New the TBI world

[Muddytazz]

42 Electronic Spark Timing (EST) circuit

What is this and what would cause this?

 

[Cricket]

Here's a good code reference site Jeff.

http://www.chevythunder.com/fuel injection troubleshooting pg a.htm

CODE 42: Code 42- This code will be set when the engine is running at 600 rpm or greater, and there is no pulse on the white wire from the ecm to the ignition module for more than 200ms (milliseconds). Common causes for this code include bad connections, frayed wiring, or broken wires such as the tan/black (ecm pin D5) purple/white( ecm pin B5) or white wire (ecm pin D4). Check your wiring carefully along with the connections back to the ecm.

This might help explain it a little better: http://www.troublecodes.net/articles/gmmsundrstd42.shtml

 

[Muddytazz]

I recently found the tan/black wire completely disconnected from it connector just after coming out of the firewall into the engine compartment. Looks to me like it goes to the ecm on one side and the aldl connector under the dash on the other side? I reconnected the connector, would this of caused the code?

 

[dyeager535]

I didn't have this issue, but I *believe* it's typical when you set the timing, which requires disconnecting that wire.

Plug it in, pull your ECM fuse for 10 seconds, reinstall, and see what happens.