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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Car
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Experience:  Associates Degree
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Dodge dakota 6 cyl 22 gal tank: Long story. 96 dodge Dakota

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Long story. 96 dodge Dakota had no spark two years ago. online technician helped me shoot all wires and determined pcm was bad. friend I was helping could not afford one so waited a year until I bought one and put it in. spark returned but by this time fuel pump quit. again the pump was not replaced until it sat two years. just replaced pump and vehicle started and ran at idle for 35 minutes and shut off. Now it has no spark and fuel relay does not click on when ignition is turned on. Not even for the one second. No clicks at the fuel pump relay. Is there something external to the PCM that will disable both fuel and spark? I can get fuel pressure by jumping the contacts at the fuel pump relay.
Submitted: 1 year ago.
Category: Car
Expert:  Amedee replied 1 year ago.

AMEDEE :

Hello and welcome to Just Answer! My name is XXXXX XXXXX I can assist you with your question.

AMEDEE :

Please allow me to ask a few questions in order to better help resolve your concern

AMEDEE :

You are saying there is no fuel and spark when cranking it over now correct?

AMEDEE :

Are there any codes in the computer?

Customer:

Don't know I have no way of downloading at home. what is the sequence for ignition switching to invoke them. Can't remember. Also no hard check engine light

AMEDEE :

Turning the key on and off three times and then back on all within three seconds should get the cluster to flash the stored codes in the PCM

AMEDEE :

What about fuel and spark?

AMEDEE :

Are both missing when cranking the engine over?

AMEDEE :

Hello?

Customer:

I will go check. we have been disconnecting the battery in between xshooting so I don't know if they were cleared be right back! left battery connected. attempted start three times 20 sec each. tried on off 3 times but only saw left hand dash trouble lights come on once and turn off . no cyling of a code?

AMEDEE :

Sorry for the delay!

AMEDEE :

If there are no codes stored in the computer, then we diagnose no spark and fuel the old fashion way

AMEDEE :

If there is no fuel pressure, we check power to the fuel pump while cranking

AMEDEE :

if there is no spark, we check for power going into the ignition coil while cranking it over

AMEDEE :

I see you are now off line

Expert:  Amedee replied 1 year ago.

Since you have went off line before we finished our conversation, I am going to recommend a few more things for you to check.

 

First is going to be both the camshaft and crankshaft position sensors. Both of these can go bad preventing the engine from getting spark and fuel.

 

Also, be sure that the timing chain did not break, stretch or jump time as this will also cause a no spark and fuel condition.

 

If your not getting any fuel pressure when cranking, check for power to the fuel pump.

 

IF there is no ASD relay operation when cranking and no fuel pressure when cranking, check to be sure that the computer is awake with the key on. You can check this by checking for 5 volts going to the TPS with the key on.

 

Let me know what you find!

 

Amedee

Customer: replied 1 year ago.


Sorry I disappeared small emergency. I checked the harness to the coil under cranking and there was no voltage. Ohming harness shows one open and the other a direct short. The TPS with ignition on shows 2 VDC on pin 1 and 2. When the fuel pum was changed the engine cranked up normally and ran at idle for approx. 30 mins. then it shut off. it rekranked an ran for about a minute. the lat time before final death it cranked and the rpms jumped to 2 grand then tried to die and sounded like some misfiring was going on just prior to dieing.

Expert:  Amedee replied 1 year ago.
Hello!

If there is no voltage to the ignition coil while cranking, the ASD circuit is not working. This means you will need to check to see if the computer is grounding the ASD relay when cranking the engine over. If not, then we need to check all inputs to the computer. This is all powers and grounds. Also, be sure that the cam and crank sensors are not shorting out the computer.
Customer: replied 1 year ago.


Kind of what I was thinking. I will go out and disconnect each sensor that ties into K4 splice power one at a time and see if the voltage comes up at the TPS. Where is this K4 splice located. Be back in a while after I check

Expert:  Amedee replied 1 year ago.
I don't know off of the top of my head. Which circuit goes through the K4 connector?
Customer: replied 1 year ago.

the K4 is where all the sensors pick up there 5 volt excitation up to 96. kind of a bad designe since any sensor can take out the system. they changed in in 97 supposedly. Any way I went out and disconnected all applicable sensors and the cam sensor was the one drawing it down to 2 volts so hopefully this is it. I'm going to order one and will let you know when it comes in. Thanx loads for now and will recontact you when it is replaced.

Expert:  Amedee replied 1 year ago.
Sounds good! I think we hit it right on the head!

Please let me know how it goes!

Amedee
Customer: replied 1 year ago.


Tried to order the sensor from the big three and all their listings were the wrong part. Called one (Advance) about there internet problem and got the response it was a dealer only item. Thought it was funny since I replaced one in the wifes jeep recently and it was from them. Found a pile of them on e-bay but I will have to wait until thurs to get back to you when it comes in. Enjoy the race

Expert:  Amedee replied 1 year ago.
Sounds good! Will do! Thanks for the heads up.

Amedee
Expert:  Amedee replied 1 year ago.
Hello!

Its Amedee from just answer. I am just checking in to see how things are going and to see if you need any further assistance. Please let me know.

Amedee
Customer: replied 1 year ago.

The part is not due here until thurs. I will let you know how it goes then

Expert:  Amedee replied 1 year ago.
Sounds good!

Thanks for the heads up!

Amedee
Customer: replied 1 year ago.

OK now I am really lost. The 5 volts I checked for at the TPS was only 2 volts when you had me check it. I disconnected all the sensors one at a time that received the 5 volts and when I disconnected the cam position sensor I got the 5 back and could hear the fuel pump and ASD relays energizing. I reconnected everything except the CPS and still had the 5 volts. I ordered the sensor and replaced it just now and I am back to 2 volts with it disconnected. I am measuring the for the voltage at the TPS. I have since redisconnected the MAP, TPS, crankshaft sensor, cam sensor, Oil sensor, water temp, both AC hi-lo, brakes, coil, pretty much everything except injectors and I still have the voltage drain only showing 2 volts at the TPS. ????????

Expert:  Amedee replied 1 year ago.
Hello!

If the cam sensor is shorting the reference voltage down with the key on, the cam sensor is bad and will need to be replaced. If the crank sensor is shorted out, it too will need to be replaced. If none of the sensors are shorting this circuit out and the wiring checks out ok from the PCM to these sensors, the PCM is bad and will need to be replaced.

Amedee
Customer: replied 1 year ago.

I know that all makes sense. Here is the problem. Facts: The reference voltage on the J6 bus has been measured at 3 and not 5 volts when things don't work. The old cam sensor was disconnected and this voltage returned to its 5 VDC. I replaced the cam sensor and the J6 voltage read at the TPS dropped back to the 2 VDC initially encountered. I initially thought it was the J4 splice circuit but have discovered that was the ground circuit. The J6 is the 5 VDC excitation to all sensors. What I don't understand is I measure the same potential off the TPS on both the J6 pin 3 (5VDC) circuit of the TPS and center tap pin 2 (2VDC instead of 5 VDC). This initially made me believe they were shorted somehow. But ohm check proved this wrong. Not knowing where This seriously depressed me since I thought I had found the problem with your guidance. I took a break and went back out and thought of the other two sensors on the J^ bus not disconnected. I then went and disconnected the O2 sensor and tranny speed sensor in succession. When the tranny speed sensor was disconnected the Voltage reading on the TPS returned to 5 and the fuel and ASD relays began operating. The tranny speed sensor was reconnected and the voltage remained at 5 VDC. This is similar to my disconnecting the cam sensor with the same results. Since the relays were now kicking the vehicle started right up but I am afraid the problem is not truly fixed. Do you have the schematics for this ignition system to PCM connections. The vehicle was left running for 1/2 hour and all harnesses were massaged to see if they would cause a shut down. So far I can't duplicate the problem again and feel xshooting would be worthless until it re manifests itself. Sorry this is getting so involved. HELP!!!!!

Expert:  Amedee replied 1 year ago.
Hello!

Thanks for the detail.

The problem is that this issue is intermittent. This is what is making it hard to diagnose. I am just trying to help.

I have wiring diagrams. I need you to be specific. Which wire diagram or circuit would you like?
Customer: replied 1 year ago.

Essentially the voltage inputs to the PSM (power in and voltage level) and how they distribute to the power distribution splices J6,J7 and J4 (I think ground splice) to the multiple sensors they feed. and any ideas how the TPS 8 volt input and 5 volt input could both be at 2 VDC. I think the schematics will help me narrow this down, The PSM is new as well as the fuel pump and now the Cam sensor.?????

Expert:  Amedee replied 1 year ago.
Hello!

This only happens because of a bad PCM, wiring issue or a shorted out sensor.

Let me know which circuit you would like a diagram of..
Customer: replied 1 year ago.


The one showing PCM voltage inputs and outputs to the sensors in question on the J6, J7 and J4 circuits. The location of these splice points would also be helpful.

Expert:  Amedee replied 1 year ago.
Can you tell me the circuits these splices are on?

Customer: replied 1 year ago.


I'm not familiar with specific literature jargon. I need to see the PCM 12 volt input lines and more specifically the 5VDC output from the PCM to the sensors which all ties into the J6 splice. There is also an 8VDC output from the PCM that ties some of them into a J7 splice. The Hayes manual ignition diagrams only how they are electrically connected not locations of splices or any other specifics

Expert:  Amedee replied 1 year ago.
Hello!

Are you looking for a wiring diagram or the PCM connector view?
Customer: replied 1 year ago.

both

Expert:  Amedee replied 1 year ago.
NO problem!

Which circuit would you like a wiring diagram for?

Customer: replied 1 year ago.


I can't define it any clearer than I have in the previous strings. The hayes manual identifies it as the fuel injection wiring diagram. Maybe if you list what you think I am looking for I can pick the necessary ones. An exploded view of the inside of the PCM would be very helpful since I am reading the same voltage potential off pin 1 and 2 when it is bad at 2VDC and good at 5 VDC these feed pins 6 and 22 at the PCM

Customer: replied 1 year ago.


I don't understand this system. Am I supposed to be rating each reply or wait until the question is resolved?

Expert:  Amedee replied 1 year ago.
Hello and sorry for the delay!

You are supposed to rate my answer when you are satisfied with my assistance. We can continue this conversation as long as needed.

They don't make a wiring diagram for the inside of the PCM. However, here are two wiring diagrams that cover all fuel injectors on this vehicle.

graphic
graphic
Customer: replied 1 year ago.

The vehicle has started normally once a day for three days. Yesterday it would not start and is back to the 2 VDC on the TPC instead of 5 VDC. This power comes from the PCM and feeds most sensors. It all connects at a splice area labeled J6. Do any manuals describe where this splice area is located or do I have to rip up the harness and follow the wire until I discover it. I think I have a high resistance to ground and that is why it is intermittent. The plan is to isolate each wire at the splice until the culprit can be determined.

Customer: replied 1 year ago.
Relist: Incomplete answer.
I need to know where the J6 splice on a 96 D Dakota P/U is located. This splice receives 5VDC from the PCM and distributes it to almost all the sensors on the engine. please read all threads to see full nature of the problem
Expert:  Josie-Mod replied 1 year ago.
Hi, I'm a moderator for this topic. I've been working hard to find a professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you. Thank you!
Customer: replied 1 year ago.


yes

Expert:  Josie-Mod replied 1 year ago.
Hello

Thank you, XXXXX XXXXX continue to look for a professional to assist you. Please let me know if I can be of any further assistance while you wait.

Best,
Josie~Moderator
Expert:  Josie-Mod replied 1 year ago.
Hello again :)

We are still working with our professionals to find you the best possible match. But I wanted to touch base to see if you were still needing our professionals' assistance.

Please let me know if you would like to continue to wait or if you would like to cancel your question at this time. We sincerely XXXXX XXXXX the extended wait time.

Thank you,

Josie~Moderator
Customer: replied 1 year ago.

I am sitting here with a truck that runs intermittently. If you go back through the string I obviously have troubleshot this to its end. All I am asking is where is the J7, J4, J6. splice locations for said vehicle to prevent me from having to tear the whole harness apart. These splice identifiers are in the Hayes manual but location is not given. Is this the greatest MOPAR secret known to man. With all the wiring problems I see listed for this family of vehicles I am not understanding how this question is so elusive?

Expert:  K. Wiggins replied 1 year ago.

Hello, new expert here to assist you. I know what you're looking for, the splice location that feeds 5 volts to the sensors, got ya there. The program I use has them listed a little different than the Haynes manual but that's no problem. I'll post the complete diagrams below and you can cross reference the splice number with the chart I will post also then just look at the pictures for the splice location. Let me know if I can help you further.
Diagrams
Splice index and locations
^ those are for the two wheel drive models if yours is 4wd just let me know and I'll post those.

 

 

Looking at the diagrams it seems to be splice 123 that feeds the cam, crank and tps sensor

Customer: replied 1 year ago.

# XXXXX thank you for your response. Sorry I'm so slow to respond. I am a school teacher and we just started back up so things are a little hectic. The splice area chart is exactly what I needed. The diagram is for the ignition side and does not display splice 123. Do you have a diagram of the sensor wiring that shows the 5 VDC from the PCM to them. If you say it is definitively splice 123 near the starter solenoid that is where I will go. I am assuming one of the sensors or the harness has a high resistance short to ground. I am confused how disconnecting the sensors temporarily cures it and one time it was the cam sensor disconnect that returned the voltage and the next time it was the speed sensor on the rear of the tranny????

Expert:  K. Wiggins replied 1 year ago.
Hello, it's no problem we can work at your pace. I'm online daily and will respond ASAP.
Looking at diagrams from a few different sources to better assist you. It seems the speed sensor is spliced in with the map sensor. What I would suggest is finding which pin is the 5 volt reference at each sensor then using a ohm meter on that pin to check continuity to ground. It's possible the sensor is only grounding when hot.
also examine the harness itself. Go to each sensor with key on and find the 5 volt reference and mark it. Then with key of check resistance to ground with an ohm meter. Shake the harness to see if resistance changes to indicate a short.
I'm fairly certain it's either a sensor shorting to ground when hot or a chaffed wire in the harness hats causing the 5 volt reference to short.
Let me know what you find and I will do my best to assist you further. I'll post all the diagrams I have below for your reference.
graphic Click here for system diagram (simplified and easy to read. I suggest printing and taping the pages together.)
Customer: replied 1 year ago.

Thanx, these are exactly what I have been asking for. I have checked for shorts to ground with no luck but that was with a standard voltmeter. I don't have anything to check for high resistance shorts. Its raining here all weekend so I won't get a chance until it stops. I'll let you know what I find

Expert:  K. Wiggins replied 1 year ago.
Sounds good
Customer: replied 1 year ago.

Eureka, the harness side of the plug from the cam sensor, where it joins the main harness (I believe it is the splice 123 you mentioned) when moved was dropping the 5VDC down to 2VDC. After enough movement I could even get a dead short to ground finally. Question? are there any ground wires in the harness at that splice area, it does not appear to be a harness chaffing to metal type problem (superficially). I massage what feels like the splice area and it makes and breaks the ground. Have you ever had to repair this area? It looks like either the tranny or engine has to come out to gain access. I used to work on F-4's but this is in a place that rivals even their peculiarities.

Customer: replied 1 year ago.

Dude! I don't know what just happened but my pc just told me it opened to other experts. Not my intent at all. You have got me to the solution and I need to stay put. please advise

Expert:  K. Wiggins replied 1 year ago.
Great, glad you found it. There is a ground for that sensor that may be bundled in that harness it's a black and light blue wire. It's been quite some time since I've worked on the wiring in one of those trucks. You may be able to disconnect the harness and "pull it up" so to speak to be able to gain better access to the wires. If that's a no go I'd try pulling the tranny first since it's a little less involved to remove. I know that's not much in the way of good news but at least you have isolated the problem so the battle is half over.
K. Wiggins, ASE Certified Technician
Category: Car
Satisfied Customers: 1485
Experience: Associates Degree
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