Code 42 problem

Reply Subscribe

Thread Tools

Search this Thread

Mar 2, 2013 | 01:23 PM

farmer661

Thread Starter

Intermediate

Joined: Oct 2012

Posts: 39

Likes: 3

From: Lufkin Texas

Code 42 problem

My 84 Crossfire started to run poorly and puts out a Code 42. I went through the testing procedure in the FSM which suggests the ECM. I bought a used ECM and installed my old chip, without success.

Using a timing light, the timing clearly doesn't advance. The code comes up again in seconds after starting the engine even after clearing the ECM. I have checked continuity and unwanted grounds.

It looks like I start replacing parts. Looking at the FSM electrical Supplement, I think the only components in question are the pickup coil, module located in the distributor, ECM, and the chip.

Any ideas or helpful hints are appreciated.

Regards,
Ken

Mar 2, 2013 | 01:39 PM

blackbear bob

Racer

Joined: Dec 2006

Posts: 499

Likes: 27

From: shapleigh maine

Most likely cause is the HEI module, but proper testing of the entire circuit is key. Pay particular attention to the ECM connectors. They are old and fragle. Are you seeing 2.0 to 4.5 volts AC on terminal 19 at the ECM?

Mar 2, 2013 | 02:06 PM

farmer661

Thread Starter

Intermediate

Joined: Oct 2012

Posts: 39

Likes: 3

From: Lufkin Texas

Step #2 in the FSM is to disconnect A and C at the distributor connector, then the voltage to ground on A (#19) should be 2 to 4.5 VAC. I assume this is the check you describe. It passed this test.

I will relook at the terminals at the ECM, then probably get a new ignition module.

Thanks for the feedback.

Ken

Mar 2, 2013 | 02:15 PM

blackbear bob

Racer

Joined: Dec 2006

Posts: 499

Likes: 27

From: shapleigh maine

Yes and good luck.

Mar 3, 2013 | 08:03 PM

mechanicmattc

Heel & Toe

Joined: Feb 2013

Posts: 22

Likes: 0

From: Richmond KY

I had the same issue with my 84 about six months ago. I checked all of the wiring and changed the ignition module. Still had the code 42, the service engine light would come on about ten seconds after the car was started. It was doing all kinds of crazy #%&^, backfiring, stumbling, etc..... I pulled the ECM and found this, may not be your problem, but no harder than it is to pull out and remove the cover. Might be worth while to check, if you still have the issue after you change the ignition module.

Mar 9, 2013 | 08:29 PM

farmer661

Thread Starter

Intermediate

Joined: Oct 2012

Posts: 39

Likes: 3

From: Lufkin Texas

An update. Had the ignition module checked at Autozone (not sure how reliable that is) and it is OK.

I rechecked the wire continuity between the distributor and ECM. I noticed that two of the wires (A and C) have a 10 and 20 ohm resistance, respectively. The other two (B and D) have zero resistance. Is this significant enough to give a Code 42?

Thanks in advance,

Ken

Mar 9, 2013 | 09:15 PM

blackbear bob

Racer

Joined: Dec 2006

Posts: 499

Likes: 27

From: shapleigh maine

Should have 0 or close to it on all four wires. The search continues, but you are getting closer. Bob

Mar 11, 2013 | 02:58 PM

farmer661

Thread Starter

Intermediate

Joined: Oct 2012

Posts: 39

Likes: 3

From: Lufkin Texas

Problem resolved! Connector that you disconnect to set the timing had 20 ohms across it. Used crocus cloth and electrical contact cleaner and it went to zero ohms. Car now has no codes. I was surprised the system was that sensitive.

A lesson learned. A free fix that I threw $200 at. Thanks for the post, Black bear bob!

Ken