I have a problem with my son's 02 ram 1500 with 3.7L. Truck will not run. If you crank it over for a while it will eventually start with pedal to the floor. When it starts it runs VERY rough and will not idle. We replaced the cam shaft position sensor, checked all coils for spark and replaced plugs. We have retrieved error codes (by turning key on and off and displayed in odometer) the codes all seem to point to ignition and or bad pcm. codes are as follows. p0113, p0340, p0352, p0505, p1491, p1687. The p1687 code has been around for a while. The others are new. kind of looks like need new PCM but don't want to replace it if something is going to kill a new one. Can anyone help guide us in the right direction here? Please!

 

One other thing to add. When we can get it to run, it blows some white smoke out the tail pipe.

 

those codes are mainly circuit malfunction codes, I would check wiring harnesses and around the sensors causing the codes
what does the white exhaust smell like? coolant or carbed up?

 

Have checked all the wiring visually. Also rang out the wires from the sensors to the control module. Checked for continuity and short to ground. all good.
As for the smoke, it smells horrible but it does not smell like coolant. If it smelled like coolant it would lead me down the head gasket path. The oil on the dip stick looks fine but we do plan to check the compression today to verify.

 

This definitely sounds like a bad wiring/connection problem somewhere... For all of those things to go wrong at the same time is very very unlikely unless the truck is really really beat up and not maintained.

I'd start by checking each and every ground connection for corrosion and even remove, clean and reinstall them....

Next thing I'd do is start investigating each and every sensor/item in question and follow the wire all the way back to the PCM checking for wires that have melted and/or insulation that is worn away showing bare wires.

Once you verify that the wiring is 100%, you might try swapping with a PCM from another truck with the same engine... or just buy a new one [pre-programmed] and swap it.

Electrical problems are a nightmare, so just be patient and keep at it.

 

Definitely have some electrical issues. I would not throw a new PCM in there until you are certain there are no shorts.

Double check your cam sensor and the ignition coil since it appears you had serviced these areas and some of the dtcs seem related to these areas.

Make sure your electrical connections are clean by using electrical contact cleaner on all contact points, when possible.

I believe the P1687 is telling you that the PCM is not getting a can bus signal from the instrument cluster. Did you notice if any of the gauges work when you had it running?

The possible issues are:
short between pcm and cluster
open between pcm and cluster
pcm
cluster


Rundown on all your codes:

(M) Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.

P0113 (M) Intake Air Temp Sensor Voltage High-Intake air (charge) temperature sensor input above the maximum acceptable voltage.
P0340 (M) No Cam Signal At PCM-No Fuel Sync
P0352 (M) Ignition Coil # 2 Primary Circuit-Peak primary circuit current not achieved with maximum dwell time.
P0505 (M) Idle Air Control Motor Circuits
P1491 Rad Fan Control Relay Circuit-An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays.
P1687 No MIC BUS Message (No Cluster BUS Message) No CCD/J1850 messages received from the Mechanical Instrument Cluster (MIC) module.

 

I think there are also mechanical issues here. Did compression test on the front 4 cylinders. (1--4) 1=30 psi, 2=185 psi, 3=0 psi, 4=180 psi.
would have to guess head gasket problem??

 

Darn that sucks!

For arguments sake, have you also tried the wet compression test?

 

Wow... that points to some valve problems or you spun some bearings due to oil pump failure or something....

Yeah, It's time to take the heads off and see what's really wrong in there...