Got a little technical question. My 2002 tj 4.0 5 spd with 221000+ miles would occasionally stutter some but otherwise ran great. The check engine light was on and I got P1391. I swapped the cam sensor, no change. Swapped the crank sensor, let it idle 10 minutes and drove it across the yard. Went to start it a few hours later and it cranks but won’t start. Getting the code “no crank signal”. Put the old sensor back on and still have “no crank signal”. Was my pcm going out and the new sensor sent it over the edge?
Is my PCM bad?
- Thread starter Jeff29520
- Start date
I’m going to check some wiring today. Then I’ll see what he suggests. I think the general consensus is wiring / plugs before pcm.
I have had wiring harness issues myself. Not sure what your are planning to check with the wiring, but in addition to everything else, leave the Jeep running and grab the main harness at as many points as you can get to and shake/bend/twist it all around. If the engine studders while you're doing the harness hokey pokey, you've found your issue, and that's what it's all about.
Good idea. Wish I would’ve done that before now. Gotta do it the hard way now.
Especially check the wiring harness at the rear of the engine just behind the valve cover where it bends around a threaded vertical stud. The threads are known to wear through the wiring as below. Adding a protective plastic or vinyl cover to that stud is never a bad idea.
I see exactly where you’re talking about. Rubbing but not all the way through yet.
Good morning gentlemen,
@Jeff29520 I do not think you have a pcm issue from what I have read about the p1391 code. It leads back to the following possibilities:
- Faulty Crankshaft Position Sensor (CKP)
- Crankshaft Position Sensor (CKP) harness is open or shorted
- Crankshaft Position Sensor (CKP) circuit poor electrical connection
- Timing belt or chain stretched or jumped
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.
- With the wiggle wire testings, shake them harder than someone who drinks Sanka but softer than Lou Ferrigno and chances are you’ll find something amuck. I would also check all powers, grounds and anything hooked up aftermarket as sometimes the difference between working and not working is a wire on a Jeep.
Appears to be the crank sensor plug. Squeezed it together and it fired up. I have pinned plugs before, but where can I get what I need for this one?
Another satisfied customer of the Wrangler TJ Forum and what the hell is wrong with my ride.
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Good morning gentlemen,
@Jeff29520 I do not think you have a pcm issue from what I have read about the p1391 code. It leads back to the following possibilities:
Please keep us updated on what you find out and definitely do not speed through Sumpter County, sir! Those boys would ticket their own families to make quota!
- Faulty Crankshaft Position Sensor (CKP)
- Crankshaft Position Sensor (CKP) harness is open or shorted
- Crankshaft Position Sensor (CKP) circuit poor electrical connection
- Timing belt or chain stretched or jumped
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.
- With the wiggle wire testings, shake them harder than someone who drinks Sanka but softer than Lou Ferrigno and chances are you’ll find something amuck. I would also check all powers, grounds and anything hooked up aftermarket as sometimes the difference between working and not working is a wire on a Jeep.
If I ever need a PCM I'm totally going with you
I would try to take it apart spray it with some contact cleaner. Get all the dirt and grime out the put some dielectric grease on it.
If that doesn't work. Most of the parts houses should be able to get you a pigtail.
Don't expect dielectric grease to improve connections. It's technically an insulator and can protect connections but it can't improve them. It can at times even make connections worse.
And you are correct it won't improve a connection. I always use it just to keep other junk from getting in there later.
Thanks. Hopefully I won’t need it. Sometimes I forget you can find anything on the internet. I was thinking old school extracting and replacing the pins.
Does anyone conclusively know the MOPAR part number for the Crankshaft Position Sensor on a 2000 TJ Wrangler Sahara with the 4.0 engine and a manual transmission?
Thank you in advance.
Thank you in advance.
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