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What kind of tool i can use to check signal at the coils connector/crankshaft sensor/camshaft sensor?

2004 GMC Envoy SLT 4.2L the engine will turn over but want start no spark at the spark plugs boots how to find the problem and fix it do anybody know the right answer to my questions? it would be a big help to me. i believe somebody have had the same problem relate to mind.

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  • Joe Russell Dec 03, 2016

    yes i use a Innova 3040c scan tool but i didn't notice the engine service light on when driving, the vehicle was running good before turn the engine off after turn the engine off then it wouldn't start up again just don't show no spark when check for spark the engine act like it want to start sometime but something is not letting the spark plugs fire i don't know what that could be, the battry cable was disconnect before i use the ob2 scan tool will that erase codes when disconnect the battry cable? the battry went dead so i took it out to charge it i couldn't use a scan tool with a dead battry, i hope to get to the root of the problem so i can fix it the only codes it show now is P2101, and P1516 i don't know what codes was there before i disconnect the battry cable hope some can help me thank you.

  • Ron Nelson
    Ron Nelson Dec 03, 2016

    Both codes point to Throttle control module throttle actuator position

    Read more:

    That's where I would start. Car computers will sometimes just not send spark when sensors (or wiring to sensors) go bad.

  • Ron Nelson
    Ron Nelson Dec 03, 2016

    More info

  • Joe Russell Dec 04, 2016

    where is the purge control solenoid and powertrain relay located?

  • Ron Nelson
    Ron Nelson Dec 04, 2016

    Here is a link for the purge control solenoid. It's a 2002 but at least will give you the idea.

    To find yours as it may be different, just Google your year make model and purge control valve and then you can see what it looks like and help you identify it.

    And here's a link for your fuse box



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  • 21 Answers

Have you tried a obd2/can code scanner? Usually the sensors like crank/cam will though a code to the computer and a code scanner will tell you what's wrong about of the time

Posted on Dec 03, 2016


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1 Answer

How do i test a coil over plugs with a multimeter?

the problem is before the coils
check cam and crank position sensors for operation
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run the fault codes first

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If i replace an crankshaft position sensor do i have to reset anything?

maybe you got the wrong sensor, but you shouldn't have to reset any thing

Dec 14, 2016 | 2004 GMC Envoy

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How does the crankshaft position sensor operate what is it Job to do? and how do i test the injectors for pulsa with a noid light where are the injectors located on this vehicle?

The crank sensor is needed for the coils to fire. It is on the drivers side, mounted in the engine block back by the transmission. The injectors are under the plenum. The plenum wraps around them. I wouldn't worry about them right now. And your probably right about being flooded. I would throw new plugs in it when you replace the sensor.

Dec 11, 2016 | 2004 GMC Envoy SLT

1 Answer

Where is the purge control solenoid and powertrain relay located on 2004 Envoy SLT 4.2L?

Powertrain relay ? Maybe you mean IGN 1 relay ? This supplys B+ power to the coils . relay # 58 in the under hood fuse box .
Is there B+ voltage at the coil's pink wire ?
Evaporative Emission (EVAP) Canister Purge Solenoid (LL8)
On the left side of the engine block
Engine Controls Component Views in Engine Controls - 4.2L
Engine Controls Connector End Views in Engine Controls - 4.2L
Evaporative Emission (EVAP) Canister Purge Solenoid (LM4)
On top of the engine, toward the front
Google picture of solenoid so you know what your looking for .

Dec 04, 2016 | 2004 GMC Envoy SLT

1 Answer

How do i check the trigger side of the ignition coil? what is all the things that will cause no spark at spark plugs boot?

What are the fault codes in memory for this problem, if you haven't run that test borrow an OBD2 code reader and do the test.

Dec 02, 2016 | GMC Cars & Trucks

1 Answer

Do a 2004 Envoy SLT 4.2L have a Ignition Module?

Crankshaft position sensor,cam sensor . your vehicle should have coil on plug , a coil at each spark plug !
Ignition Coils
Each ignition coil has an ignition 1 feed and a ground. The PCM supplies an ignition control (IC) circuit. Each ignition coil contains a solid state driver module as its primary element. The powertrain control module (PCM) signals the coil driver to initiate a firing event by applying a signal to the IC circuit at the appropriate time. When the signal is removed, the coil fires the spark plug. The spark plugs are tipped with platinum for long wear and higher efficiency.
During normal operation the powertrain control module (PCM) controls all ignition functions. If either the crankshaft position (CKP) or camshaft position (CMP) sensor signal is lost, the engine will continue to run because the PCM will default to a limp home mode using the remaining sensor input. As mentioned above, each coil is internally protected against damage from excessive voltage. If one or more coils were to fail in this manner, a misfiring condition would result. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.
If a crank sensor is replaced a Crankshaft Position System Variation Learn must be done and a scan tool is need to do this.

Nov 30, 2016 | 2004 GMC Envoy SLT

1 Answer

The engine will crank but will not start why?

Do you have any codes or an engine light on, in your dash board ? Have you checked for spark at your plugs ? There are many things that could cause a vehicle to not start. Bad camshaft/crankshaft sensors. Poor ground wiring. Defective spark plugs or wires/coils.

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