Ignition Systems With C-4 Emissions: Testing

NOTE: For further information on testing, see articles in this section on DELCO-REMY HIGH ENERGY IGNITION and articles on specific ignition systems.

To determine why "CHECK ENGINE" light is on, ground test lead under dash (black/white wire with green connector, attached to electronic control module - not HEI module). The following is a list of trouble codes and their identifications:

Code	Problem Area
12	No tach or reference signal to ECM.
13	Oxygen sensor circuit.
13 & 14	At same time, refer to code 43
14	Shorted coolant sensor circuit.
15	Open coolant sensor circuit.
21	Shorted wide open throttle circuit (if used). Throttle position sensor circuit.
22	Grounded closed throttle or wide open throttle switch circuit.
21 & 22	At same time, grounded wide open throttle circuit switch.
23	Open or grounded carburetor solenoid circuit.
32	Barometric pressure sensor output low.
32 & 55	At same time, grounded +8V, V (REF) or faulty ECM.
34	Manifold absolute pressure sensor output high.
43	Throttle position sensor adjustment.
44	Lean oxygen sensor.
45	Rich oxygen sensor.
44 & 45	At same time, faulty oxygen sensor or open sensor.
51	Faulty calibration (PROM) unit or improper PROM installation.
52 & 53	"CHECK ENGINE" light off - intermittent ECM problem, "CHECK ENGINE" light on - faulty ECM.
54	Faulty carburetor solenoid and/or ECM.
55	Faulty oxygen sensor, open manifold absolute, pressure sensor or ECM (3.8L V6), faulty ECM or throttle position sensor (exc. 3.8L V6).