ELECTROSTATIC DISCHARGE DAMAGE TO ECM (INFO.TO PREVENT)

ELECTROSTATIC DISCHARGE DAMAGE Revised to includes guidelines when servicing the electronic components

VEHICLES AFFECTED ALL 1981-1989 PASSENGER AND LIGHT ----------------- DUTY TRUCK SERIES WITH AN ELECTRONIC CONTROL MODULE (ECM)

This bulletin is being revised to include a listing of the electronic components which are sensitive to Electrostatic Discharge and may sustain damage as a result of electrostatic discharge. This listing has been included at the end of the bulletin.

Please add the following information to 6E Section "A" Diagnostic Charts/Trouble Codes, and to Section "C1" Electronic Control Module and Sensors.

NOTICE: To prevent possible Electrostatic Discharge damage:

- Do Not touch the ECM connector pins or soldered components on the ECM circuit board. - When handling a PROM, CAL-PAK or Mem-Cal, Do Not touch the component leads, and Do Not remove integrated circuit from carrier. - Be sure to follow the guidelines listed below if servicing any of these electronic components.

1. Do Not open the replacement part package until it is time to install the part. 2. Avoid touching electrical terminals of the part. 3. Before removing the part from its package, ground the package to a known good ground on the vehicle. 4. Always touch a known good ground before handling the part. This step should be repeated before installing the part if the part has been handled while sliding across the seat, while sitting down from a standing position, or while walking a distance.

Electronic components used in control systems are often designed to carry very low voltage, and are very susceptible to damage caused by electrostatic discharge. It is possible for less than 100 volts of static electricity to cause damage to some electronic components. By comparison, it takes as much as 4,000 volts for a person to even feel the zap of a static discharge.

There are several ways for a person to become statically charged. The most common methods of charging are by friction and by induction. An example of charging by friction is a person sliding across a car seat, in which a charge of as much as 25,000 volts can build up. Charging by induction occurs when a person with well insulated shoes stands near a highly charged object and momentarily touches ground. Charges of the same polarity are drained off, leaving the person highly charged with the opposite polarity. Static charges of either type can cause damage, therefore, it is important to use care when handling and testing electronic components.

* The following is a list of the electronic components which are sensitive to Electrostatic Discharge and may sustain damage as a result of electrostatic discharge:

- chime module - cruise control module - driver information system - automatic door lock module - central power supply - electronic level control module - theft deterrent module - automatic day/night mirror - cellular mobile telephone transceiver - radio/radio control - anti-lock brake system controller - engine control module - body control module - lamp monitor module - electronic (digital) clusters - electronic climate control and programmer - transaxle position decoder module - twilight sentinel amplifier - electronic spark timing module - supplemental inflatable restraint control module - visual information center - steering wheel remote control module - C31 ignition module

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.