TESTING THE DDEC II SYSTEM
A. TOOLS NEEDED TO DIAGNOSE THE SYSTEM
The following tools and equipment are required to properly diagnose a complete system:
l Voltmeter and Ohmmeter: Use a digital volt-ohmmeter J-34029 or equivalent to measure voltage and resistance where
required. A digital volt-meter must be used when specified in a procedure.
l Test Light 6V: Must be used when specified in the procedure.
l Jumper Wires: To bypass a circuit and to insert between special connectors. This will permit access to the connector
terminals for circuit checking.
l Diagnostic Data Reader (DDR): PRO-LINK 9000 J 38500-203
In addition, the tools listed below can be of aid in properly identifying problems, but are not required for this Troubleshooting
Tachometer: Either a crankshaft harmonic balance revolution pickup type or electronic coil trigger signal pickup type
tachometer can be used for diagnosis.
Pressure Gauge: To monitor turbo boost pressure (for purposes of comparison with the DDEC II Turbo Boost Sensor).
READING THE DIAGNOSTIC CODES
NOTE: If you have turned here to begin diagnosis of a problem and already know how to read codes, as well
as understand active and historical codes, turn to the first chart (Iabelled START) on page 17.
1. Active vs. Historical Codes:
DDEC II makes use of both types of codes As their names imply, the difference between the two are as follows:
Active Codes - These are the codes which are currently keeping the Check Engine light on. They can only
be read using the Diagnostic Data Reader.
Historical Codes - These are all the codes logged in the ECM (whether or not they are currently turning on the
Check Engine light). These codes can be cleared by using the Diagnostic Data Reader.
Codes 22, 43-45 and 85 will show additional information. Refer to Code 85 for a discussion of this.