Electronic Spark Control Module
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
The ESC is also called the knock module. It provides an interface between the knock sensor screwed into the engine block and the ECM. On earlier cars it was located near the evaporator housing (I think?) on later cars it was incorporated into the memcal in the ECM. When the ECM detects knock (pre-ignition), it will retard the timing to save the engine. This will sometimes result in a loss of power.
Usually a code will be thrown if it fails. If it fails "silently" your ECM will not be able to detect any pre-ignition due to bad gas, improper timing, etc. and you may damage your engine (unlikely for an unmodded engine in the short-term).
Usually a code will be thrown if it fails. If it fails "silently" your ECM will not be able to detect any pre-ignition due to bad gas, improper timing, etc. and you may damage your engine (unlikely for an unmodded engine in the short-term).
Last edited by Dale1990; Dec 19, 2006 at 09:18 AM.
Team Owner
Joined: Jan 2003
Posts: 20,304
Likes: 240
From: Summerland B.C. Canada
Read this 
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
1989 Corvette right? The ESC module is located on the passenger side close to the blower motor and behind the fender gill. The module sends voltage readings to the ECM. There is also a knock sensor in the block on the passenger side. Anytime a knock is felt by the sensor...the module stops the voltage to the ECM and the ECM retards the timing.
You can test the ESC system by idling the engine to ~1,500-2,000 RPM and use a hammer (something thin and solid) and with about half strength..tap the block next to the knock sensor. The idle should drop if the system is working correctly. I think the link AGENT 86 posted states all of this and more.
You can test the ESC system by idling the engine to ~1,500-2,000 RPM and use a hammer (something thin and solid) and with about half strength..tap the block next to the knock sensor. The idle should drop if the system is working correctly. I think the link AGENT 86 posted states all of this and more.
