check engine light wont come on

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Feb 21, 2011 | 01:08 PM

93f150guy

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check engine light wont come on

i have a 2002 f150 5.4L 4x4 and it is driving me crazy. for over a year now my check engine light will not come on when there is a problem. i have had to replace 3 coil packs and none of them have made the check engine light come on, and now its on seven cylinders again and its a pain in the a$$ trying to figure out problems with it with no engine light. last month the spark plug blew out of the head and the engine light still didn't come on. any body have any ideas why it will not come on? i am sooo close to selling this truck because its such a pain, but i like the way it looks a lot so i'd prefer to keep it. PLEASE help, thanks

Feb 21, 2011 | 04:57 PM

Ultramagdan

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Joined: Feb 2000

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From: Kansas

When you first turn the ignition on (don't start it), does the check engine light light up with the rest of the other lights?

Feb 21, 2011 | 05:22 PM

93f150guy

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yes it does

Feb 21, 2011 | 07:12 PM

projectSHO89

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From: St Louis

You misunderstand the purpose and function of the MIL.

Feb 22, 2011 | 04:02 PM

pawpaw9

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Try checking your TPS. Mine went out and it ran like a 3 legged dog and the light didn't come on. If you do have to replace it save your self some trouble and get the motorcraft brand.

Feb 23, 2011 | 12:04 PM

Justin's Green Truck

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Not everything on the engine is monitored. Some components will fail and never set a check engine light. There are certain thresholds that have to be met during a number of drive cycles in order for the check engine light to be illuminated.
Scan your vehicle and see if there are any faults stored. There may not be since the check engine light is not on. Or they may be old ones that havnt been reset.

Feb 23, 2011 | 08:43 PM

screamin gt

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Joined: Oct 2010

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or there could be pending codes that just have not set yet.

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Jul 7, 2024 | 10:54 AM

Johnny Paycheck

Fleet Mechanic

Joined: Jul 2019

Posts: 1,315

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The OP of this thread hasn’t been here since 2015, so I doubt he’ll be back to answer.

Feel free to post a new thread and spill all the beans about your truck and what is happening and you may get some looks and help.