1997 Dodge Ram motor swap

Both sensors share a common ground wire, usually a black / light blue, and they share a 5.0 volt feed wire. They each have their own signal wire.

Well, you have a '97 truck with a '95 engine, and all I can find is a '96 service manual. Fortunately Chrysler has been real good about parts interchangeability and using the same wire colors over many years.

I show a black / light blue for the ground wire for both sensors. A violet / white is the 5.0 volt supply for both of them. The signal wire for the camshaft position sensor is tan / yellow. For the crank sensor it's gray / black. You may find different colors on the sensor pigtails. If you need to know the locations of those wires in the connector, I can try to describe them. The ground wire is in the middle on both of them.

Yup. The Engine Computer needs to see the signals from both sensors to tell when the engine is rotating. That's when it turns on the automatic shutdown (ASD) relay. That relay sends current to the ignition coil, injectors, alternator field, oxygen sensor heaters, and fuel pump or pump relay.

You need an oscilloscope, a Chrysler DRB3 scanner, or an aftermarket scanner that will display live data. Both sensors will be listed as "present" or "no" during engine cranking.

The first test is to measure the voltage to the ignition coil or any injector. You will see 12 volts there for one second after turning on the ignition switch. Test lights work better than digital voltmeters because most voltmeters don't respond fast enough. If you have 12 volts for that first one second, see if it comes back during engine cranking. If it does not, that's when we need to look at the two sensors.

What's a "power tester"? The definitive test is to view live data on a scanner. That will tell you in an instant if the sensor has 5.0 volts and ground, is generating a signal, and it's reaching the computer. You can view the waveform on an oscilloscope too. Being in tv repair for decades, I have many "scopes", but I never tried using one on a car. Some people try to use a digital voltmeter but those results are useless. Most digital meters don't respond nearly fast enough to such rapidly-changing signals, and there is no range that works for this type of signal. The voltmeter takes a voltage reading, analyzes it, then displays it while it takes the next reading. The waveform is a square wave pulse that is close to either 0.0 volts or 5.0 volts, like switching a light on and off. The voltage display on the DC range will be bouncing around and will be impossible to read. On the AC scale the meters are designed to measure a smoothly-changing sine wave at 60 hertz, not an intermittent square wave.

Some mechanics have digital meters that can measure the frequency of a square wave. That applies to mass air flow sensors on Fords where, as usual, they do things differently than everyone else, but that is a steady square wave. The signal from a crank or cam sensor is not steady. This varies from year to year and between engine sizes, but in general, once per crankshaft revolution, there will be a series of three square wave pulses coinciding with three holes on the flex plate, then nothing until the crank turns a quarter turn, then three more pulses, then nothing, then three pulses again, then nothing, then four pulses. The Engine Computer knows when number one cylinder is coming up to top dead center by the series of four pulses, only two pulses, or in some cases by the different sequence of pulses from the cam sensor. When you switched the engine, did you check if the flex plate had the same cutouts? If you reused the flex plate the truck came with, that is not an issue. If you used the flex plate that came with a different engine and the notches are different, the Engine Computer won't recognize them and it won't know when to fire the ignition coil. The firing order is not important to the computer when the engine uses a distributor to select the right spark plug to fire, but if the wrong series of pulses shows up from the crank sensor, the computer may not turn on the ASD relay, even though both sets of sensor signals are present.

When it comes to computer-controlled engines, it is never a good idea to switch to a different size, and you can also run into a lot of problems when switching between different years, even of the same size. In particular, to keep up with constantly changing emissions laws, the notches on the flex plates will be different in different years. They fit and bolt up the same, but the numbers of those notches are different. A signal pulse is developed for each notch. Those tell the Engine Computer when a piston is coming up on top dead center, and some tell the computer when piston number one is coming up on TDC. The computer counts those signal pulses, and it can take a few engine revolutions before it figures out when piston number one is on TDC on the compression stroke. From then on it calculates which injectors and which ignition coils to fire each time it receives a series of pulses.

For some V-8 engines, there will be four pulses, a gap, then four pulses, another gap, four more pulses, another gap, then three pulses. Some have four sets of four pulses. The Engine Computer will only accept the series of pulses it is programmed to expect.

When you had a V-6 engine, that Engine Computer expected to see three groups of signal pulses, not four, so the computers don't interchange. Much of the wiring harnesses will be the same, but with different numbers of injectors and ignition coils, there are going to be some major differences.. Even worse, when you're going from one engine size to another, the transplanted Engine Computer may be expecting to receive data from the other computers, some of which aren't on your truck. The Engine Computer may not send some data the other computers need. We see that most often when the Body Computer or the instrument cluster don't communicate properly. That can leave you with things like dead dash gauges, warning lights always turning on or never turning on, and computers setting erroneous diagnostic fault codes. Stored fault codes can cause computers to suspend many of the self-tests they constantly run, so new problems could develop, and you'll never get a new fault code to direct you to the circuit or system that needs further diagnosis. With no fault code to get you started, you may never be able to figure out where to start looking for the cause of some problems.

You said your truck doesn't run, but you didn't say if this is a new or recent problem or if it has been since the new engine was installed. If it has never run with the new engine you have a real lot of work ahead of you. It would make more economic sense to put the right engine in it or look at this as an opportunity to buy the truck you want.

If this is a new problem with an engine that had been running in this modification, we should start with reading and recording the diagnostic fault codes. You can go here:

https://www.2carpros.com/articles/retrieve-trouble-codes-for-chrysler-dodge-plymouth-odb1-1995-and-earlier-car-mini-van-and-light-trucks

for instructions, but there are some differences. Chrysler made reading fault codes yourself much easier than any other manufacturer. Instead of cycling the ignition switch five times, while that will get it done, you only have to do that three times within five seconds.. Next, instead of counting flashes of the Check Engine light, on '96 and newer models the code numbers will show up in the odometer display. You can go here:

https://www.2carpros.com/trouble_codes/obd2/p0400

to see the definitions, or I can interpret them for you.

I am happy to continue our conversation here, but you should really consider starting a new question specific to your truck. Unlike other sites where anyone can chime in to confuse the issue, here this became a private conversation between just two, and sometimes three people. It is only us who get notified when a reply has been posted. As such, none of the other experts are going to see your addition or have a chance to reply. That may not get you the help you need. If you do start a new question, please be sure to list the mileage, transmission type, and repeat the engine sizes. Also include the history that led up to the current problem. We look at all of that when making generalizations as to best suspects for causes of problems.

You can't run a V-8 engine with a computer for a V-6. Even if the number of cutouts is the same for each group on the crankshaft position sensor's tone ring, you'll be getting four sets of signal pulses per crankshaft revolution, but the computer counts one revolution as every three sets of pulses. There's also eight injectors now, each requiring its own driver circuit inside the computer, but the old computer only has six driver circuits. There's nothing to fire two of injectors.

As for the transmission, in the past, Chrysler had three bell housing patterns, one for the slant six cylinder engines, one for the small block V-8s, (273, 318, 340, and 360), and one for the big blocks, (361, 383, 400, 426s, and 440). That changed when they came out with the 3.9L V-6. That is a 318 with two cylinders chopped off, so the front and rear of the block is the same as the 360 you put in.

Next, within each bolt pattern style, there were two sizes of transmission, the smaller "904" and the really tough "727" Almost every big block engine came with a 727 transmission, and most six-cylinders came with the smaller 904. Taxis did come with a 727 if they had the six cylinder engine. Those 727s are real hard to find and are quite desirable for people building hot rods. It's the small block engines that could be found with either transmission, but chances are your truck has the smaller 904 since it came with a V-6. Now you're expecting it to hold up to a 360, (5.9L). It probably will.

Within all of those transmissions I described, there were also "built-up" or stronger versions for some applications. A 360 would typically come with a 727, especially if it was a four-wheel-drive, but it could have also come with a 904 that had heavy duty modifications. As is common with all Chrysler products, many parts interchange, and that includes parts that are common to both transmissions. If your truck does have the smaller 904, a 727 can be bolted in and will mount the same and the shifter linkage will be the same. The way to tell which one you have is to look at the shape of the pan. I posted a photo for you showing the two pans. The smaller 904 is on the left. It's basically a square with one corner cut off. The 727 on the right has a that extra hump that my callout is pointing to. That's on the front passenger-side corner. If you find that you have a 727, that transmission will hold up to diesel engines, so it will definitely hold up to your 5.9L.