I got a code 42 on my 88 today. My manual says check wiring to ignition module and ecm. replace ignition module. replace ecm. I guess i need to buy a ign. module and a remanufactured ecm from Ecklers. My question is could it just be the chip in the ecm or should I get a remanufactured ecm and use the chip I now have. How can I be sure it is not the chip? What's has your experience taught you?

 

Im no expert here, maybe I can help a little. Code 42. When the system is running on the ignition module, that is no voltage on the bypass line, the ignition module grounds the EST signal. The ECM expects to see no voltage on the EST line during this condition. If it see's voltage it sets code 42 and will not go into EST mode.


Do you have a FSM? there is a complete dianogisic chart for code 42.

Maybe some one can post there page out of a FSM.

Dont go buy parts untill you diagnos it properly.

Good luck

Corvette Mike

 

[QUOTE=CorvetteMike2004;1570279125]Im no expert here, maybe I can help a little. Code 42. When the system is running on the ignition module, that is no voltage on the bypass line, the ignition module grounds the EST signal. The ECM expects to see no voltage on the EST line during this condition. If it see's voltage it sets code 42 and will not go into EST mode.


Do you have a FSM? there is a complete dianogisic chart for code 42.

Maybe some one can post there page out of a FSM.

Dont go buy parts untill you diagnos it properly.

Good luck

Thanks Mike, I only have a Haynes manual. I could use that diagnostic chart for code 42 if someone cold post it. Ecklers wants $99 for ecm and $89 for ign. module.

 

The problem could be as simple as the EST bypass connector is unplugged, loose, or you recently unplugged it to set the timing and failed to clear the the code. Have you tried to clear the code ??
http://members.shaw.ca/corvette86/Code%2042.pdf

 

thanks 86. with that info i am sure we will get this thing done without help from 99.