Code 42

[pomai]

Code 42,(Ignition Control Circuit) Check the wiring and connectors between the ingnition module and PCM. Check the ignition module. Replace the PCM

What is the PCM? and whats the differance between, ECM and PCM?

Thanks, Ed

 

[GMC Truck]

PCM = powertrain control module
ECM = engine control module
Newer cars and trucks also now have a BCM which is a body control module.

 

[Thunder]

Many times a bad magnetic pick- up coil in the dist will cause a 42.
Also a bad dist module or bad connection. How old are the parts in the distributor?
If you have an ohm meeter test between the 2 leads that come off the pick-up coil.
should be 500-1500 ohms. Best to test it after the engine is warmed up.
On TBI the ECM and PCM is the computer. It can be called by either.
On newer cars that have electronic trans they started calling the ECM a PCM.

 

[ACannell]

Hey I'm not alone! I have an infrequent re-occuring code 42. I paid 350 to have a shop trouble shoot this and he found a bad dist. mod + one bad wire bwt PCM & Dist. The burb runs much better when the engine light is off and a little rough when its on. The light will remain off for a while, then when I shut it off and restart the light comes back. Anyone have any adice here?

 

[eagle mark]

I may sound like a skipping record her but anytime you have issues that involve the ignition module in the distributor have the parts store check it three times. If it fails any of those three it's bad. It is the only piece on these systems that I say to replace with a good one first. I usually preach diagnose the part!

 

[ACannell]

ok Fair enough. How does one diagnose such a part? What kinda books would give me this info?

 

[eagle mark]

Factory Service Manual if your lucky enough to have a freind that works there... or read the sticky for error codes top of the forum and download the trouble shooting codes near the bottom...
http://coloradok5.com/forums/showthread.php?t=240425

http://www.northidahooffroaders.com/fuel-injection/TBIcodes.pdf

I have a hand full from the JY and run one for a month or so and if no issues it goes to the good pile. I have seen so many of these glitch even after a test...

 

[ACannell]

Dude you rock. I just downloaded the pdf and will begin my diagnosis asap. I read a little and did not understand all of the acronyms. Is there a glossary or such?

 

[munepit]

Is code 42 four flashes,pause, two flashes? Thanks

 

[ACannell]

absolutely