2002 Dodge Ram 4.7 Faulty Crank Sensor

Dodge Crank Sensor Issue

Engine stall out at stop signs and red lights

United States 2002 Dodge Ram

Dodge PCM and Wiring Issue
Engine speed circuit malfunction
Speed input circuit malfunction
OBD Code P0320 & OBD Code P0725 On Dodge Ram
O2 Sensor issue on Dodge

Q: 2002 Dodge Ram 4.7, wires near the exhaust got hot and melted and set off the P0320 Code (engine speed circuit malfunction) and P0725 (Speed input circuit malfunction).Fixed the wires and problem solved. Last week this started again with the same codes. Now the wires look fine and the engine likes to stall out at stop signs and red lights. Then it wont start unless I unhook the battery for a minute and then it will start right up. All three O2 sensors error codes came up which is almost impossible that they all go bad at once. When unhook the battery it resets the PCM however; the light does not go off. Would I need a new crank speed sensor ? The wires go to a sensor in the side of the transmission. Could that sensor be bad?


A: There are few possibilities to be checked and confirmed.

Replace Crank Sensor

OBD codes P0320 and P0725 is coming up and the wiring for the exhaust is ok then almost surely you have a bad crank sensor. It's not uncommon for the crank sensor to fail this way and produce an intermittent signal, causing these codes and symptoms.
Crankshaft sensor it is located on the lower part of the engine just behind the harmonic balancer

Dodge Crank Sensor:

Oxygen Sensor

It is unlikely that multiple oxygen sensors would fail at exactly the same time. If the codes started to set at exactly the same time as the crank sensor issue then I would recommend repairing that first and see if maybe the oxygen sensor codes don't come back. It's unlikely that the problem is related but possible. It's possible that you have a wiring, sensor, or PCM problem, but it's unlikely that all three sensors would fail at the same time, if in fact all three codes had set at the same time.

Start with repairing the crank sensor issue, clear the codes and see what comes back before going much further with the oxygen sensor problem.


Transmission Sensor

The sensor on the right rear of the transmission is the line pressure sensor, it's not related to this issue.


Wire schematic of the crank sensor circuit

There are 3 wires.

1. The signal wire is gray/black, it goes from pin 1 of the sensor connector to pin 8 of PCM connector 1. PCM connector 1 is the solid black connector.
2. The sensor ground is the black/light blue wire in pin 2 of the sensor and it goes to PCM connector 1, pin 4.
3. The 5v supply wire is orange and runs from pin 3 at the sensor to PCM connector 1 pin 17.

Please Note: The crank sensor doesn't connect to the transmission speed sensors, the speed sensors are dedicated two wire circuits to the transmission control module.

This will help.

Thanks.

Chrysler eclipse Stalls & Stops At Idle Randomly

Stalling At Idle Issues

97 eclipse manual 420A non-turbo motor stalls and stops at idle randomly, it always starts right back up. Sometimes won't start on 1st try then immediately starts on 2nd. Also jerks or bucks while driving but not all the time. If cruise is on it will jerk & cut off. Reminds me of an automatic trying to climb hill & can't decide to gear up or down rpms remain the same while this happens.


Troubleshooting Possibilities For This Problem:

First of all there are many possibilities that can cause this types of problem.But as per the problem described most of the common possibilities are ruled out.To confirm the problem for remaining possibility,its suggested to get vehicle engine control module scanned with scan tool.
You may end up having to monitor data on a scan tool at the time it acts up to be able to see what is happening.


It can be the Sensor Problem:

One thing I see you haven't replaced is the cam sensor. For your vehicle engine model the cam sensor mounts to the left end of the cylinder head and runs off the intake cam. If the cam sensor signal drops out it will cause the problems you are having, but it would usually set a code.


Crank sensor or Cam sensor Shorting:

One thing that isn't uncommon on these engines is an internally shorted cam or crank sensor taking out the opposite sensor. They both share an 8v reference circuit that they need to be able to produce a signal. If one sensor or the other internally shorts the sensor ground to the 8v reference then it will drag the reference down and prevent both the cam and crank sensors from producing a signal.


No Sensor Reference Signal To PCM:
No Error Code Set But Still A Faulty sensor:

A cam or crank sensor code will set if the PCM sees a signal from one sensor but not the other, it knows the engine is turning if it sees one sensor. If one of them shorts internally and takes down both signals then a code can't set even though one sensor is bad. If your cam sensor is shorting internally that explains the symptoms but lack of codes.


Possibilities To Try:
I recommend to get engine module scanned.But if no scan tool is available I would recommend replacing the cam sensor with a factory part (aftermarket sensors are known to cause many issues).


Jerking and Bucking while driving at High Speeds:

The same problem of faulty sensor or no signal for any of sensor  is causing both the jerking and bucking while driving at higher speeds, but since the engine is turning faster at those times it doesn't die like it does at idle or low speed.

Also It can be Faulty PCM:

It's possible that the powertrain control module (PCM) could be causing this or it could be a wiring issue but these possibilities are less likely than a cam sensor failure. Replacing the PCM would be a last resort if all else can be ruled out.


This details will help.
Thanks.