How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dodgerench Your Own Question
Dodgerench
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3385
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
4486286
Type Your Dodge Question Here...
Dodgerench is online now
A new question is answered every 9 seconds

I got a 92 dodge Dakota with a 5.2L with a no start

Customer Question

i got a 92 dodge Dakota with a 5.2L with a no start condition. it turns over.
there is no spark. the coil is getting 12v source voltage from the one wire while cranking and is getting 6volts on the other wire when cranking. so I suspected the coil and replaced it.
I still have voltage to the coil just no spark after coil.
does the coil need to be getting 12v at both wires to fire? and should one of them be turning on and off? it seems to be a solid 6volts
Submitted: 1 year ago.
Category: Dodge
Expert:  Dodgerench replied 1 year ago.

Goood afternoon, this is Ed. Welcome to JustAnswer!.

Yes, the control side of the coil (grey/ black wire) should be flashing while you're cranking, but your meter might be averaging out the reading.

Regardless, you apparently have some sort of voltage drop over the new coil, something that can only happen if a load is applied on that same control-side circuit. If the PCM was doing its job properly and switching the circuit to produce the volt drop, you'd be getting spark. So I'm thinking your observation about the circuit being "smooth" and 6 volts is accurate.

I'm tempted to suggest that the PCM's internal coil driver is shorted out, but we should check the circuit out first, just in case it's shorted somehow between the coil and the PCM.

The first thing I'd be interested to know would be... whether an aftermarket tachometer or anything else has been tapped into the control circuit. If so, remove it and see if your spark returns.

Expert:  Dodgerench replied 1 year ago.

If nothing has been added, we need to check the coil control circuit for short to ground next.

Disconnect the coil primary connector and check resistance between the grey/black wire and battery negative (or any known good ground source). It should be an open circuit. Any continuity at all with the coil primary connector dangling shows it's finding ground somewhere.

Customer: replied 1 year ago.
there is no tach or anything aftermarket installed. there was a remote car starter but that was removed and the truck was running fine until the other day I will go check the control circuit
Expert:  Dodgerench replied 1 year ago.

Aaaaaaand that somewhere might be through the PCM. It's odd to see a specific amount of voltage drop in the circuit like that, that's caused by an accidental short to ground. It smells more like a switching transistor in the PCM that's gone bad.

So, if you find any sort of electrical continuity (well... I'd say 500 ohms or less) on your test, disconnect the PCM next to see if it goes away.

Expert:  Dodgerench replied 1 year ago.

Hi!

Expert:  Dodgerench replied 1 year ago.

Take a 5/16" (8mm) socket with you for PCM disconnect if needed.

Customer: replied 1 year ago.
ok I checked resistance in the grey wire with the truck off between coil plug and negative on battery. got 11.5 on the 200k setting on ohm meterunplugged the pcm and it went away
Expert:  Dodgerench replied 1 year ago.

Ooo. That's not good.

Expert:  Dodgerench replied 1 year ago.

There's no reason why the PCM should be sucking power constantly like that.

Customer: replied 1 year ago.
could there be another part or sensor interfering or does that mean its definetly a problem in the PCM?
Expert:  Dodgerench replied 1 year ago.

Since the circuit went open when you unplugged the PCM, the only possibility would be a wiring problem very VERY near the point where you unplugged the controller. Try reconnecting and disconnecting it a few times to eliminate any possibility of a harness problem. If the short returns each time you reconnect the PCM, it's curtains for your controller.

The good news (if any) is that you can use a junkyard controller with no problems. They don't need to be VIN-programmed or anything, just the right part number.

Customer: replied 1 year ago.
okay I will try that
Expert:  Dodgerench replied 1 year ago.

I'm not sure what your true ohm reading is now that I think about it. Take your meter down to the lowest scale that you can where the meter shows some sort of continuity. I'm not sure if you're reading 11.5K ohms or 11.5 ohms...

Customer: replied 1 year ago.
the ohm meter I have starts at 200, then 2000, then 20k, 200k, 2000kthe lowest spot I get a reading is at 20k= 10.63I get nothing lower then that
Customer: replied 1 year ago.
I looked at the wiring just before the plug going into the pcm and I cant see any issues. I plugged it in and unplugged it a couple times still with the same result.so because I am getting voltage to the coil that rules out other sensors like the cam position sensor in the distributor cap and the crank position sensor correct?also there is no fault codes or a check engine light on.is there a way for me to actually test the PCM to make sure that is the problem
Expert:  Dodgerench replied 1 year ago.

Thanks. That would be 10,630 ohms, which is pretty high. Let's try turning the key on and rechecking the circuit with the PcM plugged in. It's a near certainty that you'll need a PcM but I'd like to see the circuit drop lower for a positive diagnosis.

Expert:  Dodgerench replied 1 year ago.

You're right about the cam or crank sensor and distributor cap. If the PCM didn't like what it was seeing from cam or crank, it wouldn't bother to try igniting the coil and you'd wind up with equal voltages on both sides of the coil connector. And the distributor cap isn't even a factor since it doesn't have spark to distribute. =/

Customer: replied 1 year ago.
with the key turned to the on position (not cranking) I get 12.03ohms at 20k
Expert:  Dodgerench replied 1 year ago.

Aaaargh. That's still not what I was expecting.

Let's try something else. Locate the ASD relay in your underhood fuse and relay box. Pull the relay and look at the base of the unit.

It should be marked with numbers like 30, 85, 86 and 87. It might not be (the wiring diagrams were different in the early Dakota years, so the relay might not show these numbers).

What I'd like to do would be to jumper 12v to the ASD circuit (same one that feeds the coil) and see if voltage on the control side of the coil still drops with everything connected.

To jump 12v to the circuit, locate terminals 87 and 30. Jump 'em with a paper clip or something.

If the terminals aren't marked on the base of the relay, the two terminals you'd jump would be across from each other. One involves the odd-direction terminal and the one right on the other side of the pattern.

Then you'll need to backprobe the grey-black wire, turn the key on and see what your voltage is. With power supplied to the coil and the engine not cranking, the voltage should be equal on both sides.

Expert:  Dodgerench replied 1 year ago.

Be careful to avoid jumping terminals 85 and 86 together (the two same-direction terminals across from each other). That'll likely burn the PCM control driver for the ASD relay out.

Expert:  Dodgerench replied 1 year ago.

If the PCM sucks your control side voltage down without the engine even turning, nothing remains but to replace the PcM.

Customer: replied 1 year ago.
with everything plugged back in, the asd relay out jumping between the 30-87 I get close to battery voltage
Customer: replied 1 year ago.
while back probing the grey wire
Expert:  Dodgerench replied 1 year ago.

Interesting.

Customer: replied 1 year ago.
there was approx. half a volt difference beween what I got across the battery and what I got at the grey wire
Expert:  Dodgerench replied 1 year ago.

Do you have a 12-volt test light? Something that you could watch flash if connected to the grey wire?

If so, connect the test light's clamp it to battery positive and the other end to the grey wire. You won't have to plug the coil back in, just crank the engine. If the PCM causes the light to flash, it shows it's switching properly.

Expert:  Dodgerench replied 1 year ago.

You can un-jumper the ASD and put the relay back in. You'll be supplying your own power to the PCM coil driver through the test light.

Customer: replied 1 year ago.
I do have a test light but I have to step out and will have to get back to this a litte later today
Expert:  Dodgerench replied 1 year ago.

OK.

Customer: replied 1 year ago.
using a test light with the key on I have power between the grey wire and + terminal on the battery. when cranking there was nothing, the light was out
Expert:  Dodgerench replied 1 year ago.

The test light is lit with the key on only? (test light connected to B+ and to coil grey wire)

But no flashing at all when cranking and the test light just went out?

That doesn't fit what you were originally showing, somehow. I can't see how you could have a voltage drop when no current is being drawn by the PCM.

Let's start at the beginning. What happened to your truck orignally?

Did it die while driving?

Is this the first time it's happened?

How do you know there are no codes?

And how are you testing for spark?

Yeah, questions.. questions ..

Customer: replied 1 year ago.
yeah I thought it was weird. as soon as it started cranking there was no light at the grey wireI didn't use a a test light originally I used a multimeter from the wire to battery ground and had 6volts at that wire while cranking and nothing when not cranking.there is no check engine light on. so I switch the key on and off twice to manually retrieve codes. it flashes 5 times twice with no codes to follow
originally the truck wouldn't start so it got towed to my house, I could smell gas out of the exhaust when cranking and could hear the fuel pump cyling on when you turn the key so I checked for spark,pulled a spark plug wire, put my spark plug test on it and grounded it to negative on the battery, turned it over, had no spark, so I did the same with the wire going from the coil to distributor cap no spark.help the spark plug tester to the output of the coil, grounded to the battery and turned over, with no spark,pulled the plug going to the coil checked both wires with multimeter while cranking, had battery voltage at the green one and 6 at the grey one.I figured it was a bad coil so I replaced the coil. which leads me to contacting you because im kinda lost.
Customer: replied 1 year ago.
I think I know what I did wrong. I was checking the signal wire with multi meter from wire to the ground on the battery giving me 6volts for whatever reason when cranking..but I should have been checking from wire to positive on the battery..
Expert:  Dodgerench replied 1 year ago.

And my mistake was that I thought you had the coil connector plugged in while checking for voltage on the signal wire.

Did I read that right? You checked the coil's grey wire with it disconnected?

You're right about flash code 55... that shows end of test. If nothing came before it, that means you had no codes.

Next questions... Were you able to get a continuous 12 volts on the green/ black wire while cranking? The ASD relay won't stay energized unless it sees both cam and crank signals if memory serves.

Were you driving when the engine quit? Or was it simply a no-start one day?

Customer: replied 1 year ago.
it was a simple no start one day..I just hooked up the test light to the positive side of the battery and cranked it with no light on test light. so the coil is not getting a single.I unplugged the CPS sensor and turned the key on check all 3 connectors for power and got nothing. they way I read it is I should have 5 volts to one of them with the key on
Customer: replied 1 year ago.
I was actually checking the wrong side of the plug, I unplugged the sensor and was checking the sensor side for power
Expert:  Dodgerench replied 1 year ago.

Easy to do.

In this year for the crank sensor, you'll get 5v on the signal wire (another grey/ black one), 8v on the power wire (orange) and the black/ light blue wire is sensor ground (0v) with everything unplugged. The cam sensor (the one in the distributor) uses the same orange power and black/ light blue sensor ground wires, but its signal wire (also 5v) is tan/ yellow.

Plugged in, you will need to look for a toggle in the 5v signal as the engine is slowly rotated or bumped. If you crank it, your meter will just average the 0v-5v ranges into something in the middle. I'd like to know if you get good, sharp switching on these two sensors.

The cam sensor changes but once per engine rotation (360 deg), but the crank sensor will switch 5v-0v often as it encounters the signal windows in your flexplate. It's harder to get a good switchpoint on the crank sensor for that reason, but it should happen eventually.

Expert:  Dodgerench replied 1 year ago.

A 1v-4v switch isn't going to be recognized by the PCM, as the matrix isn't wide enough. It needs to be pretty close to that 5v-0v-5v range.

Expert:  Dodgerench replied 1 year ago.

The crank sensor is kinda hard to see, but the connector comes up and out near where the cam sensor connector is, over near the driver's side rear valve cover area.

Customer: replied 1 year ago.
I unplugged the Crank position sensor, I have 5v to one terminal and 8 to the other.
I cant turn it over anymore today as my helper had to leave.I just talked to the previous owner of the truck. he had an intermittent no start issue, he replaced the crank position sensor a few months back but it didn't fix the problem. he said it would just turn over and turn over and finally after a while it would fire. but it only happened once every few weeks.so now I know I don't have a signal going to the coil are they only things It can be a cam position sensor, crank position sensor, pcm or bad wiring? or is there anything else it could be?
Expert:  Dodgerench replied 1 year ago.

There could be an issue with cam-crank sync. The 92 3.9 and 5.2 Magnums had issues with the distributor drive gear and block bushing wearing out, which caused a "slide" on the cam sensor signal timing. As the gear wore out, the distributor became increasingly slower in providing its signal until sync was lost and the engine wouldn't start.

To check for a worn out drive gear, take the distributor cap off and see how much slop there is in the distributor rotor tip as you rotate it forward and back. If the swept area of the rotor tip exceeds about 5mm (somewhere around 1/4" or so), it suggests you have problems way down below. Just turning the distributor shaft counter-clockwise a small amount should get you back in-sync close enough to get the engine running again, until you can go deeper into the engine for that block bushing. I did a ton of these back in the day, but most were on the 3.9 engine for some reason. It was the same part, same everything , but the 3.9 suffered from worn out block bushing-itis much more often.

If you decide to bump the distributor a bit, be careful to avoid going too far (about 5 degrees should be plenty). There's a sync procedure I can describe for you, but it wouldn't make sense to go through all the trouble if the block bushing is worn out.

Customer: replied 1 year ago.
ok thanks. I have to call it quits for the day and im back to work tomorrow so I wont be able to look into it any further ontil tomorrow night. thanks for all your help this far
Expert:  Dodgerench replied 1 year ago.

No problemo. See you tomorrow!

Related Dodge Questions