Where is the timing connector on a 1997 GMC Yukon?
Turn off the engine and leave the ignition key in the off position. Disconnect the timing connector located on the main wiring harness. The main wiring harness in the 1997 Yukon runs behind the engine, along the firewall, in the rear of the engine compartment.
How does a GM Electronic spark control module work?
This module is essentially a small computer, and can determine the exact location of the engine knock. The control module can then adjust the timing of the engine to compensate and eliminate the vibration. Often, compensating for an engine knock requires engine timing to be slowed, leading to a temporary reduction in power.
When to use code 42 electronic spark timing circuit?
Code 42 – Electronic Spark Timing Circuit (EST) Circuit Description When the system is running on the Ignition Module, that is, no voltage on the by-pass line, the Ignition Module grounds the EST signal. The ECM expects to see no voltage on the EST line during this condition.
What causes a GM spark control to knock?
Spark Control Causes The Electronic Spark Control, also called the Knock Sensor, is an electronic device built by General Motors to help regulate the timing inside of the engine. When combustion inside the engine does not fire properly, a “spark knock” or abnormal vibration can occur.
Why does my GMC Yukon engine not start?
GMC Yukon: Engine Cranks → Won’t Start There are a lot of issues that can cause your Yukon to crank, but not start. The engine needs air, fuel, and a spark in order to run. It is highly likely that if the engine is cranking, but not starting that it has thrown an OBDII code.
What is the trouble code for spark timing?
GM Code 42 Electronic Spark Timing or Bypass Fault. Trouble Codes › GM OBD Trouble Codes › GM Code 42. Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.
This module is essentially a small computer, and can determine the exact location of the engine knock. The control module can then adjust the timing of the engine to compensate and eliminate the vibration. Often, compensating for an engine knock requires engine timing to be slowed, leading to a temporary reduction in power.
Spark Control Causes The Electronic Spark Control, also called the Knock Sensor, is an electronic device built by General Motors to help regulate the timing inside of the engine. When combustion inside the engine does not fire properly, a “spark knock” or abnormal vibration can occur.