So I put in a new ignition module
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
So I put in a new ignition module
Had been getting a check engine light and car would suddenly stop running. So, put in a new ignition module and got some software to read OBD1. Had a code 42 EST. Could be an open ground on the bypass line - whatever that is - or a faulty ignition module. So, put in a new, different manufacturer, ignition module. Same thing. Code 42 and tachometer reads -0-. Recheck all connections and seem correct. Where do I go now? What the heck is the bypass line?
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Had been getting a check engine light and car would suddenly stop running. So, put in a new ignition module and got some software to read OBD1. Had a code 42 EST. Could be an open ground on the bypass line - whatever that is - or a faulty ignition module. So, put in a new, different manufacturer, ignition module. Same thing. Code 42 and tachometer reads -0-. Recheck all connections and seem correct. Where do I go now? What the heck is the bypass line?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Have you run the sequence of checks from the GM shop manual ?
I scanned through the testing and it mostly points at open or grounded circuits, bad module and then the dreaded bad computer.
EDIT- I was looking for a site with the testing sequence but I couldn't find it. I found this on the crossfire site. code 42
Typical causes for this code include:
1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM
I scanned through the testing and it mostly points at open or grounded circuits, bad module and then the dreaded bad computer.
EDIT- I was looking for a site with the testing sequence but I couldn't find it. I found this on the crossfire site. code 42
Typical causes for this code include:
1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM
Last edited by ...Roger...; Aug 1, 2010 at 07:18 PM.
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
Yes. Did not have any problem until new ignition module put in, so I rule out problems with ECM, Cal Pak, etc. Old module worked OK except it started giving signs of dying - motor would just stop for no apparent reason. Code 42 codes from OBDC 1 scanning software. Nothing disturbed except to take dist. cap off to get to module. Back on properly. All connections inside dist. are nice, tight and in place.
