Electronic Spark Timing (All Engines)

An open or short to ground in the Electronic Spark Timing (EST) or by-pass circuits will cause ECM to turn on SERVICE ENGINE SOON light and confirm fault causing Code 42 is present. Refer to appropriate article below:

• TESTS W/CODES - DIESEL
• TESTS W/CODES - GASOLINE
• TESTS W/CODES - TRANSMISSION (If Transmission Codes Are Displayed)