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99 century ignition/stalling issue

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Old Mar 31, 2025 | 11:28 AM
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Default 99 century ignition/stalling issue

So I've been chasing an ignition issue for months with no codes. Lots of new stuff and finally think I have it narrowed down, it'll crank no start until i wiggle the purple and yellow wires from the icm to the lower crankshaft sensor it'll fire right up. If I shut it off after it warmed up it will just want to stall out. I rewired the connector, saw an exposed wire about 4 inches down thought that was it but still same issue and can't find where it runs to. Is there a plug it runs to or straight to sensor? It won't give me a code so I don't know if the sensor is bad or just bad wiring further down the line I can't see. Any ideas on how I could check this out before sending it somewhere?
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Old Mar 31, 2025 | 11:47 AM
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I'd like to see the repair you made?
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Old Mar 31, 2025 | 11:58 AM
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I soldered, shrink tubed, taped and put the plastic around it with a standard connector, didn't take pictures sorry. It didn't change anything tho.
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Old Mar 31, 2025 | 01:18 PM
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ENGINE?
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Old Mar 31, 2025 | 01:57 PM
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3.1 v6
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Old Mar 31, 2025 | 05:58 PM
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In order to properly control ignition timing, the PCM relies on the following information:
^Engine load (manifold pressure or vacuum)
^Atmospheric (barometric) pressure
^Engine temperature
^Intake air temperature
^Crankshaft position
^Engine speed (RPM)

The Ignition Control (IC) system consists of the following components:
^Ignition coils
^Ignition control module
^7X crankshaft position sensor
^24X crankshaft position sensor
^Powertrain control module
^All connecting wires

The electronic IC Module connector terminals are identified as shown in the Electronic Ignition System graphic. These circuits perform the following functions:
^3X reference high-The 7X crankshaft position sensor sends a signal to the electronic ignition control module which generates a reference pulse that is sent to the PCM. The PCM uses this signal to calculate crankshaft position and engine speed (also used to trigger the fuel injectors).
^3X reference low-This wire is grounded through the ICM and assures the ground circuit has no voltage drop between the ICM and the PCM.
^Ignition control bypass-During initial cranking, the PCM will look for synchronizing pulses from the camshaft position sensor and the 7X crankshaft position sensor. The pulses indicate the position of the #1 piston and the #1 intake valve. Five volts is applied to the bypass circuit at precisely the same time these signals are received by the PCM. This generally occurs within one or two revolutions of the crankshaft. An open or grounded bypass circuit will set a DTC P1351 and the engine will run at base ignition timing. A small amount of spark advance is built into the ignition control module to enhance performance.
^Ignition Control (IC)-The PCM uses this circuit to trigger the electronic ignition control module. The PCM uses the crankshaft reference signal to calculate the amount of spark advance needed.
^24X reference signal-The 24X crankshaft position sensor increases idle quality and low speed driveability by providing better resolution at a calibrated RPM.
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Old Mar 31, 2025 | 05:59 PM
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Will it pass a wiggle test now?
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Old Apr 1, 2025 | 05:40 PM
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So we got to looking and tracing the wire underneath... The damn plug was halfway out, not clipped in. No idea on that one. 😂😂
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Old Apr 1, 2025 | 05:42 PM
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Originally Posted by carfixer007
Will it pass a wiggle test now?
Wiggle test good 👍🏼
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Old Apr 2, 2025 | 01:07 PM
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So no more issues?
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