Dodge Repair Questions? Ask a Mechanic for Answers ASAP
Hello and welcome!
Do you have a scan tool that can read data?
Are there any fault codes in the system.
The most common causes for this concern is a failed crankshaft position sensor. While cranking the engine you should have a rpm reading. It is somewhat common for the pcm to fail also, a no buss message will be displayed in the cluster and the check engine light will not turn on when cycling the key.
Did you install a OEM crankshaft sensor? Aftermarket sensors are know for failure even if they are new.
The pcm ground each coil individuality to control spark.
what engine is in your truck?
Check the year of the engine. The VIN is on the right hand side of the block just ahead of the motor mount.
10th digit in the VIN
There is a early/ late design crankshaft position sensor tone rings that can cause a no start. They should be checked to match up
The Crankshaft Position sensor is mounted into the right rear side of the cylinder block. It is positioned and bolted into a machined hole.Engine speed and crankshaft position are provided through the crankshaft position sensor. The sensor generates pulses that are the input sent to the powertrain control module. The PCM interprets the sensor input to determine the crankshaft position. The PCM then uses this position, along with other inputs, to determine injector sequence and ignition timing.
a tonewheel is bolted to the engine crankshaft. This tonewheel has sets of notches at its outer edge.The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the PCM.
If the engine is a 02 it could have the wrong style tone ring as this was a cross over year, and the correct year of engine will need to be installed. Do you know how many connectors the pcm had going to it on the vehicle the engine came out of?
If the engine is the same year, 10th digit on the both engine blocks are the same you should be ok there. If the engine installed is from a Durango it could be the split year.
The Camshaft Position Sensor on this engine is bolted to the right-front side of the right cylinder head.The CMP sensor on this contains a hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects notches located on a tonewheel. The tone-wheel is located at the front of the camshaft for the right cylinder head. As the tonewheel rotates, the notches pass through the sync signal generator. The pattern of the notches (viewed counter-clockwise from front of engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2 notches 1 notch, 3 notches and 1 notch. The signal from the CMP sensor is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.
No problem at all, Thank You!
A failed ECM, No ckp signal, if there is no cmp the engine should still start but will have a long crank time.
Also injector pulse should be checked this will verify proper operation of the ecm and ckp.
A security system or theft light on could cause the concern.
Did the old engine run before the swap was done?
do you have a test light to check for injector pulse. Or a Noid light can be used. The only problem that can really cause this is a missing ckp signal to the pcm, if the engine did run its likely not a pcm failure.
Try installing the ckp from the old engine, you will need to remove the starter to gain access.
A theft light would be illuminated in the dash and the engine should start up for a few seconds and die with a fault in the security system.
And if the wiring harness was not damaged in the engine swap and installed correctly a wire harness problem is not very likely, a fault code should show up on the scan tool if a wire was open or shorted.
I would start with the ckp this is a easy part to change.
Yes the easiest way is to remove the starter, the sensor is hidden between the engine block and the starter.
By looking at the picture it looks like you wont have to remove the starter and it does not mention it in the service manual. Just be aware i normally have to take the starter out on the 4.7l .
I could be wrong on having to remove the starter but i hope the picture helps out.
not always if the signal is weak or erratic it may not set a code. If the signal circuit was shorted to ground or power yes. Testing the CKP signal with a oscilloscope is the best way to do this.
P1391 is a Intermittent loss of cmp or ckp. This is the code that should set if the engine installed is the wrong year.
or a wiring or sensor fault
what type of scan tool are you using? not all aftermarket scan tools can read all of the codes stored in the pcm.
and 95% of the time a problem with the ckp is the cause for no spark, and no injector pulse.
But the only way to know for sure is to perform the proper tests, and have the tools to do this. I can not guarantee that replacing the ckp is your silver bullet, but at this point it is the best chance you have to getting your truck running. I am here to help i am sorry this is frustrating diagnosing electrical faults can be very difficult for any technician. I am just trying to give you the most information that i can.
Not a problem, if you need help with any tests or anything at all please let me know. A test light is a cheap tool and can be used to check signal to the injectors.
I am going to call it a night i will be back on tomorrow to follow up with any other questions.
Hi! any luck with getting your truck running?
what does the plug go to? On your year of truck wiring faults do not always set a code repair the wires and re test.
i am sorry to hear that, Does the check engine light turn on when you cycle the key?
I am thinking you have the wrong engine installed for your truck with the old style crankshaft position sensor tone ring. this will not set codes and cause a no start condition.
Yes If the replacement engine had a 3 connector ecm then it will not work with your truck. The 4 connector ecm uses a different tone ring, this is the cause for your no start i have seen this before.
I would not recommend trying to swap the crankshafts as the bearing clearances of the crank could be different. With the time and labor to swap the parts would be more then just finding and installing the correct engine. For a long term repair i would just find the correct engine and sell the one that does not work.
The pcm is a updated design and has different software and the pins and connectors will not be the same.
You might get it to work by replacing the engine wire harness but then you run into software issues and security system faults. And the other ECM will likely not be compatible with the other modules in the vehicle.
I have a good friend that is a dodge expert and aftermarket changes i will ask him what he thinks.