Jeep Cherokee 4. 0 - Crank / No Start
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Date: 2020-08-05
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Comments and reviews: 10
Ple
There is also the case when the crank sensor functions well and the car has no problems until the engine fully warms up. That is the time the car shuts off and will crank but not start until it cools down. That is a bad sensor case too. What I believe is happening is that it is thermally sensitive to temp cycling. A crank sensor has coils inside around a magnet. Coils are being stretched when hot, then contracted when cold. They might have small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and stop the coils ability to function.
It is common to misidentify a crank fault with a cam fault and vise versa. Therefore a P0340 code could be a crank sensor or a cam sensor fault. But a P0320 is the classic crank sensor code. If you have a digital scope you can test these sensors one by one. Generally, on Chryslers (many different models) the wiring for the cam and crank sensors is:
The middle wire (Black/blue or DkBlue/DkGreen) is sensor ground.
The (Violet/Red or Yellow/Pink) is 5V reference = the 5V power feed. It is the right wire when you look at it with the locking tab on the top.
The (Tan/Yellow or DkBlue/Gray) is the cam 5V signal. It is the left wire when you look at it with the locking tab on the top.
Disconnect the sensor harness and check these 3 wires (front probe on the connector) with a multimeter one at a time with the key in ON position to see the integrity of the harness. You should be getting zero volts in the middle and 5 volts on the other two sides. If you do, that means the PCM and the wire harness is okay up to the sensor. Then, connect the sensor to the harness (can be on or out of the engine) and back probe it and if you get less than 5V on the signal wire, that means it is a shorted crank sensor. Using a ferrous material such as a thick wrench or pry bar or chisel near it and far from it you can test its transistor switch (by electromagnetism) in relation to voltage. Measure voltage on its signal wire. It should be 5V when the ferrous material is far from it and when you touch the ferrous material on the front of the sensor the voltage should be dropping to zero. It will be pulling the signal low as it goes closer.
---Regarding the ground wire to have a fault is slim to none. Same as the 5V reference. The ground wire should be zero or near zero before cranking and we are looking for a 0. 1V or 0. 2V during cranking.
---The 5V reference should be 5V steady power feed before cranking and after cranking.
---The signal wire like I said before should show 5V before cranking and if it doesn't, that means the sensor is bad. If you do get 5V it doesn't necessarily mean the sensor is good until you check the signal during cranking too. The signal wire from near 5V before cranking should be having a square wave between 5V & 0V during cranking. If you don't see the alternating 5V to 0V to 5V and so on, it means the sensor is bad. Use the scope to about half a second time base to see the graph.
Another way to test which sensor is bad (instead of testing individual sensors) is by using a high end scanner such as the Verus Edge and select it to display Camshaft Counts (CMP COUNT) and Crankshaft Counts (CKP COUNT) during cranking.
And don't forget the case i mentioned first when the crank sensor functions well and the car has no problems until the engine fully warms up. First paragraph.
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There is also the case when the crank sensor functions well and the car has no problems until the engine fully warms up. That is the time the car shuts off and will crank but not start until it cools down. That is a bad sensor case too. What I believe is happening is that it is thermally sensitive to temp cycling. A crank sensor has coils inside around a magnet. Coils are being stretched when hot, then contracted when cold. They might have small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and stop the coils ability to function.
It is common to misidentify a crank fault with a cam fault and vise versa. Therefore a P0340 code could be a crank sensor or a cam sensor fault. But a P0320 is the classic crank sensor code. If you have a digital scope you can test these sensors one by one. Generally, on Chryslers (many different models) the wiring for the cam and crank sensors is:
The middle wire (Black/blue or DkBlue/DkGreen) is sensor ground.
The (Violet/Red or Yellow/Pink) is 5V reference = the 5V power feed. It is the right wire when you look at it with the locking tab on the top.
The (Tan/Yellow or DkBlue/Gray) is the cam 5V signal. It is the left wire when you look at it with the locking tab on the top.
Disconnect the sensor harness and check these 3 wires (front probe on the connector) with a multimeter one at a time with the key in ON position to see the integrity of the harness. You should be getting zero volts in the middle and 5 volts on the other two sides. If you do, that means the PCM and the wire harness is okay up to the sensor. Then, connect the sensor to the harness (can be on or out of the engine) and back probe it and if you get less than 5V on the signal wire, that means it is a shorted crank sensor. Using a ferrous material such as a thick wrench or pry bar or chisel near it and far from it you can test its transistor switch (by electromagnetism) in relation to voltage. Measure voltage on its signal wire. It should be 5V when the ferrous material is far from it and when you touch the ferrous material on the front of the sensor the voltage should be dropping to zero. It will be pulling the signal low as it goes closer.
---Regarding the ground wire to have a fault is slim to none. Same as the 5V reference. The ground wire should be zero or near zero before cranking and we are looking for a 0. 1V or 0. 2V during cranking.
---The 5V reference should be 5V steady power feed before cranking and after cranking.
---The signal wire like I said before should show 5V before cranking and if it doesn't, that means the sensor is bad. If you do get 5V it doesn't necessarily mean the sensor is good until you check the signal during cranking too. The signal wire from near 5V before cranking should be having a square wave between 5V & 0V during cranking. If you don't see the alternating 5V to 0V to 5V and so on, it means the sensor is bad. Use the scope to about half a second time base to see the graph.
Another way to test which sensor is bad (instead of testing individual sensors) is by using a high end scanner such as the Verus Edge and select it to display Camshaft Counts (CMP COUNT) and Crankshaft Counts (CKP COUNT) during cranking.
And don't forget the case i mentioned first when the crank sensor functions well and the car has no problems until the engine fully warms up. First paragraph.
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tempest411
Aftermarket parts in general just suck, but as long as the American consumer expects caviar at tuna fish prices, they're going to continue to be served pure crap. The auto parts industry needs to be REGULATED. Manufactures must PROVE the parts they make are as good as the OEM and receive certification stating as much before the part can be sold. The free market does not work in this case because customers are IDIOTS. Did you know I could saw up some wood blocks into the shape of brake pads and sell them as. brake pads and it would be perfectly legal?
The above rant was brought to you by 31 years of auto parts experience.
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Aftermarket parts in general just suck, but as long as the American consumer expects caviar at tuna fish prices, they're going to continue to be served pure crap. The auto parts industry needs to be REGULATED. Manufactures must PROVE the parts they make are as good as the OEM and receive certification stating as much before the part can be sold. The free market does not work in this case because customers are IDIOTS. Did you know I could saw up some wood blocks into the shape of brake pads and sell them as. brake pads and it would be perfectly legal?
The above rant was brought to you by 31 years of auto parts experience.
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Dencil
Just look at a pre defeated japanese woman and her children the same with germany and china and look at all the children born after the end of the war after those young American boys turn lose on those women mix breeds by the thousands beautiful children the same with veitnam
there is almost nothing made today that is not made in CHINA i have seen chinese / bahamian MAN those damn gals look gooooood and the speak Bahamianese too
i e lieing ya gat dat
Bahamianese
all the way from beautiful
nassau, bahamas
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Just look at a pre defeated japanese woman and her children the same with germany and china and look at all the children born after the end of the war after those young American boys turn lose on those women mix breeds by the thousands beautiful children the same with veitnam
there is almost nothing made today that is not made in CHINA i have seen chinese / bahamian MAN those damn gals look gooooood and the speak Bahamianese too
i e lieing ya gat dat
Bahamianese
all the way from beautiful
nassau, bahamas
reply
Ken
I have been having this intermittent crank but no start condition behaving similar to this jeep over the past year. One mechanic replaced the fuel pump, which seemed to fix the issue for about a month until I have stranded again, then it was the TIPM (fuse box, but even with that it still acts up from time to time. The truck is not giving up any codes, but when it acts up, shows symptoms just like this. Since cam and crank sensors are relatively cheap, I am tempted to just replace them. Would this be a good idea.
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I have been having this intermittent crank but no start condition behaving similar to this jeep over the past year. One mechanic replaced the fuel pump, which seemed to fix the issue for about a month until I have stranded again, then it was the TIPM (fuse box, but even with that it still acts up from time to time. The truck is not giving up any codes, but when it acts up, shows symptoms just like this. Since cam and crank sensors are relatively cheap, I am tempted to just replace them. Would this be a good idea.
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Jesse
Hi I am in need of help I have a 2004 jeep grand cherokee laredo 4. 0 was having starting issues and dieing out one day with death shake. Believe it was fuel pump. Replaced it workd for a day and half. Then started no crank no start up thing so followed that path with crank sensor started cranking but no start replaced asd relay same issue still. Replaced started same issue. Replaced cam sensor same issue. had friend helping today did see that fuel pressure is good. Just cranks and cranks still.
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Hi I am in need of help I have a 2004 jeep grand cherokee laredo 4. 0 was having starting issues and dieing out one day with death shake. Believe it was fuel pump. Replaced it workd for a day and half. Then started no crank no start up thing so followed that path with crank sensor started cranking but no start replaced asd relay same issue still. Replaced started same issue. Replaced cam sensor same issue. had friend helping today did see that fuel pressure is good. Just cranks and cranks still.
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Albert
I'm working on a 2006 5. 7 grand Cherokee and with key on engine off every relay starts clicking like crazy and the engine will not crank when I pull the ASD relay out all they clicking stops and if i pull the first connector out of the pcm all the clicking stops as well its also intermittent all day today relays been clicking and no start but yesterday started every time no issues and of course no codes are appearing to give me direction any clue where I should start im so lost
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I'm working on a 2006 5. 7 grand Cherokee and with key on engine off every relay starts clicking like crazy and the engine will not crank when I pull the ASD relay out all they clicking stops and if i pull the first connector out of the pcm all the clicking stops as well its also intermittent all day today relays been clicking and no start but yesterday started every time no issues and of course no codes are appearing to give me direction any clue where I should start im so lost
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AL
Eric Just change engine after 3 pistons failed. I tested Crank sensor Just like you did, and it tested out. power on both leads unplugged and back probed. Still no start. No voltage at Coil, Just tested injectors (no power) did compression test all 6 cylinders 150+. When testing wires from PCM to Power distribution box, dumb luck plugging in 1 PCM wire harness the ASD relay clicked, Yea start it up. Crap NOPE no start. Do we need a new PCM?
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Eric Just change engine after 3 pistons failed. I tested Crank sensor Just like you did, and it tested out. power on both leads unplugged and back probed. Still no start. No voltage at Coil, Just tested injectors (no power) did compression test all 6 cylinders 150+. When testing wires from PCM to Power distribution box, dumb luck plugging in 1 PCM wire harness the ASD relay clicked, Yea start it up. Crap NOPE no start. Do we need a new PCM?
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ShyRage1
You mentioned in the beginning of the video, the security light is not blinking. What was the fix for those particular problems? My jeep has intermittent start issues from time to time and that's exactly what happens when it doesn't want to start. I'll add that when security light blinks I hear a buzzing noise. The starter is brand new though with everything connected properly
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You mentioned in the beginning of the video, the security light is not blinking. What was the fix for those particular problems? My jeep has intermittent start issues from time to time and that's exactly what happens when it doesn't want to start. I'll add that when security light blinks I hear a buzzing noise. The starter is brand new though with everything connected properly
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Carlos
Mine4. 0 grand cherokee work like babe after 5 years. 1 day start and shut off them I put cam and crankshaft sensor new computer and same things. I quit never find the problem 3 month ago no idea I bring to mechanic shop and this people no fix problems no good mechanic in ct.
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Mine4. 0 grand cherokee work like babe after 5 years. 1 day start and shut off them I put cam and crankshaft sensor new computer and same things. I quit never find the problem 3 month ago no idea I bring to mechanic shop and this people no fix problems no good mechanic in ct.
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freakingnewguy
Hey I hope someone can help me I have 96 grand Cherokee with the 4. 0 in it and I'm not getting spark and the fuel pump stays on and the fuel and battery guage do not come one when I put the key into the on position
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Hey I hope someone can help me I have 96 grand Cherokee with the 4. 0 in it and I'm not getting spark and the fuel pump stays on and the fuel and battery guage do not come one when I put the key into the on position
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