Code 42

[That GN Guy]

Code 42 popped up while stopped at a red light. Drove home easy with no issues.

Ran the trouble shooting tree and it pointed at ignition module. 2 duralast modules, same problem. Today I installed a highway stars AC Delco module, same problem. Cleaned the ECM connectors and checked ECM pins. Removed and reseated TT chip. Same problem.

Pin A and B on the ccci harness are not shorted via test light. Ohmed to .3 and .4 ohms respectively with ECM and ccci disconnected. The meter had an extension wire to ECM connector and ccci harness, they were tested at the terminal, not puncturing the wire.

Bad ECM? Not sure what step to take next. It starts with no issues, runs but not the best. Code 42 and check engine light pops up within about 10 seconds. Did the same thing with every module. The ECM is a reman of unknown origin, but drove great for maybe 10 hours.

 

[hensleyt]

 

[hensleyt]

is this the tree you used?

 

[hensleyt]

there more

 

[That GN Guy]

That is the tree I used, never got the switch to 8000 ohms. Looked for an open circuit or grounded wire on the est and bypass wire, they tested fine.

 

[hensleyt]

Two ignition modules and ECU I would think its a interment wiring harness problem. Got to be the hardest thing to diagnose
If it helps ill be scratching my head and pondering over your problem and grateful its not mine
the poor performance is because it not switching to ECU timing but remain on module timing
it looks like step 5 is your brick wall and 424 and 423 is where it starts

 

[hensleyt]

but you say it test good witch points to ignition module
if your in az I have a none good OEM you can try.

 

[SCOOBY DOO]

Malfunction Codes Reference

ECM Trouble Codes and Diagnostics for Buick 3.8l SFI Turbo V6

www.gnttype.org

 

[salvageV6]

What MAF or Translator are you using? Any timing control modifications on the EST white wire?

 

[That GN Guy]

OEM MAF, I haven't upgraded yet, no translator. Est wire hasn't been modified but I can see it's been probed before near the ECM connector. This car has sat for 16 years and I resurrected it within the last 2 months. It has accel plug wires, but they've been there since I bought the car.

The test light I'm using is a 6/12 volt LED light. I wonder if that's misleading me. I'm going to look for a 12v incandescent and try that.

 

[salvageV6]

I'd use a good digital voltmeter and an ohm meter to check those circuits.
Ohm meter for continuity on the wiring with connectors unplugged.

 

[That GN Guy]

I borrowed my wife's fluke meter and got the same results. White, and tan/black wire ohmed out to .3 with ECM and ccci disconnected. Ran the tree again with an incandescent 12v test light and got the same results. Module will not switch from sub 200 to over 8k.

A previous module had the test light stay on, the Delco one I just installed didn't do that. 3 bad modules in a row or am I missing something?

I live in Louisville KY if anyone is willing to lend a spare.

 

[hensleyt]

the incandescent test light is the correct tool.
Meter is reading 200 at B4 white wire.
Test light hooked to ground. when you make contact to D5 the light should light and it should switch to 8K
this is done in the car at the ECM. if it doesn't switch. to 8K
Then go under the hood to the module
hook your meter to A connector it should read 200 if not you have a open between A and B4. if you do then
with test light to ground touch the B dose it light ? If not you have a open between B and D5.
you can now hook the test light to 12V touch B and it should switch.
clear as mud know?

 

[hensleyt]

Or you can pull the two plugs of the ECU and module and just make sure the wires are not open and do the wiggle test on the wires.

 

[hensleyt]

correction that 5V !!!!

 

[hensleyt]

Ok let me re think my #13 post I thought for sure I had thought it through before I pushed post. I see some flows in my think and typing
Im thinking you have a open wire between the ECU and module
The test needs to be done at ECU and again at the module.
Im heard lots of complaint about new modules I think Casper has a test tool

 

[turbojay]

I struggled with a similar issue for years in my GN. The car would run fine for a while, then it would throw a code 42, and sometimes die few minutes after the code popped up, other times it just ran with limited power. The issue turned out to be with the ECM, I bought a known good EMC from a low mile GN and issue was gone.

 

[That GN Guy]

Thanks for all the replies so far. I ran the tree again with my wife today and got the same results. But we called around and found a store with a machine that could test the module. AutoZone of all places.

The original and replacement Delco unit passed 6 times. I'm going to disassemble the ECM connector for inspection and order an ECM tonight.

 

[That GN Guy]

ECM connector terminal B4 was a little miss shapen from probing and it would not hold onto an ECM pin on it's own. Depinned and corrected. ECM connector terminal D5 was in good shape. Reseated calpack and chip.

Took some offline advice and changed the crank sensor.

Still have code 42. New ECM is on the way.

Are the wires from the ECM to the c3i a straight run or is there a junction somewhere?

 

[TurboBob]

ECM connector terminal B4 was a little miss shapen from probing and it would not hold onto an ECM pin on it's own. Depinned and corrected. ECM connector terminal D5 was in good shape. Reseated calpack and chip.

Took some offline advice and changed the crank sensor.

Still have code 42. New ECM is on the way.

Are the wires from the ECM to the c3i a straight run or is there a junction somewhere?

direct from ECM to ignition module.