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HOMESERVICE MANUALSCHEVROLET1992CHEVY VAN G20, 5.7 KREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - V6TROUBLE CODE CHARTSCODE 42, ELECTRONIC SPARK TIMING (EST)NOTES
1992 Chevrolet Chevy Van G20, 5.7 K

Code 42, Electronic Spark Timing (Est): Notes

1992 Chevrolet Chevy Van G20, 5.7 KSECTION Notes

Code 42 indicates ECM has seen an open or short to ground in HEI EST or by-pass circuits.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This test confirms Code 42 and determines if fault is a hard failure or intermittent condition.
  2. This tests for a normal EST ground path through the ignition module. If circuit No. 423 is shorted to ground, reading will be less than 500 ohms.
  3. As test light voltage touches circuit No. 424, the module should switch. This causes ohmmeter to "over-range" with meter in 100-200 ohm range. A higher ohm range will indicate over 5000 ohms. This test assures the module switched.
  4. If module did not switch, this step tests for a short in circuit No. 423, an open in circuit No. 424 and a faulty ignition module connection or module.
  5. This step confirms Code 42 is a faulty ECM and not an intermittent problem in circuits No. 423 and 424.
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