Key On Engine Running Test & Code Descriptions

ENGINE RUNNING FUNCTIONAL TEST
1. Make sure that engine is at normal operating temperature. Run engine at 2000 rpm for 2 minutes, then turn key off. Immediately restart engine and allow to idle.
2. Observe voltmeter and vacuum gauge for initialization pulses after restarting the engine. The throttle kicker will also extend (increase engine speed) and remain on throughout the test.
3. On vehicles with spark knock sensor, when initial pulses occur, immediately simulate spark knock by placing a 3/8 inch extension on manifold near base of knock sensor. Tap end of extension with a small hammer for about 15 seconds.
4. On vehicles without spark knock sensor, observe voltmeter for 4 one second initialization pulses after restarting the engine. After the 4 initial pulses appear, observe and record voltmeter pulses (service codes). Within 90 seconds, the service codes are complete and the throttle kicker will retract (decrease engine speed).
5. Observe results and record codes, then continue to the appropriate tests under Subroutines as indicated below:

NOTE: Code 11--On vehicles which exhibit detonation under wide open throttle and/or poor performance, and are equipped with universal ignition modules, continue to Spark Knock, Only At Wide Open Throttle And/Or Poor Performance/Mileage test under Functional Test. On all other models, MCU unit is okay.

No Start Condition - Continue to Test 1 No Start, Detects MCU Faults Only.

No Initialization Pulses on Voltmeter or Erroneous Codes - Continue to Test 16 No Self-Test Output.

No Pulses on Vacuum Gauge - Continue to Test 16, No Self-Test Output.

No Throttle Kicker Extension or RPM Increase - Continue to Test 8, RPM Out Of Specifications.

Code 12 - Continue to Test 11, Idle Speed Incorrect.

Code 25 - Continue to Test 15, Knock Detection System Inoperative.

Code 41 - Continue to Test 5, EGO Always Lean.

Code 42 - Continue to Test 10, EGO Always Rich.

Code 44 - Continue to Test 12, Thermactor Check.

Code 45 - Continue to Test 13, Thermactor Check.

Code 46 - Continue to Test 14, Thermactor Air Bypass Check, Always Not Bypassing.

Code 53 or 54 - Continue to Test 2, Open Temperature Switch.

Code 51 or 55 - Continue to Test 3, Vacuum Switch Open.

Code 65 - Continue to Test 4, Vacuum Switch Closed.