I’d run a quick bypass test of the crank sensor unplugged. I don’t have time to type it out, but YouTube “crank position bypass test”. Listen for relays clicking and the fuel pump turning on when you do it. You’re just essentially pretending to be the sensor to verify wiring. Way easier and quicker than ohms/continuity checks. Also make sure your ground is good. Load it with either a test light or your probe.
P0320 dead on road
- Thread starter 4BY4ADV
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Also, that video is kind of blurry. It’s for sure going from 5 volts to Zero? What’s the max reading?
Make sure the sensor is seated all the way down and that there isn’t any corrosion under the sensor. Gap issues on new sensors can also cause problems.
I apologize for the sporadic messages. I’m busy but trying to help.
Make sure the sensor is seated all the way down and that there isn’t any corrosion under the sensor. Gap issues on new sensors can also cause problems.
I apologize for the sporadic messages. I’m busy but trying to help.
I just learned this the hard way. I had the same codes as the OP and bought cheap sensors to see if it would fix the problem. They worked great.......for about 4 hours total driving time, before leaving me stranding once again. I ordered NTK cam and crank sensors, installed them, and all has been good for over 10-12 hours total driving time.
Crank position sensor.
Testing from harness side behind the connector.
Video should be clearer if you click the gear icon and change resolution to 1080p for playback. Yes, 5v(5.3ish) and 0.
Fully seated and no corrosion at connector or at PCM.
I’ll check the cam sensor wiring and test that wave form tonight. Considering I was in a hurry that day and didn’t change my oil myself, it’s possible the tech changing the oil filter messed with the wires going to the cam sensor as they are right there.
Also, found a NOS Mopar crank position sensor on eBay and bought it. Plan on swapping that when it arrives.
Testing from harness side behind the connector.
Video should be clearer if you click the gear icon and change resolution to 1080p for playback. Yes, 5v(5.3ish) and 0.
Fully seated and no corrosion at connector or at PCM.
I’ll check the cam sensor wiring and test that wave form tonight. Considering I was in a hurry that day and didn’t change my oil myself, it’s possible the tech changing the oil filter messed with the wires going to the cam sensor as they are right there.
Also, found a NOS Mopar crank position sensor on eBay and bought it. Plan on swapping that when it arrives.
Nope. I don’t care what the connector looks like visually. You either need to take the back cover off the PCM connector, backprobe, and test for the same signal AT the PCM, or at minimum run a bypass test to make sure the PCM can receive and respond to a crank signal.
You’ve gone further than most with the troubleshooting. Don’t quit now.
Crankshaft PS wave form from back of PCM looks identical.
What should the Camshaft PS waveform look like? I left the oscilloscope on the same settings and it looked very different. More like off for a period, on for a period. Not the tightly spaced square waves. Tested at 50ms, 10ms, and 5ms.
What should the Camshaft PS waveform look like? I left the oscilloscope on the same settings and it looked very different. More like off for a period, on for a period. Not the tightly spaced square waves. Tested at 50ms, 10ms, and 5ms.
hmmmmm.... doesn't sound right. Google a "known good tj camshaft waveform" for your year. Should look very similar to the crank wave form. Keep in mind the camshaft spins at a slower rpm as the crank.
Edit: Might be good. You just need to dig a little to verify. Make sure you're also testing the cam signal at the PCM as well.
Yes, I’m testing at the PCM. Camshaft waveform looks similar.
So I’m guessing I’m now looking at a timing issue? Is there another diagnostic I can run? I’m guessing I’d need to match the waveforms which would require equipment I don’t have.
Or at this point is it just a “swap the distributor and cross your fingers” juncture?
So I’m guessing I’m now looking at a timing issue? Is there another diagnostic I can run? I’m guessing I’d need to match the waveforms which would require equipment I don’t have.
Or at this point is it just a “swap the distributor and cross your fingers” juncture?
Well, my man... I hate to be this guy. But.... I'd attempt changing both sensors to either Mopar or NTK (or whatever other reputable brand you research.) before I changed the distributor.
Here's the facts. Chrysler is insanely picky about their cam, crank, and O2 heater circuits. This is no shit, it's just true. I have seen, heard, and experienced this very thing. Unfortunately, you have to jump through the hoops that you've jumped through to verify it's not something else. But here you are.
There are three possible problems that exist at this point.
- Either your pin drag on the cam or crank signal wire at the PCM is bad (yeah right, but should be looked at to eliminate it.)
- The PCM is cooked (highly doubt it)
- Or, one of the crappy sensors is sending a crappy signal the PCM doesn't like.
And don't feel bad if it ends up being the crappy signal. A Pico Scope and a trained eye sometimes have a hard time discerning what exactly a Chrysler PCM isn't happy with. The fact that you're unable to pinpoint what's wrong with the signal on a power probe is nothing to be ashamed of. I commend you for actually testing up to this point.
Replaced both sensors with mopar. Still same result.
Put a spark plug light inline with cylinder one and got a weak/dim flash. Charging the battery up as it’s not happy from all the failed starts.
Will try again after charging to see if the light is still dim.
Getting a mopar coil will take some time. Are we in the same boat with auto part stores ignition coils? Or can I just pick one up from Autozone?
Put a spark plug light inline with cylinder one and got a weak/dim flash. Charging the battery up as it’s not happy from all the failed starts.
Will try again after charging to see if the light is still dim.
Getting a mopar coil will take some time. Are we in the same boat with auto part stores ignition coils? Or can I just pick one up from Autozone?
Charged battery and moved the light to the coil wire and I see a consistent flash.
Wtf else should I be looking for here? Fuel pump is only a few months old and I can’t imagine that just went.
Should I just pull the distributor and replace it again?(I’d guess about 10 months old).
Really frustrating considering I replaced the engine just over a year ago.
Wtf else should I be looking for here? Fuel pump is only a few months old and I can’t imagine that just went.
Should I just pull the distributor and replace it again?(I’d guess about 10 months old).
Really frustrating considering I replaced the engine just over a year ago.
So after you clear codes, the P0320 comes right back?
Are there drivability issues even when the check engine light is out?
Do you have access to a scan tool with live data?
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No codes at the moment.
It won’t start, so I can’t speak to drivability issues.
I’ve got a Scangauge ii and a FIXD Bluetooth code reader. They give some live data but it’s not even starting/running.
I’ve got an autozone and a harbor freight 2 blocks away, so at least I have quick access to tools/parts that aren’t already in my garage.
It won’t start, so I can’t speak to drivability issues.
I’ve got a Scangauge ii and a FIXD Bluetooth code reader. They give some live data but it’s not even starting/running.
I’ve got an autozone and a harbor freight 2 blocks away, so at least I have quick access to tools/parts that aren’t already in my garage.
Pull up the RPM data PID and crank it. If RPM doesn’t register, you’re still in the same boat with everything I listed above. It would mean the PCM isn’t receiving signal or can’t see the signal. A coil isn’t the cause if that’s the case.
If it doesn’t register, I’d be a tapping and wiggling fool while someone cranked it. This could be an intermittent connection issue or slight break or short in the signal wire, or a loose terminal at the Crank connector or pcm. Wiggle the harness, tap on the connectors all while someone’s cranking and looking for the rpm to pick up.
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Whether it makes sense to or not, I’m testing other things too.
ASD circuit appears fine. Removed relay and probed the connections. 12v constant, 12v when ignition turned on, ground…
Pulled O2 fuse, power to ASD circuit gives power to O2 circuit.
Swapped ASD and horn relays.
I keep going back to the no start with occasional pop. It sounds like when I installed my distributor and the helical gear was off by one tooth. I punched the roll pin out, flipped the gear, reinstalled, and then the jeep ran great.
So, is it possibly a timing issue I’m struggling to diagnose here?
ASD circuit appears fine. Removed relay and probed the connections. 12v constant, 12v when ignition turned on, ground…
Pulled O2 fuse, power to ASD circuit gives power to O2 circuit.
Swapped ASD and horn relays.
I keep going back to the no start with occasional pop. It sounds like when I installed my distributor and the helical gear was off by one tooth. I punched the roll pin out, flipped the gear, reinstalled, and then the jeep ran great.
So, is it possibly a timing issue I’m struggling to diagnose here?
Possibly. Good work so far!
Got a timing light? Could verify what the PCM is saying timing is vs actual.
-Mac
Got a timing light? Could verify what the PCM is saying timing is vs actual.
-Mac
I haven’t seen my timing light in… more than a decade and several moves. hahaha.
I can however go and pick one up at lunch. Forgive me here… but what exactly am I looking for that would help me match the PCM to actual? I mean I can get someone to turn the key while I look at the timing marks. Am I matching that up to a timing/advance PID?
I can however go and pick one up at lunch. Forgive me here… but what exactly am I looking for that would help me match the PCM to actual? I mean I can get someone to turn the key while I look at the timing marks. Am I matching that up to a timing/advance PID?
Theoretically here...never done it...I believe there are timing marks on the timing chain cover.
And I believe there is a timing PID.
I'm guessing here but before I started messing with my distributor I'd try and see if those two values lined up.
That might be more trouble than it's worth.
Might also want to get a good look at your timing chain and sprockets and make sure you didn't jump a tooth.
-Mac
P.S. Now where did I stash my timing light. It's been a long while...
And I believe there is a timing PID.
I'm guessing here but before I started messing with my distributor I'd try and see if those two values lined up.
That might be more trouble than it's worth.
Might also want to get a good look at your timing chain and sprockets and make sure you didn't jump a tooth.
-Mac
P.S. Now where did I stash my timing light. It's been a long while...