Vehicle Damage Warnings
ELECTRICAL AND ELECTRONIC
Electronic components used in automotive computers are designed to operate at very low voltages (3-5V), and are extremely susceptible to damage caused by static electrical discharge. Voltages as low as 12 volts can damage computer circuits. By comparison, it takes as much as 4,000 volts of static discharge for a person to even feel the "ZAP", and there is no way of knowing whether the charge is positive or negative in nature.
There are several ways in which a person can become statically charged. Charging by friction and charging by induction are the most common. Friction between organic materials (such as cotton or leather) and synthetics (such as plastic, vinyl, or glass) will generate static charges as great as 25,000 volts. This can happen by simply sliding across a car seat or by wearing a cotton shirt under a coat made of synthetic materials. Charging by induction occurs when a person standing near a highly charged object (strong magnetic field such as a transformer) momentarily touches ground. Like charges are displaced to ground, leaving the person highly charged with opposite polarity. Static charges are gradually equalized by moisture in the air, but are retained much longer when humidity is low. Use care when handling and testing electronic components.
USE OF PROPER TOOLS AND TESTING PROCEDURES
Use a digital volt/ohm meter (DVOM) with a minimum 10 mega-ohms internal impedance when testing an ECU or related components, unless use of an analog meter is specified by a testing procedure. Analog meters have low internal impedance and cause circuit "loading" in low voltage circuits, resulting in inaccurate measurements and possible damage to components. Use of a DVOM is necessary to obtain accurate measurements and avoid damaging low voltage ECU circuits and components.
Always follow recommended testing procedures. Never ground or apply voltage to a circuit unless specified by a testing procedure. ECU's provide a regulated constant low voltage source to some circuits, which may require a minimum resistance (impedance) to operate. Directly grounding or applying battery power to these circuits could damage the ECU and cause a system failure.
NOTE: To avoid possible damage to electronic components, observe the following precautions:
1. Discharge any static electrical charges, before handling sensitive parts, by touching ground or maintaining a ground connection to a bare skin area like the wrist, when servicing sensitive parts.
2. Never touch the ECU connector pins, integrated circuit connector pins, or soldered components on the ECU circuit board.
3. Always ensure the battery is properly connected to the vehicle prior to attempting to start engine.
4. Don't disconnect the battery when the engine is running.
5. Fully release connector locks prior to disconnecting, ensure connectors are fully seated and all insulators and shields are in place when reinstalling.
6. Never connect or disconnect electrical connections with the ignition switch in the "ON" position unless specifically directed to do so in a test procedure.
7. In order to disable the ignition system, unplug the primary connections or ground ignition wire(s) to cancel desired cylinder(s). NEVER disconnect the secondary leads to disable the ignition system.
8. Do not use a self powered test lamp to check continuity.
9. Do not create any arcing to check the continuity of a circuit.
10. When charging a battery, be sure battery cables are disconnected.
11. When replacing electronic components, disconnect the battery ground.
NOTE: Before removing battery ground, access trouble codes. ECU memory will be erased if ground cable is removed.
12. When measuring voltage at the control unit harness connector, disconnect harness connector first, then turn ignition "ON" as necessary.
13. To prevent deforming control unit harness connectors, do not probe terminals directly. Instead, insert a pin from the harness side and perform measurements through pin.
14. Avoid getting water on any of the Fuel and Engine Control System Components.
15. Fuel and Engine Control System wiring should be at least 4 inches away from ignition wires.
16. Never pierce ignition leads or insulator boots to connect timing lights or analyzers. Use proper adapters.
17. When removing a spark plug wire twist the boot one quarter turn and pull on the boot only, never the lead itself.
18. Always use 12-volt batteries as a power source.
19. Never apply battery power to a component unless directed to do so in a test procedure.
20. Do not try to disassemble the control unit.
21. Never use a booster/starter which has a voltage rating above 12 volts to start engine.
22. Before performing electrical welding (for instance, spot welding), disconnect the battery, climate control, injection, cruise control, ECU and radio.
23. In cases when temperatures may exceed 176°F (80°C), (example: infra-red spray booth), remove all ECUs.
24. The battery contains acid and produces explosive gas (hydrogen), avoid creating sparks near battery.
ENGINE AND EXHAUST
1. On vehicles equipped with catalytic converters, the following conditions must be observed:
a. Use only "UNLEADED FUEL".
b. Avoid running out of fuel.
c. In case of poor engine operation (misfiring), avoid driving the vehicle and correct the problem as soon as possible.
d. Do not disconnect any spark plug wires with the engine running.
e. Avoid push starting the vehicle.
f. If running on a dynamometer, make sure the catalytic converter is well ventilated.
g. Use caution when working near the catalytic converter to prevent the possibility of burns.
2. Do not use silicone based products on an oxygen sensor equipped vehicle to avoid damaging the sensor.
3. When performing a compression test, remove the fuel pump relay fuse, and disconnect power to the ignition (This will stop fuel flow to the injectors and prevent engine from starting).