Failure Code Determination

During any diagnostic procedure, "hard failure" codes MUST be distinguished from "intermittent failure" codes. Diagnostic charts CANNOT be used to analyze "intermittent failure" codes, except as noted under Diagnostic Procedure. To determine "hard failure" codes and "intermittent failure" codes, proceed as follows:

1. Enter diagnostics and note stored trouble codes. Clear trouble codes. Exit diagnostics. Turn ignition on, wait 5 seconds and start engine. Accelerate to 2000 RPM for a few seconds and return to idle speed.
2. Shift transmission into drive. Shift transmission into park. If "CHECK ENGINE" light comes on, enter diagnostics, read and record trouble codes. This will reveal "hard failure" codes. Cruise control codes "60-68" never set "CHECK ENGINE" light; treat them as "hard failures". Codes "13", "24", "25", "44" and "45" may require road test to reset "hard failure" after trouble codes were cleared.
3. If "CHECK ENGINE" light does not come on, all stored trouble codes were "intermittent failures", except as noted under Diagnostic Procedure.
   PROGRAMMED ECM TROUBLE CODES
   
   

   Code	Circuit Affected
   12	No tach signal.
   13	Oxygen sensor not ready.
   14	Shorted coolant sensor circuit.
   15	Open coolant sensor circuit.
   16	Generator output voltage out of range.
   17	Crank signal circuit high.
   18	Open crank signal circuit.
   19	Fuel pump circuit high.
   20	Open fuel pump circuit.
   21	Shorted TPS circuit.
   22	Open TPS circuit.
   23	EST/By-pass circuit shorted or open.
   24	Speed sensor failure.
   25	Modulated displacement failure.
   26	Shorted throttle switch circuit.
   27	Open throttle switch circuit.
   30	ISC circuit.
   31	Shorted MAP sensor circuit.
   32	Open MAP sensor circuit.
   33	MAP/BARO sensor correlation.
   34	MAP sensor circuit.
   35	Shorted BARO sensor circuit.
   36	Open BARO sensor circuit.
   37	Shorted MAT sensor circuit.
   38	Open MAT sensor circuit.
   44	Oxygen sensor lean.
   45	Oxygen sensor rich.
   51	PROM insertion faulty.
   60	Drive (ADL) switch faulty.
   61 & 68	Set and resume switch circuit.
   62	Car speed exceeds maximum limit.
   63	Car and set speed tolerance exceeded.
   64	Car acceleration exceeds maximum limit.
   65	Coolant temperature exceeds maximum limit.
   66	Engine RPM exceeds maximum limit.
   70	System ready - Switch tests.
   71	Brake light switch.
   72	ISC throttle switch.
   73	Drive (ADL) switch.
   74	Back-up light switch.
   75	Cruise on/off circuit.
   76	Set/coast circuit.
   77	Resume/acceleration circuit.
   78	Instant/average MPG button.
   79	Reset MPG button.
   80	A/C clutch circuit. 88 Display check.
   90	System ready to display engine data.
   95	System ready for actuator cycling.
   96	Actuator cycling.
   97	MD cylinder solenoid cycling.
   00	All diagnostics complete.