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powertrain control module

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7mopar

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Anyone know of a source for information of the internal working of powertrain control modules that does not require a electrical engineering degree to understand. My 93 Dakota is being a pain in the butt. Have been losing the ignition circuit with engine compartment hot. So far will restart after cooling down. I have the engine harness and powertrain control module wiring diagrams and carry an electrical multi tester. Hope to start illuminating power circuits and find the problem before it strands us. All that my Snap-on diagnostic will tell me is it is ready to drive and shows no error codes. All that I know at this time is there is no current to the coil (term #19) or check engine light when this occurs and will not restart till the check engine light comes on. There is current at Terminals #7,9 & 20 and voltage levels test ok.
 
I'm not sure on the control module . But I had a 90 full size truck in here a while back that would run fine when it was cold and when it got warmed up it would die . Not all the time but most of the time .It had no spark and sometimes no juice to the coil and no codes showing . It ended up being the hail effect sensor , I think that's what they call it , I call it a magnetic pick up that in the distributor .
 
The wiring diagram calls it a camshaft position sensor and them locates it half way across the drawing from the distributor. Will stop at NAPA and see if they can find a distributor pick-up got to get it dependable again.
 
Replaced the distributor plate ( aka cam sensor - hall effect ). Definitely runs better but did not fix the original loss of electrical to coil when hot.
My local source of info suggest replacing the ignition switch any thoughts on this out there? Would be the logical thing but all fused circuits power up on ign #1
 
I've had the ignition switch cause no juice to the ignition on a couple of these trucks but every time I've come across this problem the switch it's self felt funny . I'm not sure how to explain it , It was almost like the key was turning but not inside . If that makes sense ? There's definitely no codes coming up ?
 
No codes at all. In fact the check engine light will not even light when trying to start it. I have been letting it sit with the hood open some times 10 - 30 minutes check engine light works again and starts right up.
 
The cam position sensor was the first thing I would have suspected based upon the symptoms. Bear in mind that corrosion on wire connections causes them to heat up and increased results in more resistance. A the heat-resistance snowballs until no current can pass until things cool down. You might make a jumper wire and the next time it does it, run the jumper from the positive battery terminal to the hot side of the coil and see if it starts and runs. If so, at least you've narrowed things down because you know the CPS, ignition module and all wiring past the coil is ok.
 
If you have a tilt steering column, check the wiring right at the ignition switch, the wiring may have partially pulled from the connector losing contact with heat
 
Will check it out but I am not convinced it is where the problem is as I have checked all circuits from the switch and have battery voltage when the system shuts down that and the fact if the hood is opened after intensional shut downs I do not get heat saturation to what ever part is shutting the system down. Have ordered a new crank sensor. From what info I could find it is the only sensor that sends a signal to the ECU in open loop to activate the coil and injectors. After 142000 miles will more than likely not hurts to change in anyway. Will let everyone know the outcome and it will be a delight to have this problem go away.
 
Time for an update. New crank sensor has been installed and ignition switch wiring has been checked. Length of time before shutdown has been greatly increased and recovery time after heat saturation has decreased. But problem has not been solved as yet. A review of what has been done - new parts - O2 sensor, hall effect switch/cam sensor, crank sensor and ignition coil. The complete secondary ignitions system has been replaced. Shows no codes while running. My Snap-on scan tool tells me all systems are ok. All sensor and computer connections have been checked. Battery connections, ignition switch power circuit to fuse box, engine harness and power panel circuits have been checked. Auto shutdown relay has been checked and all battery feed circuits to the ecm. Fuel pressure has also been checked before starting and while running, have a constant 32 psi. well within range. Let it get hot and shuts down no ignition and no fuel. If this where only obd II instead of obd I. I have also tried an ice pack on the ecm once with no positive affect. Any ideas as to what to look at next? Presently stumped but have not given up.
 
The old FI cars had a re-settable pendulem switch that would deactivate the fuel pump and-or ignition system after a sharp impact. FI motorcycles have the same switch, which many people call a "tip over" switch. It does the same thing, it shuts things down after you dump the bike. They have been known to go bad and intermittently shut things down when you least expect it. I'm sure the newer vehicles have the same type of switch, although I have no idea of where or what it is. Might be something to look into. Over the years I've found that sometimes the solution to a problem isn't the most obvious or expected one; sometimes it's the most unexpected.
 
Replaced the ignition switch last night. Problem still exist. I do notice something different today after it shut down. I had the ignition on auxiliary and the door open and no door buzzer working , just sitting there listening to the radio trying to stay cool and catch up on email. Suddenly the door buzzer starts and I turn to ignition switch to run check engine light was on and the thing starts. What would the two systems have in common that I all ready have or have not checked? Also what triggers the ASD relay? All I can find on it is what it shuts down (ignition and fuel pump). Could it be possible I disturbed something while replacing the fuel lines? I replaced both the pressure and return line from the plastic line off the tank to the plastic lines to the fuel pressure regulator all new metal lines. As stated before pressure to the fuel rail has been checked while running and after it shuts down and no loose of fuel pressure. Just had a thought and I am going to check the evac diagram tomorrow it is available under the hood at least and see what I can find in the system? Thanks for all the reply.
 
Get one of these manuals....it will help $8.99 cheap enough

1993 Dodge 3.9L 5.2L 5.9L Fuel Injection SFI Powertain Diagnostic Dealer Manual
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It takes a Mopar DRB II tool...rare and expensive. Rumor has it that an Innova 3120 w/right adaptor will work, but I don't know this for a fact.
 
That would be an odd combination as it is obd 1 and have the Chrysler can on a Snap On Scanner.
 
Odd indeed....my '93 D150 is not OBD and it has the same ECU as the '93 Dak. I have a copy of the ECU application guide that says it's the same ECU but no Dak FSM to refer to. DRB II is the only way to access my truck.
 
Do you use a special adaptor for your OBD ll scanner? My Snap On scanner requires the use of 2 test cans 1 basic for years 84-93 and a additional for I believe 89-93.There is a can for 94 and in 95 I think everything went to OBD ll with the universal cable.
 
Still OBD just manufacture specific testing modules are required (on board diagnostic) not to be confused with OBD II which standardized all vechical operating systems manufactured in the US. I have one of the old scan tools for the type plug in the diagram you posted. It will display live data and show error codes that are available. Unfortunately the problem my vehicals is experiencing is not considered an error buy the computer.
 
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