Question about 2004 GMC Envoy SLT

3 Answers

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?

2004 GMC Envoy SLT 4.2L engine will crank but want start no spark at the spark plugs boots the coils is on the spark plugs do the crankshaft position sensor send a signal to the coils and the fuel injectors for the engine to start? i been cranking the engine a lots now but i don't smell any gas the engine should be flooding by now.

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3 Answers

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  • GMC Master
  • 14,585 Answers

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.

Posted on Dec 11, 2016

  • 52 more comments 
  • Joe Russell Dec 11, 2016

    are you saying the crank sensor could be bad causing no spark how do i check for resistance on the crank sensor? do the crank sensor needed for the injectors to work? I'm not sure the injectors is working.

  • Randy Ohler Dec 11, 2016

    The sensor is a pulse generator. There is a tone wheel on the crank. Everytime a tooth passes by the sensor, the sensor sends a signal to the PCM. The PCM reads it and fires a certain coil. The crank sensor does mess with the injectors. The cam sensor is what times the injectors but is not needed to fire them. The PCM fires them even if the cam sensor goes bad. I would check power and ground at the plug first. Usually the outer wires in the plug. If there, then check the sensor pins. If you get no reading or the ohms are in the millions. The sensor is bad. Sorry I can't tell you what the reading should be, I work on to many makes and models. They can range from 17 ohms to a couple thousand ohms. I usually get the new sensor and ohm it and compare the numbers to the old before installing it. If they are real close. I go back and go threw the wiring and check resistance.Any over 5.0 ohms I run a new wire.

  • Joe Russell Dec 12, 2016

    i check for powwer at the plugs with a DT-830B digital multimeter it show 12.3 voltage with key on and i also use a led light at the plugs with key on power at black and purple wire no power at pink wire. with key off power at black, purple and pink wire this is the test i use with the led light what i mean about power the lights on my tester light up when i connect it to the wires at the plugs do power supose to be at all 3 wires when key is off? where do i set the multimeter when checking the resistance on the crank sensor? hope you can help. thank you

  • Joe Russell Dec 12, 2016

    i check for powwer at the plugs with a DT-830B digital multimeter it show 12.3 voltage with key on and i also use a led light at the plugs with key on power at black and purple wire no power at pink wire. with key off power at black, purple and pink wire this is the test i use with the led light what i mean about power the lights on my tester light up when i connect it to the wires at the plugs do power supose to be at all 3 wires when key is off? where do i set the multimeter when checking the resistance on the crank sensor? hope you can help. thank you

  • Joe Russell Dec 12, 2016

    there is codes # in the computer P2101,P1516,P2119 what are the meaning?
    i check for powwer at the plugs with a DT-830B digital multimeter it show 12.3 voltage with key on and i also use a led light at the plugs with key on power at black and purple wire no power at pink wire. with key off power at black, purple and pink wire this is the test i use with the led light what i mean about power the lights on my tester light up when i connect it to the wires at the plugs do power supose to be at all 3 wires when key is off? where do i set the multimeter when checking the resistance on the crank sensor? hope you can help. thank you

  • Randy Ohler Dec 13, 2016

    With key on. You should have one power(12 Volts+) source and one ground. To check ground, put the light on the positive side of the battery. With the key off. It should only show ground, NO power. By what your saying, you either have a short in the wiring or the PCM has died. The three codes you put up are throttle body codes(TAC). There are TSB's on this about bad plug/wires at the plug. If I can remember tomorrow, I will look up diagrams for your vehicle. GM TAC's don't shut done the spark. But if a wire is shorted, this could be a possibility. I'm already on 5 cars, and others lined up.

  • Joe Russell Dec 13, 2016

    to check ground are you saying connect the clip end of the light to the positive cable on the battry or the pointed end of the light to the positive cable on the battry can you send me pictures how to do it? Thanks.

  • Randy Ohler Dec 14, 2016

    Clip to battery+, then check the plug with the pointed end. Sorry I didn't get to look yours up. In the middle of 2 engine rebuilds, replace a transmission and diagnosed 3 cars.

  • Joe Russell Dec 16, 2016

    i connect the clip end of my test light to the battry+ and check the plug with the pointed end i get power at the black wire(ground) wire at the coil connector with the key off do i suppose to get power at black wire with the key off?

  • Randy Ohler Dec 17, 2016

    On this one yes. It is a 3 wire plug. Easiest way to check coils is to pull one leave it plugged in. Insert a screw drive and lay it close to a metal part. Crank the engine, you should see spark. If you have power and ground at the plug, then look to replacing the crank sensor.

  • Joe Russell Dec 17, 2016

    there is no spark at the coil how do i test the old crank sensor?

  • Joe Russell Dec 17, 2016

    there is no spark at the coil how do i test the old crank sensor? how do check for power and ground at the plug?

  • Joe Russell Dec 17, 2016

    there is no spark at the coil how do i test the old crank sensor? how do i check for power and ground at the plug?

  • Randy Ohler Dec 18, 2016

    You have a 3 wire sensor, usually the outer leads are the coil. If it doesn't read or reads high(just a guess 100 ohms +), the sensor is bad. If you suspect it bad after testing, get the new one and check it before install.

  • Joe Russell Dec 18, 2016

    the crank sensor that i remove is a 2 wire sensor, which leads is the coil? if i get a new sensor and it test the same as the old one can i take it back and get a refund?

  • Randy Ohler Dec 18, 2016

    Have you read the ohm,s yet? Read it. Take your Ohm meter with you and read the ohm,s of the new one before you leave the store/pay for it. I have done it many times (No refunds on electrical, unless you have a shop. Credit, yes). Have you check for power and ground at the crank plug? You have ground from your previous post. Do you have power at the plug. Key on. hook the light to the negative side of the battery. Light should be on. If you have power and ground at the crank plug, Just replace the crank sensor. Only 3 things will cause no spark. The crank sensor,wiring, or the PCM.

  • Joe Russell Dec 19, 2016

    when i read the ohm on the old crank sensor it is 0.71 when meter setting on 20k and it read 00.5 when setting on 200k read 000 when setting on 2000k which reading is correct? i use a bosch noid light at the crank plug about a week ago the noid light didn't blink when cranking but i will use a test light to check for power at the crank sensor plug i havn't got the new sensor yet.

  • Joe Russell Dec 19, 2016

    when i read the ohm on the old crank sensor it is 0.71 when meter setting on 20k and it read 00.5 when setting on 200k read 000 when setting on 2000k which reading is correct? i use a bosch noid light at the crank plug about a week ago the noid light didn't blink when cranking but i will use a test light to check for power at the crank sensor plug i havn't got the new sensor yet.

  • Joe Russell Dec 19, 2016

    when i read the ohm on the old crank sensor it is 0.71 when meter setting on 20k and it read 00.5 when setting on 200k read 000 when setting on 2000k which reading is correct? i use a bosch noid light at the crank plug about a week ago the noid light didn't blink when cranking but i will use a test light to check for power at the crank sensor plug i havn't got the new sensor yet.

  • Randy Ohler Dec 19, 2016

    Replace it. 20K setting with a .71 reading is 7100 ohms.

  • Joe Russell Dec 20, 2016

    is 7100 ohms to high of risistance for the crank sensor?

  • Randy Ohler Dec 20, 2016

    Absolutely.

  • Randy Ohler Dec 20, 2016

    The highest I have seen are wheel speed sensors. 1050 ohms.

  • Joe Russell Dec 20, 2016

    what is the numbers range so I'll know what to look for when i check for resistance on the new crank sensor?

  • Joe Russell Dec 20, 2016

    what is the numbers range so I'll know what to look for when i check for resistance on the new crank sensor? if the resistance is high that is what cause no spark at coils and spark plugs?

  • Joe Russell Dec 20, 2016

    what is the numbers range so I'll know what to look for when i check for resistance on the new crank sensor? if the resistance is high that is what cause no spark at coils and spark plugs?

  • Randy Ohler Dec 20, 2016

    I don't know. But 7100 is way high. I check way to many solenoids and sensors to remember. Solenoids run from 11 to 45 ohms. Sensors run from 11 to 1100 ohms. Imports can run higher.

  • Randy Ohler Dec 20, 2016

    High resistance will not let the PCM see a signal. It will shut down the coils.

  • Joe Russell Dec 21, 2016

    i check for power at the coil key on with a test light i connect the clip to the negative side of battry and the pointed to the tan wire at the coil it show power at the first test but now it show no power on the tan wire at the coil what i need to check to get power at the tan wire again? and then i turn the key off i connect the clip to the positive side of the battry and the pointed to the black wire on the coil it show power why it show power at ground? do it suppose to have power at the wires at the cranksensor with key on?

  • Joe Russell Dec 21, 2016

    i check for power at the coil key on with a test light i connect the clip to the negative side of battry and the pointed to the tan wire at the coil it show power at the first test but now it show no power on the tan wire at the coil what i need to check to get power at the tan wire again? and then i turn the key off i connect the clip to the positive side of the battry and the pointed to the black wire on the coil it show power why it show power at ground? do it suppose to have power at the wires at the cranksensor with key on?

  • Joe Russell Dec 21, 2016

    i check for power at the coil key on with a test light i connect the clip to the negative side of battry and the pointed to the tan wire at the coil it show power at the first test but now it show no power on the tan wire at the coil what i need to check to get power at the tan wire again? and then i turn the key off i connect the clip to the positive side of the battry and the pointed to the black wire on the coil it show power why it show power at ground? do it suppose to have power at the wires at the cranksensor with key on?

  • Randy Ohler Dec 21, 2016

    When you test the power wire to the coil it will come on then off. ASD relay. It comes back on when you try to start it. The the PCM keeps it on. When you connect the tester to the positive side of the battery, you are now check for good grounds. You have already determined the crank sensor is bad. Replace it.

  • Joe Russell Dec 22, 2016

    i want to make sure i am understanding what you are saying when i connect the clip end of the test light to the positive side of the battry and the point end of the test light to the ground (black wire) on the coil with the key off and there is power at the coil are you saying that the crank sensor is causing power at the coil ground side or do it suppose to have power at the black wire on the coil? where does the 3 wires that connect to each coils go to? i really do thank you for your help.

  • Randy Ohler Dec 22, 2016

    Yes the light will come on this way. The three wires to the coils are power and ground. You checked them and both are there. The third wire comes from the powertrain control module(PCM/computer). The PCM will not fire the coils without the crank sensor.. You checked it at 7100 ohms. It's bad.

  • Joe Russell Dec 23, 2016

    i bought a new crank sensor and the the resistance on it read 0.75 with meter set on 20k
    resistance read 00.6 with meter set on 200k
    resistance read 000 with meter set on 2000k
    are the new sensor bad to?

  • Randy Ohler Dec 23, 2016

    Could be. Seen it to many times. Not likely though. I would put it in and see. I own my scanners and others at work, I have access to many programs that help me at work. I work on too many models to remember every spec. I try to give the most logical choice. After that. I need it my hands, or you need to take it to a shop for possible PCM problems. I can diagnose sensors, or PCM problems within 1 hour. Wiring takes a bit longer. Sorry, but I have given all the info I can. Your codes go to the throttle body. This doesn't effect the spark. At this point, replace the PCM and have it programmed. This is just a guess though.

  • Joe Russell Dec 23, 2016

    Thanks for the info you did share with me how can i find out the correct ohms spec on the crank sensor?

  • Randy Ohler Dec 23, 2016

    Sometimes I get them threw the programs at work. Most times I check them with a new part. There is 12 ways to check your sensor at the pins. Start with the black lead on the first pin and check the others with the red. Move to the second, then third pin. Swap the leads and use the red on the first pin then second and third. Write down the ohms for all. See how they match. Or just throw the new one in and see what it does.

  • Randy Ohler Dec 23, 2016

    I'm working on a Jeep right now with the same problems. I have checked wiring, replaced the PCM(twice), replaced any sensor I have found to affect it(they checked good), Pulled the wiring harness and went threw it wire by wire. Now I'm getting ready to on the inside and check computers and ignition. Every thing works, Just no spark at the coils.

  • Joe Russell Dec 24, 2016

    my sensor only have 2 wires are you saying i can check it 12 ways i want to know how do i check the trigger side of the crank sensor and the trigger side of the coils? do the 2 wire crank senor have a power side and ground side to? how do i check the ignition switch? please let me know when you find out the problem on the Jeep.

  • Randy Ohler Dec 24, 2016

    Sorry, you told me that. No, just one way to check.

  • Joe Russell Dec 25, 2016

    how do i check the trigger side of the crank sensor and the trigger side of the coils? do the 2 wire crank senor have a power side and ground side to? how do i check the ignition switch? please let me know when you find out the problem on the Jeep thanks for your answers.

  • Randy Ohler Dec 25, 2016

    If your volt meter reads hertz, you can check the crank sensor. Set it to hertz, hook the leads to the sensor, then tap the end or the sensor with a screwdriver or any piece of steal metal. If you see any numbers on the readings while tapping, the sensor is good. With the coil it has to be plugged in. Set it to A/C volts. Probe the negative wire and the signal return wire. Crank the engine. Any numbers, Means the PCM is Working. That would mean all the coils are bad. Unlikely though.

  • Joe Russell Dec 25, 2016

    i don't do my volt meter reads hertz or not how would i know what to look on the meter?

  • Joe Russell Dec 26, 2016

    i don't know do my volt meter reads hertz or not how would i know what to look for on the meter?

  • Joe Russell Dec 26, 2016

    i don't know do my volt meter reads hertz or not would hertz be written on the volt meter?

  • Randy Ohler Dec 26, 2016

    It will have a setting marked htz. Or if auto, you have to hit the button to find it on screen. Low dollar meters don't have it. Mine costs about $300.

  • Joe Russell Dec 26, 2016

    my meter don't have htz on it.

  • Randy Ohler Dec 26, 2016

    Did you ever check continuity of the wires from the crank plug to the PCM? You will need electrical diagrams and pin outs for the plugs to check. I buy mine. Alldatadiy.com

  • Joe Russell Dec 26, 2016

    no i havn't check continuity of the wires from the crank plug to the PCM do this mean i am checking for a broke wire? so i suppose to disconnect the crank plug and the PCM plug? are the PCM located under the hood? Thanks for your help.

  • Randy Ohler Dec 26, 2016

    Yes it does. I care not to buy a program to let you know how to check pin outs. You need this. Everything I do at home costs me. I pass it on the the persons car I am working on. At least you took the next step with electrical. good job. You have two steps left. Call the PCM bad or check wiring.

  • Joe Russell Jan 01, 2017

    you said you had the same problem with the Jeep that i am having with the 2004 GMC Envoy have you found the problem yet on the Jeep? when you do please let me know.

  • Joe Russell Jan 10, 2017

    you said you had the same problem with the Jeep that i am having with the 2004 GMC Envoy have you found the problem yet on the Jeep? when you do please let me know.

  • Randy Ohler Jan 12, 2017

    Still searching on mine joe.

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  • GMC Master
  • 44,486 Answers

Seams that the original problem is that the immobilizer is not operational
it tells the ECM not to allow power to any where on the engine

Posted on Jan 12, 2017

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  • Contributor
  • 6 Answers

Unplugged coil should be plug with two wires make sure there is a ground one wire then when you crank engine the other wire should emit electric pulse you could use a regular test light for that.you need to troubleshoot by eliminating things to find root of problem.I would also check fuses to make sure nothing burnt.I will let you know that if either is gone the crank or camshaft sensor your engine will not run.if you have a vcu gone you won't start either.

Posted on Dec 26, 2016

  • 2 more comments 
  • Joe Russell Dec 26, 2016

    the coils have three wires power,signal,ground do i connect the test light clip end to the ground wire and the probe end of the test light to the signal wire?

  • Joe Russell Dec 27, 2016

    the coils have three wires power,signal,ground do i connect the test light clip end to the ground wire and the probe end of the test light to the signal wire?

  • Joe Russell Dec 27, 2016

    the coils have three wires power,signal,ground do i connect the test light clip end to the ground wire and the probe end of the test light to the signal wire?

  • Joe Russell Dec 27, 2016

    can you send me pictures showing how to test for a signal at the coil using a test light? thank's

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dustyboner
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SOURCE: dead cylinders 2003 sebring

it sounds like you may have the wires on the wrong coil. It should be #1 on the #4 coil, and the #3 wire on the #2 coil. you probably have them backwards so 1 and 3 are firing on the exhaust stroke.
the firing order is 1-3-4-2.
they should be hooked like this.
82c8490.jpg

3ddfc56.jpg

Posted on Jan 24, 2009

  • 1201 Answers

SOURCE: car has no spark or injector pulse(new ecm,crank sensor)

Check the fuse for the injectors, some vehicles have the injectors and coil running on the same circut, at the same time check the fuse for the ignition.

Posted on Jan 30, 2009

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SOURCE: Engine died while driving, cranks but won't start.

not all scanners a created equal. You need to check for trouble codes...............but it must be fixec by now.

Posted on Feb 08, 2009

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SOURCE: Cranking but doesnt start, or intermittently not starting

My car does the same thing...sometimes it wont start....have to turn the key off then when I crank it again it fires right away. Possible that the in tank fuel pump pressure regulator isn't building to the proper pressure. Nissan did post a recall....under warranty *recall* I might add.... there is an updated pump that will cure the problem but since you most likely are out of warranty it will cast $400+ for the part plus labour if you can't install it yourself. Call nissan to verify if your car is affected by referencing your VIN with them. Dave.

Posted on Jul 15, 2009

blueextc3221
  • 15935 Answers

SOURCE: 2001 Chevy Malibu, 89,000 miles, 3.1 engine, won't start

CLICK HERE for the injector schematic.
CLICK HERE for the Ignition schematic.

Since the PCM uses info gatheres from the crank and cam sensors to calculate ignition - and there are no OBD codes - in all likelihood, the PCM itself is bad.

The Ignition Module, also transmits to the PCM.

It appears after all your testing - that the PCM is at fault.

It does not error report on itself (unfortunately).

The ignition timing is controlled by the Powertrain Control Module (PCM). No adjustment is necessary (distributorless ignition) or possible.

Please see the following....

The ignition timing is controlled by the Powertrain Control Module (PCM). No adjustment is necessary or possible.
The engines covered by this manual are equipped with distributorless ignitions, ignition timing is controlled by the Powertrain Control Module (PCM), as applicable. No adjustments are possible. If ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.
Ignition timing is the measurement, in degrees of crankshaft rotation, of the point at which the spark plugs fire in each of the cylinders. It is measured in degrees before or after Top Dead Center (TDC) of the compression stroke.
Ideally, the air/fuel mixture in the cylinder will be ignited by the spark plug just as the piston passes TDC of the compression stroke. If this happens, the piston will be at the beginning of the power stroke just as the compressed and ignited air/fuel mixture forces the piston down and turns the crankshaft. Because it takes a fraction of a second for the spark plug to ignite the mixture in the cylinder, the spark plug must fire a little before the piston reaches TDC. Otherwise, the mixture will not be completely ignited as the piston passes TDC and the full power of the explosion will not be used by the engine.
The timing measurement is given in degrees of crankshaft rotation before the piston reaches TDC (BTDC). If the setting for the ignition timing is 10 BTDC, each spark plug must fire 10 degrees before each piston reaches TDC. This only holds true, however, when the engine is at idle speed. The combustion process must be complete by 23° ATDC to maintain proper engine performance, fuel mileage, and low emissions.
As the engine speed increases, the pistons go faster. The spark plugs have to ignite the fuel even sooner if it is to be completely ignited when the piston reaches TDC. Spark timing changes are accomplished electronically by the engine and ignition control computers.
If the ignition is set too far advanced (BTDC), the ignition and expansion of the fuel in the cylinder will occur too soon and tend to force the piston down while it is still traveling up. This causes pre ignition or -knocking and pinging-. If the ignition spark is set too far retarded, or after TDC (ATDC), the piston will have already started on its way down when the fuel is ignited. The piston will be forced down for only a portion of its travel, resulting in poor engine performance and lack of power.
Timing marks or scales can be found on the rim of the crankshaft pulley and the timing cover. The marks on the pulley correspond to the position of the piston in the No. 1 cylinder. A stroboscopic (dynamic) timing light is hooked onto the No. 1 cylinder spark plug wire (2.2L engine only, on the 2.4L engines, special adapters are needed) . Every time the spark plug fires, the timing light flashes. By aiming the light at the timing marks while the engine is running, the exact position of the piston within the cylinder can be easily read (the flash of light makes the mark on the pulley appear to be standing still). Proper timing is indicated when the mark and scale are in specified alignment.


WARNING When checking timing with the engine running, take care not to get the timing light wires tangled in the fan blades and/or drive belts.

The engines covered by this manual are equipped with distributorless ignitions, ignition timing is controlled by the Powertrain Control Module (PCM), as applicable. No adjustments are possible. If ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.




Thanks for using FixYa!!

Posted on Aug 18, 2009

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Dec 14, 2016 | 2004 GMC Envoy

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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
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Dec 02, 2016 | GMC Cars & Trucks

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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
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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

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