{"id":82937,"date":"2025-03-23T09:02:48","date_gmt":"2025-03-23T16:02:48","guid":{"rendered":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/?p=82937"},"modified":"2025-03-27T08:10:52","modified_gmt":"2025-03-27T15:10:52","slug":"code-p1374-2003-chevy-monte-carlo-ss-3-8-liter-engine-no-spark","status":"publish","type":"post","link":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2025\/03\/code-p1374-2003-chevy-monte-carlo-ss-3-8-liter-engine-no-spark","title":{"rendered":"Code P1374 2003 Chevy Monte Carlo SS 3.8 liter engine No Spark"},"content":{"rendered":"\n

Hi Jaxer, My name is Bruce XXXXXX. My car was bucking and jerking at idle and a little black smoke was coming out the tailpipe. Now it has no spark and won’t start. Trouble code P\/1374 was set. Crankshaft sensor 3x reference circuit.
I took an ac voltage measurement of the 3x crank sensor while cranking. I took the measurement at the ignition module where the sensor harness comes from the sensor to the module.
A light blue wire with a white stripe. It measured 1.7 to 2.8 ac volts. while cranking.
I measured the 18x signal wire, a yellow wire at the ignition module while cranking it shot right up to 3.5 ac volts with no minimum voltage. I used a digital multimeter. Wouldn’t the 18x wire reduce the voltage reading as it passes the open gaps on the reluctor wheel? Is my snap on multimeter too slow to read the change? Do I need a lab scope?
Can you check my voltage readings against a good service manual?
The ignition module has battery voltage reading on the pink wire and good ground.
The crank sensor has 10 volts while cranking and a good ground just like the manual said. 3 months ago i had an intermittent no start, cranked over fine. Engine would lope at idle, stall and upon restart it would idle and run fine.
If my signal wire voltages check out What’s an easy way to check an ignition module. Thanks a lot. Bruce XXXXXX<\/p>\n\n\n\n

I have another question i saw online that if you turn the crankshaft by hand and measure the dc voltage on the 18x and 3x signal wires at the ignition module it should read o volts off and 5 to 6 volts on. what do you think of this test? bruce XXXXXX<\/p>\n\n\n\n

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My Thoughts<\/strong><\/p>\n\n\n\n

Sounds like you may have more than one thing going on here. After an initial read and thinking of all the common part failures for these. I think the no spark is ignition module replacement needed and the early on stalling were indication of this part failing. I noticed the p1374 code is different for the 3.4L and the 3.8L engine. So I added the Code P1374 info for the 3.8L Specific engine below. Easiest way to test an ignition module is to replace it. And with Free Returns options out there… Just sayin’. I did not find any information on testing the module in the manual. <\/p>\n\n\n\n

The 3X reference signal is produced by the ignition control module (ICM). If the PCM detects an incorrect number of pulses on the 3X reference circuit, the DTC\u2009P1374 sets. So what I get from this would be the module is not doing its job and sets the code. Without the 3x reference(ICM) the PCM can not do its job(start the dang engine). You are getting readings on the wiring, so the wiring is most likely fine. <\/p>\n\n\n\n

If it was mine, I would order a new module and try it to save time. I looked up the ignition module and found this one that comes with coils for about the some money. You figure the coils are probably just as old as the Ignition Module. <\/p>\n\n\n\n

New Ignition Control Module<\/strong><\/a> <\/a><\/strong><\/p>\n\n\n\n

\"Ignition<\/a><\/figure>\n\n\n\n

Code P1374 3.8L Specific<\/h2>\n\n\n\n

DTC P1374<\/h3>\n\n\n\n

Circuit Description<\/p>\n\n\n\n

The 3X reference signal is produced by the ignition control module (ICM). The ICM calculates the 3X reference signal by dividing the crankshaft position (CKP) sensor 18X pulses by 3 when the engine is running and CKP sync pulses are also being received. The powertrain control module (PCM) uses the 3X reference signal to calculate engine RPM and crankshaft position at engine speeds above 1,200\u2009RPM. The PCM also uses the pulses on this circuit to initiate injector pulses. And the PCM constantly monitors the number of pulses on the 3X reference circuit and compares the number of 3X reference pulses to the number of 18X reference pulses and CAM signal pulses being received. The PCM will use the 18X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 18X reference and camshaft position PCM input signals only. If the PCM detects an incorrect number of pulses on the 3X reference circuit, DTC\u2009P1374 sets. Conditions for Running the DTC<\/p>\n\n\n\n

The engine is running for more than 3\u2009seconds. Conditions for Setting the DTC<\/p>\n\n\n\n