Mechanics

MOTOR SWAP

1997 Dodge Ram • 5.9L V8 4WD Automatic • 180,000 miles

I have a 97 dodge ram 1500 it had a 5.2 in it I put a 95 5.9 back in it and the pick up coil and the crank position sensor will not plug in I have the plugs from the 95 they have different colors I need to know how to wire them or I need to know what each wire does
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Dodge on 40s
January 20, 2014.



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.

Caradiodoc
Jan 20, 2014.
My harness has a black with light blue a gray with black and a purple with white I got the pick up coil wiring figured out now I need the crank position figured out

Tiny
Dodge on 40s
Jan 20, 2014.
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.

Caradiodoc
Jan 20, 2014.
Ok hopefully that will fix it I have no fire both of them sensors will keep it from having fire im pretty sure

Tiny
Dodge on 40s
Jan 20, 2014.
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.

Caradiodoc
Jan 20, 2014.
Ok I got them hooked up and still no fire idk what it could be how can I check them sensors

Tiny
Dodge on 40s
Jan 20, 2014.
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.

Caradiodoc
Jan 20, 2014.
How can I test the crank position sensor to see if it is good or not with a power tester

Tiny
Dodge on 40s
Jan 22, 2014.
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.

Caradiodoc
Jan 22, 2014.