Diagnostic Tools

The CCC system does not require special tools for diagnosis. A tachometer, a dwell meter, test light, ohmmeter, digital voltmeter with 10 megohms impedance (minimum), vacuum pump, vacuum gauge and 6 jumper wires 6" long (1 wire with female connectors at both ends; 1 wire with male connector at both ends; 4 wires with male and female connectors at opposite ends) are the only tools necessary for diagnosis.

NOTE: Special testers can be used to read trouble codes and check voltages in the system. These tools can save a great deal of time, but are not required. Refer to tester manual for operating procedures.

A test light, rather than a voltmeter, must be used when indicated by a diagnostic chart.

NOTE: If engine operation seems to change when the dwell meter is connected to Green wire, remove dwell meter and use another type. A few brands are not compatible with CCC system.

The diagnostic circuit check is an organized approach for identifying a problem caused by the fuel injection system. Driver complaints fall into 3 categories: Steady "CHECK ENGINE" light, driveability problems and "engine cranks, but will not run". Understanding the chart and using it correctly will reduce diagnostic time and prevent unnecessary replacement of parts.

1) A steady "CHECK ENGINE" light with ignition on and engine not running confirms battery and ignition voltage to Electronic Control Module (ECM).
2) Ground diagnostic test terminal by connecting a jumper wire between terminals "A" and "B" in ALDL connector located below instrument panel. The ECM will cause "CHECK ENGINE" light to flash Code 12, indicating that ECM diagnostics are working. Code 12 will flash 3 times, followed by other trouble codes stored in memory. If there are no other codes, Code 12 will flash until diagnostic test terminal is disconnected or engine is started.
3) Record all stored codes, except Code 12. If the problem is "engine cranks but will not run", go to CHART A3.
4) If no other codes were recorded, perform "Field Service Mode" check. With engine running and diagnostic terminal grounded, the ECM will respond to the oxygen sensor signal and use the "CHECK ENGINE" light to display the following information:
A) Closed loop confirms that oxygen sensor signal is being used by the ECM to control fuel delivery and that system is working properly. Signal voltage will vary from less than .35 to more than .55 volts.
B) Open loop indicates that oxygen sensor signal is not usable to ECM. Signal voltage will be constant and between .35 and .55 volts. System will flash "open loop" for 30 seconds to 2 minutes after engine starts or until sensor reaches normal operating temperature. If system fails to go into closed loop, see Code 13.
C) "CHECK ENGINE" light out indicates that exhaust is lean. Oxygen sensor signal voltage will be less than .35 volts and steady. See Code 44.
D) "CHECK ENGINE" light on steady indicates that exhaust is rich. Oxygen sensor signal voltage will be greater than .55 volts and steady. See Code 45.
5) Road test of the system in the field service mode should be done only at steady road speeds. The following conditions may be observed and should be considered normal: Light may be "ON" too long under acceleration, light may be "OFF" too long under deceleration, light may be "ON" too long with idle below 1200 RPM.

Fig 1: Diagnostic Circuit Check

Fig 2: Diagnostic Circuit Check