I have a 2000 dakota with 3.9 manual. It has 261000 miles approx on it. I can't figure out why it wont start. Here is the story: I have 47 lbs of fuel at the fuel rail. no spark. no power to my coil, cam ( hall effect sensor ) or crank sensor. ran great up until about 2 weeks ago. All of a sudden started to start hard, by that i mean turn over for a good 30 seconds or better to fire up. not turning over slowly either good fast cranks. when it fired it ran great. just went out to start it this morning and wouldn't. I originally thought the fuel pump was losing its prime, so i put a pressure gauge on there a few days ago and before i started it i looked and it was still upwards of 45 lbs only dropping 2 - 5 lbs overnight. but back to the original question. No spark. If it was in asd mode would i still have the fuel pump run and no spark or would it all be cut off? Should i still have power ( I have the 5v reference power but not the 12v ) to the cam and crank? I am lost


Thanks for your incite and ideas.

 

I am not 100% sure but I think if the ASD relay is bad it cuts power to the coil and the cam and cranks sensors. See if you have an ASD relay in the power distribution center, it might be labeled O2 or oxygen sensor relay. Either swap in a relay you don't need for the test like the horn relay or just get a new relay at the parts store and see if it starts then.

I might be wrong but this sounds like an ASD problem to me. Others here will probably have better info for you.

Jimmy

 

I appreciate that, i already tried it though. I actually used my fuel pump relay had same part numbers on it. I swapped them and the same thing, fuel pump runs and no spark. How and what do i have to do to determine a bad pcm, cam or crank sensor? If it is a pcm and I use a pcm out of a automatic just to see if it will fire? The reason I ask is that i have another dakota that i can use for parts but it is a automatic. thanks again

 

I agree with 01SilverCC sounds like ASD relay but could be bad coil.

check coil by

to check the wires giving battery voltage disconnect the coil electrical connector check for battery voltage on the dark green/orange terminal wire with the key on. if no battery voltage then it is the automatic shutdown relay.

to check to see if the coil is getting signal to fire. take a test light and back probe the coil driver terminal (black/gray wire). make sure test light has a good ground.
have a fried you trust crank the engine (make sure trans in neutral, clutch is pressed in, and park brake is on, hair, clothing, ect is out the way of moving parts ), and the test light should light every time the coil is told to fire. if not its not getting signal from PCM and the camshaft position sensor and crankshaft sensor needs to be checked.

remember to take all precautions to be safe.

KillerKilgore

 

Thanks, I did everything you said......... got ground at coil, got not power. Either when key is switched on or cranking. Correct me if i am wrong but if the asd was in effect wouldn't my fuel pump be cut off during and after cranking? It would only initially fire up for about 2 seconds prior to cranking right? I have power initially, and while cranking to the fuel pump. It is a consistant 47 lbs. I am wondering if there is a way with a ohm meter to check the crank, cam sensor? Also what one comes first int he series? When i unplug my crank sensor i get no fuel pump, so does that mean my crank sensor is good and the cam is bad? How would i go about testing the computer to see if it is good other than my snapon solus? I can communicate fine with computer. thanks and sorry for so many questions.

 

bad ASD relay



have been told once the pressure is up to where it should be the fuel pump will cut off until the computer was told that the coil has fired.

ohmmeter no. voltmeter yes. it will set error code in PCM so be sure to clear codes. need analog voltmeter

check if crank sensor getting signal
put voltmeter on 12 volt DC connect positive side of meter to terminal 3 of wire harness of crank sensor and negative side of meter to no.2 terminal of wire harness. should have +- 5.0 volts.
to see if crank sensor is sending data

reconnect wiring harness, backprobe positive voltmeter wire to no.1 on crank sensor harness and the negative to a good engine ground. turn key on and rotate engine slowly with breaker bar. voltmeter should bounce between 0 and 5.0 volts as notches on flywheel pass sensor.

camshaft position is a lot more detailed recommend getting haynes manual.
goto chapter 6 it tells all about pages 14 and 15
don't know i would think it is not 1 or the other but both.

if the part number on the computers are the same then it should b e OK to switch them out.
also found out that the PCM uses coolant temp sensor and TPS to adjust fuel and ignition timing.

hope this helps

KillerKilgore

 

does my truck year fall into the category of the bad splice under the fuse box? or is that the first generations only?

 

I hope i am not stepping ahead of myself but I believe i figured it out tonight. After many hours of chasing wires and going through alldata schematics i found a oxygen sensor that was grounding itself out, and when i unplugged it i started receiving power and my pulsating ground. However my coil does not work, i believe my oxygen sensor shorted out and was sending feedback through the computer and lead to my coil being shorted out. I will find out for sure tomorrow when i order up a new coil and oxygen sensor. I will keep you posted. thanks for the incite.

 

good to know about the O2 sensor I will have to remember that.
now i have to figure out what to forget so i can remember this info.
hope everything works

 

Yup believe it or not that is what it was! I put a new coil on it and left the oxygen sensors unplugged fires right up! I plug the oxygen sensors in and no fire!!!! Well shes running again without oxygen sensors but i will put those in tomorrow. thanks for your answers.