So I have had really good luck with my 01 dakota 4.7 QC 2wd. It has never left me stranded, just delayed.
However I have an issue now. It will crank and not start with no engine indication light as soon as I turn it to accessory.
Sometimes it will start and the engine light will be illuminated right away. The check engine light never stays on and no code is stored using the 3 on/off method.
I have replaced the cam position sensor and it would still be intermittent. Replaced the crank sensor with the same outcome. Over the last day it will not start not even intermittently.
So obviously I’m thinking about putting the original parts back in, maybe I induced another problem with the new parts. But what has me concerned is the fact I have had a small evap leak leading up to this problem. Now, the check engine light does not illuminate to indicate any problem when it does run, and no engine indication at all when it won’t start, I thought no communication with the PCM might be the problem.
Has anyone else had this problem? TIA

 

A small evap leak shouldn't cause it not to start. If you didn't use Mopar sensors, return them if you can. Pull off the intake hose going to the throttle body, open the butterfly valve and spray some starter fluid or gasoline into it. If it starts then dies, then you have a fuel delivery problem. You can also check fuel pressure with a rented gauge. Should be free once you return it. How are the plugs? You need fuel, spark and compression for an engine to start and run (well, air too). One of these things is the issue.

 

Went to start the truck the next day. Did not start got the “no bus” message on the odometer. Put the stock crank and cam sensor back in. I don’t own a analog multimeter to test the crank/cam sensors. Still no bus, kept digging….Pulled pcm connectors off found a brown sticky substance in the one closest to the firewall cleaned all the connectors and now it starts intermittently again. The no bus is not indicating anymore. Anyone know the process to isolate the problem as the pcm?
thanks

 

Got a scan tool that will plug in, and talk to the PCM?

The sticky brown stuff might have been what the PCM is potted with.... if that's the case, then it should be considered 'failed', and should be replaced.

 

No I don’t have a scan tool. The 3 on/off cycles Indicate a pdone message. Do you have a recommendation for a brand?

 

Is that stuff coming out around the pins on the PCM?????

May not hurt to clean all three connectors there, and plug 'em in, pull 'em out a few times. See if that improves anything.

Also, I might be tempted to grab another warm body, and press on the PCM connectors while cranking, and see if it will start.

 

I notice that connector is quite dirty on the outside compared to the others. Makes me think that the source is from something dripping or spilled on it. Did you have a mess in the engine bay at some point? I would try using some electronic cleaner to get that out. Make sure to spray inside the connector as well. Let it dry then test. If some of the pins are shorted out from that oil it could cause all sorts of crazy.

 

Heyyou- I’m unsure where that substance is coming from. I am not the car wizard so I did not taste it but it was sticky like soda syrup. Cleaned it up agin tonight just a trace amount inside.

so today it started everytime I tired it maybe 6 times. No check engine light no error code. So I got a little brave and went about half a mile came back home and parked died idling within a minute of being home. Restart it runs for 20 secs. Restart again dies within 50 seconds. Go to restart again “no bus”comes up on the odometer I grab my meter leave the key in the on position. Go to check for 5v at the IAC as it the easiest to get to. 5v is present plug it back in check engine light p0123 is what it is reading on the 3x on off which is related to the IAC.


Not only intermittent but is also affected by heat. I suppose I’ll just order up a refurbished pcm. Anyone have any recommendations?

 

This unit has had a software update at some point in its life as it has a decal over the original.It does seem like it was soda that was spilled on it, and must have seeped in 🤷‍♂️

I’ve owned the truck about 5 1/2 years bought it from the original owners grandson who drove it about a year before selling it. Truck just turned over 98k other than all new control arms and inner and outer tie rods last year this thing has just had standard maintenance done to it.

 

IAC should operate at 12 volts...... on two wires. TPS, and temp sensors are 5 volt.