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CMQ
User
Nov 5, 2013, 9:14 AM
Post #1 of 4
(1739 views)
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'94 3.8 V6 misfiring
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I have a 1994 Bonneville with a 3800 V6. Engine was running pretty crappy while driving and the SES light came on. Took it to a local shop and they came back with a fault code of P1361. They said Power Train Control Module. And also suggested the coil packs and ignition control module be replaced. I looked the code up myself and found Ignition Control Citcuit Low Voltage on several websites. I replace the coil packs and ignition control module. Ran like it should for the first couple days. Now it's back to misfiring and running really rough while driving. It seems to run normal when it's idling. It also doesn't misfire as often when the SES light comes on. But until the light comes on it misfires constantly. Just wondering if the code needs to be reset or if the power train control module has somethig to do with it? I've searched all of the online parts stores for the power train control module and haven't come up with anything. Is it called something else besides power train control module?
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 5, 2013, 10:10 AM
Post #2 of 4
(1728 views)
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Re: '94 3.8 V6 misfiring
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*** This information has been updated according to Technical service Bulletin #516522, dated May 1995 .
CIRCUIT DESCRIPTION
The ignition control module sends a spark reference and a fuel control signal to the PCM when the engine is cranking. At the start of crank, the ignition control module controls ignition timing (module mode). When the PCM recognizes the second fuel control pulse, it applies 5 volts to the bypass CKT 424, commanding the ignition control module to switch timing to PCM control. An open in ignition control CKT 423 will set DTC P1350 at start-up. An open in the Ignition Control (IC) circuit or open or grounded bypass circuit at the time the engine is started will set DTC P1361. The engine may be started but will run on module mode timing.
DTC P135O WILL SET WHEN:
- CKT 423 opens during engine run mode.
DTC P1361 WILL SET WHEN:
- Open CKT 423 at the time of engine start-up or grounded CKT 423 while engine is running.
OR
- PCM not commanding IC mode (open or grounded CKT 424) when the engine is started.
ACTION TAKEN (PCM will default to):
When DTC(s) P1350/P1361 are set, the PCM will illuminate the MIL (Service Engine Soon) and remove the 5 volt bypass signal, causing the engine to run on module mode timing.
TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
- Checks to see if PCM recognizes a problem. If it does not set DTC P1350/P1361, it is an intermittent problem which could be due to a loose connection.
- With the PCM disconnected, the ohmmeter should be reading less than 300 ohms, which is the normal resistance of the IC circuit through the ignition control module. A higher resistance would indicate a fault in CKT 423, a poor ignition module connection, or a faulty ignition control module.
- If test light was "ON" when connected from 12 volts to PCM harness terminal "RB15", either CKT 424 is shorted to ground or the ignition control module is faulty.
- Checks to see if ignition control module switches when the bypass circuit is energized by 12 volts through the test light. If the ignition control module switches, the ohmmeter reading should shift to over 6,000 ohms.
- Disconnecting the ignition control module should make the ohmmeter read as if it were monitoring an open circuit (infinite reading). Otherwise, CKT 423 is shorted to ground.
DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:
- Poor connection or damaged harness - Inspect PCM harness connectors for backed out terminals "RB15" or "RB16", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection. and damaged harness.
- Intermittent test - Monitor a digital voltmeter connected from affected terminal to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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CMQ
User
Nov 6, 2013, 6:05 PM
Post #3 of 4
(1696 views)
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Re: '94 3.8 V6 misfiring
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Before I go any further I want to make sure I'm tearing into the right part of the car. Searching online I've found several different answers for where the ECM is. Under the glove box, in the engine compartment, under the dash on the driver's side. Looking in a Hayne's Repair Manual it says "right hand side of the instrument panel". Are they calling the whole dash the instrument panel and it's under the glove box or are they calling the dashboard on the driver's side the instrument panel?
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 6, 2013, 6:10 PM
Post #4 of 4
(1695 views)
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Re: '94 3.8 V6 misfiring
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It's behind the right kick panel
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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