Code 42 - Est Circuit Open Or Grounded: Notes
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Code 42 indicates ECM has seen an open or short to ground in HEI EST or by-pass circuit.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- This test confirms Code 42 and determines if fault is a hard failure or intermittent condition.
- This test checks for a normal EST ground path through ignition module. If EST circuit is shorted to ground, reading will be less than 500 ohms.
- As test light voltage touches by-pass circuit, module should switch. This will cause ohmmeter to switch from hundreds of ohms to thousands of ohms. This test assures module "switched".
- If module did not switch, this tests for a short in EST circuit, an open in by-pass circuit and a faulty ignition module connection or module.
- This step confirms Code 42 is a faulty ECM and not an intermittent problem in EST or by-pass circuits.