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Gary
Gary, ASE Certified Technician
Category: Saturn
Satisfied Customers: 15728
Experience:  22 years GM master tech..ase mater tech
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Same code same engine Replaced plugs boots coil pack icm 't

Customer Question

Same code same engine
Replaced plugs boots coil pack icm don't know what to do next
Submitted: 5 months ago.
Category: Saturn
Customer: replied 5 months ago.
Code p0340
Expert:  Gary replied 5 months ago.

how does it run ?

once cleared how soon before that code sets ?

Customer: replied 5 months ago.
Runs good no knocking not sluggish. Isn't choking. Came on after 7 miles this last time. Usually comes on under 10.
Expert:  Gary replied 5 months ago.

that is the only code being set ?

any access to a scan tool ?

Customer: replied 5 months ago.
Only code just had it scanned at AZ. It shows it twice like 2 separate codes but the exact same code.
Expert:  Gary replied 5 months ago.

any access to a scan tool ?

Customer: replied 5 months ago.
No not other than running back to AutoZone
Expert:  Gary replied 5 months ago.

with that code it usually is a bad ICM or computer

is the wiring good from the ICM to the computer ?

Customer: replied 5 months ago.
I tried to trace it from the harness but it gets bundled with a bunch of other connections and couldn't really see where it leads too. I just read that the computer is to the right of the engine in front of the fuse panel is that correct? Should I try to clean the harness somehow?
Expert:  Gary replied 5 months ago.

the ECM is under the hood # ***** as seen here in this picture

if the wiring to it looks good replace the spark plugs if it still sets this code replace the ignition module complete assembly if it still acts up and the wiring is good from the ICM to the ECM then the ECM is bad

most of these end up being spark plugs or the ignition control module assembly being bad setting this code

This ignition system does not use a conventional camshaft position (CMP) sensor that detects valve train position. The ignition control module (ICM) detects when #1 or #3 cylinder has fired on the cylinders compression stroke using sensing circuitry integrated within each coil. The sensing circuit detects the polarity and the strength of the secondary voltage output. The higher output is always at the event cylinder. The ICM sends a CMP signal to the engine control module (ECM) based on the voltage difference between the event and waste cylinder firing energy. This system is called compression sense ignition. By monitoring the CMP and crankshaft position (CKP) signals, the ECM can accurately sequence the fuel injectors. If the ECM does not receive a CMP signal from the ICM, DTC P0340 sets

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Customer: replied 5 months ago.
Yea I've replaced all of the above except the computer. I even did the plugs twice because I used platinum autolite not the acdelco iridium.
Expert:  Gary replied 5 months ago.

the complete top ignition assembly was replaced ?

if so with this code and 2 sets of plugs it has to be the wiring from the ICM to the ECM or the ECM itself

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Expert:  Gary replied 5 months ago.

how are you making out ?

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