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Tool Hut
Tool Hut, ASE Certified Technician
Category: Buick
Satisfied Customers: 550
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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Buick regal 1990 3.1L INGTION SPARK TIMING CODE 42 what part

Customer Question

buick regal 1990 3.1L INGTION SPARK TIMING CODE 42 what part is bad.
Submitted: 1 year ago.
Category: Buick
Expert:  Dan replied 1 year ago.

Hello, my name is***** code set immediately if reset?

Customer: replied 1 year ago.
if you unhook battery codes reset . but as soon as you start car check engine light comes on . scanner says ignition spark timing code 42
Expert:  Dan replied 1 year ago.

How does vehicle run?

Customer: replied 1 year ago.
rough ideal some missing when you give it gas.
Expert:  Dan replied 1 year ago.
It sounds like your PCM has failed. With the key off, disconnect the Powertrain Control Module (PCM) and then turn the key back on. Connect an ohmmeter from ground to terminal C8 on the Black Powertrain Control Module (PCM) connector. The resistance value should read less than 500 ohms.With the ohmmeter still connected to the White wire at terminal C8, connect a conventional test light to Battery Positive (B+) and then probe terminal C7, Tan/Black wire on the Black connector. The test light should not light. With the ohmmeter still connected to terminal C8, look back to the ohmmeter. The value should have switched from under 500 to over 2000 ohms. If this switching did not take place, check the White wire for a short to ground or Tan/Black wire for an open. If both wires are OK, replace the ignition module but since you already did that is probably fine. If the ohm value switches from under 500 to over 2000 ohms, the module and its wiring should be OK. The problem then would be poor connections at the PCM or failure of the PCM itself. Let me know how it goes or if you have more questions, thanks.
Customer: replied 1 year ago.
where is the powertrain control module located
Expert:  Dan replied 1 year ago.

The PCM is same as ECM, I just seen you already replaced it?

Customer: replied 1 year ago.
have any other idea what it would be?
Expert:  Dan replied 1 year ago.

This code pretty much means ignition module, wiring, or ECM. So at this point I'd run new wiring between ECM and ignition module. Let me know how it goes or if you have more questions. Thanks.

Expert:  Dan replied 1 year ago.

The tan/black wire is the wire this code is specifically about so just replace that wire.

Customer: replied 1 year ago.
ok ill will try it. thank.
Expert:  Dan replied 1 year ago.

No problem, keep me updated. Thanks.

Customer: replied 1 year ago.
I tried replacing the black and tan wirer. it didn't work . unhooked the battery to reset code . then started the car the same code came up again code 42 ignition spark timing, I paid 29.00 for this information and it didn't work . do you know what is wrong with code or not. if not I feel I should get my money back.
Customer: replied 1 year ago.
pleases let me know . what is going on thank you.
Expert:  Dan replied 1 year ago.
Since ignition module and wiring have been replaced that would leave the ECM as the only other possible cause. You can look on www.car-parts.com for a used ECM in your area. Let me know if you have more questions or run into questions. You can get a refund back at any time, thanks.
Customer: replied 1 year ago.
I tried the old ecm. then tried the new ecm . unit both of them came up same code 42 ignition spark timing. unhooking battery both times before hooking up the ecm units. any more thoughts.
Expert:  Dan replied 1 year ago.

Strange, I'll open question up to see if someone else has some ideas. If no one else is able to help your always able to get a refund. Thanks.

Expert:  Tool Hut replied 1 year ago.

Hi my name is***** do not disagree with the direction Dan had you go. I would like to address the miss under acceleration. If there is a misfire you will get a 42.

I assume you had the code 42 before you started changing parts. Please clarify if I have made a bad assumption.

Can you get a spray bottle and spray the wires and see if the miss gets worse or you can see arcing?