Chassis Electrical
GENERAL INFORMATIONThe chassis electrical system operates on a twelve Volt power supply with negative ground polarity. Each wire in the car is of a specific size and has an identifying colored insulation.
These colors are indicated in wiring diagrams and help in tracing circuits and making proper connections.
Wire size is determined by load capacity and circuit length. Some wires are grouped together and taped. Such a grouping of wires is called a harness. The main cable harness consists of the engine, transmission, body, Instrument, door, luggage, rear defogger, dome light and hatch gate cable harnesses.
The harness use a split corrugated tube to protect the wires from the elements. Each circuit consists of the following:
- Power source - the battery and the alternator.
- Wires - To carry electrical current through the circuit.
- Fuses - To protect the circuit against current overload.
- Relays - To protect voltage drop between the battery and the circuit parts and to protect the switch points against burning.
- Switches - To open and close the circuit.
- Load - Any device, such as a light or a motor, which converts the electrical current into useful work.
- Ground - To allow the current to flow back to the power source.
NOTES FOR WORKING ON ELECTRICAL ITEMS
Battery Cable
Disconnecting the Battery Cable
1. All switches should be in the "OFF" position.
2. Disconnect the battery ground cable.
3. Disconnect the battery positive cable.
CAUTION: It is important that the battery ground cable be disconnected first. Disconnecting the battery positive cable first can result in a short circuit.
Connecting The Battery Cable
Follow the disconnecting procedure in the reverse order.
CAUTION: Cable the battery terminal and apply a light coat of grease to prevent terminal corrosion.
Connector Handling
Disconnecting The Connectors
Some connectors have a tang lock to hold the connectors together during vehicle operation. Some tang locks are released by pulling them towards you (1).
Other tang locks are released by pressing them forward (2).
Determine which type of tang lock is on the connector being handled.
Firmly grasp both sides (male and female) of the connector.
Release the tang lock and carefully pull the two halves of the connector apart.
Never pull of the wires to separate the connectors. This will result in wine breakage.
- When removing the connector for relay (MR5B type), unfasten the tang lock of the connector by using a screwdriver and pull the relay out.
Connecting the Connector
Firmly grasp both sides (male and female) of the connector. Be sure that the connector pins and pin holes match. Be sure that both sides of the connector are aligned with each other.
Firmly but carefully push the two sides of the connector together until a distinct click is heard.
Connector Inspection
Use a circuit tester to check the connector for continuity. Insert the test probes from the connector wire side. (Refer to waterproof type connector inspection.) ZZZZZZZ
Never insert the circuit tester test probes into the connector open end to test the continuity. Broken or open connector terminals will result.
Waterproof Connector Inspection
It is not possible to insert the test probes into the connector wire side of a waterproof connector. Use one side of a connector (1) with its wires cut to make the test. Connect the test connector (2) to the connector to be tested. Connect the test probes to the nut wires to check the connector continuity.
Connector Pin Removal
Connector Housing Tang Lock Type
1. Insert a slender shaft into the connector housing open end.
2. Push the tang lock up (in the direction of the arrow in the illustration). Pull the wire with pin free from the wire side of the connector.
Pin Tang Lock Type
1. Insert a slender shaft into the connector housing open end.
2. Push the tang lock flat (toward the wire side of the connector). Pull the wire with pin free from the wire side of the connector.
Connector Pin Insertion
1. Check that the tang lock is fully up.
2. Insert the pin from the connector wire side. Push the pin in until the tang lock closes firmly.
3. Gently pull on the wires to make sure that the connector pin is firmly set in place.
Parts Handling
Be careful when handling electrical parts. They must not be dropped or thrown, otherwise short circuit or improper electrical operation may result.
Cable Harness
1. When assembling the parts, be careful not to pinch or wedge the wiring harness.
2. All electrical connections must be kept clean and tight.
3. Use a grommet or guard tube to protect the wiring harness from contacting a sharp edge or surface.
4. Position the wiring harness with enough clearance from the other parts and guard the wiring harness with a vinyl tube and clips to avoid direct contact.
5. The wiring harness between engine and chassis should be long enough to prevent chafing or damage due to vibration.
Splicing Wire
1. Open the Harness
If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores).
If the harness has a black plastic conduit, simply pull out the desired wire.
2. Cut the Wire
Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 11/2" (400 mm) away from other splices, harness branches, or connectors.
3. Strip the Insulation
When replacing a wire, use a wire of the same size as the original wire. Check the stripped wire for nicks or cut stands. If the wire is damaged, repeat the procedure on a new section of wire. The two stripped wire ends should be equal in length.
4. Crimp the Wires
Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the direction included with you clips. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the two stripped wire ends and hold them between your thumb and forefinger. Then center the splice clip under the stripped wires and hold it in place.
- Open the crimping tool to its full width and rest one handle on a firm flat surface.
- Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the back of the splice clip touches the wings of the clip.
- Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes.
Before crimping the ends of the clip, be sure that:
- The wires extend beyond the clip in each direction.
- No strands of wire are cut loose, and
- No insulation is caught under the clip. Crimp the splice again, one on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires.
5. Solder
Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the solder equipment manufacturer's instructions.
6. Tape the Splice
Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness.
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape.