly. With all the component wire harness connectors disconnected, connect the 12-volt test light to Battery +. Use the test light lead to lightly probe the ground circuit in the harness connector. Does the test light illuminate brightly? Yes The suspected ground circuit is not open or the condition that originally caused the open or excessive resistance is not present at this time. Another way to check for an open would be to use an Ohm meter and measure the resistance of the ground circuit. While continuing to measure the resistance of the circuit, wiggle the wire harness and connectors to check for an intermittent open or poor connection. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the open could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply. No Repair the open in the circuit between the two wire harness connectors. Use the wiring application as a guide to trace the circuit and look for any in-line connectors where the short could occur. One way to help isolate the open is to disconnect any in-line connectors and measure the resistance from one side of the in-line connector to the matching component harness connector. If the open goes away, the open is on the other side of the in-line connector.

1. Turn the ignition off. Disconnect the wire harness connectors of the components that contain the circuits that are suspected as being shorted together. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. NOTE: Before you measure the resistance between any circuits, first measure the resistance between the two leads of the multimeter. Take this value and subtract it from the value recorded after measuring the resistance between the circuits. The leads of the meter can add up to or over 0.5 of an Ohm of resistance. With all the component wire harness connectors disconnected, use a multimeter set to Ohms (↑©), and measure the resistance between the applicable circuits in one of the harness connectors. Use one lead of the multimeter and carefully probe the circuit suspected as being shorted. Use the other lead of the meter and one at a time, carefully probe the other circuits in the harness connector. Is the resistance below 10k Ohms when probing any two circuits? Yes Repair the short between the circuits. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur. One way to help isolate the short is to disconnect any in-line connectors that the circuit being tested runs through and measure for the short again. If the short goes away, the short is on the other side of the in-line connector. No The circuit is not shorted or the condition that originally caused the short may not be present at this time. Continue to measure the resistance and wiggle the wire harness and connectors while checking for an intermittent short. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.

1. Turn the ignition off. Disconnect the Negative Battery cable (ground). Using a multimeter, set the multimeter leads up to properly measure Amperage. Connect the ground lead that is plugged into the COM port of the multimeter to the Negative Battery cable. Connect the other lead of the multimeter that is plugged into the Amp port of the multimeter to the negative battery post/terminal. CAUTION: Do not crank the engine or turn on any accessories that may draw more than 10 Amps. You may open the protective fuse in the multimeter. NOTE: To get a more accurate reading and current draw, wait 20 minutes to make sure all modules have powered down before continuing. Some modules may stay powered up longer than others. While monitoring the amperage reading, remove a fuse and see if the amperage drops. If the amperage does not drop, install that fuse you just removed and remove the next fuse. Does the amperage drop to between 0.02 to 0.04 of an Amp when removing any fuses. Yes Use the wiring application as a guide to find out what components or modules are powered by the fuse. At this point you can install the fuse and begin disconnecting the components powered by the fuse. When the amperage drops after disconnecting a component you will know which component is at fault. It is important to know how long some modules are supposed to remain awake. You don't want to replace a component that is operating normally. No The condition that originally caused the draw may not be present at this time. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded ground terminals. Perform any Technical Service Bulletins that may apply.

1. Turn the ignition off. Disconnect the wire harness connectors of the components that contain the circuit suspected as being open. NOTE: Check connectors - Clean/repair as necessary. At this time leave all in-line connectors connected. NOTE: Before measuring the resistance of any circuit, first measure the resistance between the two leads of the multimeter. Take this value and subtract it from the value recorded when measuring the resistance of the circuit being checked. The leads of the meter can add up to or over 0.5 of an Ohm of resistance. With the component wire harness connectors disconnected, use a multimeter set to Ohms (↑©), and measure the resistance of the circuit. Use one lead of the meter and probe the circuit in one harness connector. Use the other lead of the meter and probe the same circuit in the other harness connector. Is the resistance in the circuit below 20k Ohms? Yes Repair the excessive resistance in the circuit between the two wire harness connectors. Using the wiring application as a guide, trace the circuit and check for any in-line connectors where the open or excessive resistance could occur. One way to help isolate the open is to disconnect any in-line connectors and measure the resistance from one side of the in-line connector to the matching component harness connector. If the open or excessive resistance is not present, the open or excessive resistance is on the other side of the in-line connector No The circuit does not contain any excessive resistance or the condition that originally caused the excessive resistance may not be present at this time. Continue to measure the resistance of the circuit, wiggle the wire harness and connectors to check for an intermittent open or poor connection. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the open could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.

Scheme 28

Scheme 29

1. MEASURE THE VOLTAGE BETWEEN THE 5-VOLT SUPPLY CIRCUIT AND GROUND Turn the ignition off. Disconnect the sensor harness connector. NOTE: Check connectors - Clean/repair as necessary. Turn the ignition on. Use a multimeter set to measure DC voltage. Connect the negative lead of the meter to a known good ground. With the positive lead of the meter, carefully probe the 5-volt supply circuit. Is the voltage between 4.7 and 5.2 volts? Yes Go To 2 . No Check the 5-volt supply circuit for an open or short to ground. Perform the appropriate Sensor Reference Voltage DTC diagnostic procedure for assistance, if one exists.
2. MEASURE THE VOLTAGE BETWEEN THE 5-VOLT SUPPLY AND SENSOR GROUND CIRCUIT The multimeter is still set to measure DC voltage. Move the negative lead of the meter to carefully probe the sensor ground or sensor return circuit in the harness connector. With the positive lead of the meter, carefully probe the 5-volt supply circuit. Is the voltage between 4.8 and 5.2 volts? Yes At this time the 5-volt supply and sensor ground circuit are working properly. Continue to measure the voltage between the wires, wiggle the wire harness and connectors while checking for an intermittent condition. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the short could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply. No Repair the open or excessive resistance in the Sensor Ground (Sensor Return) circuit.

Scheme 30

All ESD sensitive components are solid state and a symbol is used to indicate this. When handling any component with this symbol, comply with the following procedures to reduce the possibility of electrostatic charge build up on the body and inadvertent discharge into the component. If it is not known whether the part is ESD sensitive, assume that it is.

1. Always touch a known good ground before handling the part. This should be repeated while handling the part and more frequently after sliding across a seat, sitting down from a standing position, or walking a distance.
2. Avoid touching electrical terminals of the part, unless instructed to do so by a written procedure.
3. When using a voltmeter, be sure to connect the ground lead first.
4. Do not remove the part from it's protective packing until it is time to install the part.
5. Before removing the part from it's package, ground the package to a known good ground on the vehicle.

1. Turn the ignition off. Use the wiring application as a guide, trace the circuit being tested and locate the components related to the circuit. Set your multimeter up to check for DC voltage. Carefully back probe the two component harness connectors of the circuit being tested. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury. NOTE: If you are testing the starting circuit, disable the engine so the engine does not start. Crank the engine for five seconds if you are testing the starting circuit and monitor the multimeter voltage reading. For circuits that don't require the engine running, turn the ignition on. For circuits that require the engine running, start the engine. NOTE: If the circuit you are checking needs to be turned on, such as Blower Motor or a lamp, do so now. Monitor the voltage reading. The voltmeter will show the difference in voltage between the two points. Is the voltage less than 0.4 of a Volt? Yes At this time the circuit is functioning properly. Continue to measure the voltage between the components and wiggle the wire harness and connectors while checking for an intermittent condition. Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the excessive resistance could occur intermittently. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply. No Repair the excessive resistance in the circuit. Use the wiring application as a guide to trace the circuit and look for any in-line connectors where the excessive resistance may occur. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors. Perform any Technical Service Bulletins (TSBs) that may apply.