Vehicle Damage Warnings
ELECTRICAL AND ELECTRONICElectronic components used in automotive computers are designed to operate at low voltages (3 - 5V) and are extremely susceptible to damage caused by static electrical discharge. Voltages as low as 12V 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.
There are several ways in which a person can become statically charged, the most common of which are friction and induction. 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, 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. Touch ground to discharge static electrical charges before handling electronic parts and maintain a bare skin ground connection (such as on the wrist) when servicing sensitive components.
USE OF PROPER TOOLS AND TESTING PROCEDURES
Unless use of an analog meter is specified by a testing procedure, use a digital volt/ohm meter (DVM) with a minimum 10 megohms internal impedance when testing an ECU or related components. Analog meters have low internal impedance and cause circuit "loading" in low voltage circuits, resulting in inaccurate measurements and possible damage to components.
Always follow recommended testing procedures. Never ground or apply voltage to a circuit unless specified by a testing procedure. The ECU provides a regulated constant low voltage to 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. Touch ground to discharge static electrical charges before handling electronic parts and maintain a bare skin ground connection (such as on the wrist) when servicing sensitive components.
2. Never touch ECU connector pins, integrated circuit connector pins or soldered components on ECU circuit boards.
3. Ensure that the battery is properly connected before attempting to start engine.
4. Do not disconnect the battery when the engine is running.
5. Fully release connector locks prior to parting connectors. 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 "ON" unless specifically directed to do so in a test procedure.
7. In order to disable the ignition system, unplug primary connections only. NEVER disconnect 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 circuit continuity.
10. When charging a battery, disconnect cables.
11. When replacing electronic components, disconnect 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 ECU harness connector, first disconnect harness connector. Then turn ignition "ON" as necessary.
13. To prevent deforming ECU harness connectors, do not probe terminals directly. Insert a pin from the harness side and perform measurements through pin.
14. Avoid getting water on fuel system and electronic engine control components.
15. Fuel and engine control system wiring should be at least 4 inches away from high tension cables.
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 boot only. Never pull directly on leads.
18. Always use 12V 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 ECU.
21. Never use a booster/starter which has a voltage rating above 12V to start engine.
22. Before performing electrical welding, disconnect battery, climate control, injection, cruise control, ECU and radio.
23. When temperatures may exceed 176°F (80°C), such as in an infra-red spray booth, remove all ECUs.
24. Batteries contain acid and produce explosive hydrogen gas. 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 problems as soon as possible.
d. Do not disconnect any spark plug wires with engine running.
e. Avoid push starting the vehicle.
f. If running on a dynamometer, make sure the catalytic converter is well ventilated.
g. To avoid of burns, use caution when working near the catalytic converter.
2. Do not use silicone based products on an oxygen sensor equipped vehicle. These products may contaminate the sensor.
3. When performing a compression test, remove the fuel pump relay or fuse and disconnect ignition system power. This will stop fuel flow to injectors and prevent engine starting.