Troubleshooting Some Error Codes

IkariBattousai

IkariBattousai

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Joined
Sep 27, 2019
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30
Location
Des Moines, IA
Hello all, I’m cirious what you all think. I lost power on the highway yesterday and pulled over and the engine died completely. Manual transmission with the clutch pedal to the floor so I know it’s not that. No CEL but a lamp test shows that my CEL is burned out which is great. Throw a code reader on it and I’m getting P0138, three codes for ignition coils, and the CK/CP sensor. Before I rush out and buy a bunch of sensors, does this seem more likely to be a wiring issue? I’ve had electrical gremlins before and I’m wondering if it’s less likely that all these sensors are out. Jeep is a 2000 4.0L with Federal Emissions and a 5 spd
 
Okay, so it turned out it wasn't that the bulb was burned out, but that the twist socket was bad so I pulled the one from the shift up light and popped it on the CEL and it came right on. Went ahead and cleared the codes and drove it around a bit the same night. No problems. Had a trip for the long weekend so today was the first time I was able to get back to it. Drove it around a bunch more and no problems. Tested the fuel pressure at the rail and it came back about 45 or 46 psi and held after turning the engine off and letting it sit for about ten minutes. Then I drove around some more and went to Autozone to get the battery checked. Battery came back 100% but when I went to crank it to check the alternator it didn't start the first time. It cranked the second time, though and the check engine light came on immediately (alternator tested good). Code was P1391 which I think means camshaft or crankshaft position sensor. I do think it was weird that it happened while the battery tester was connected but the guy at the shop says he's seen that in a lot of cars so I don't know if that's normal on some vehicles or signs of a deeper issue. I do think that I should probably look at replacing those sensors, though.
 
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The next time the engine dies while driving or you cannot get the engine to start after the Jeep was driven; verify the tachometer needle is moving while cranking the engine.
IF the tachometer needle does not move then there is a good chance the problem is your CKPS.
You can test this theory IF the engine dies by pouring a small amount of water onto the CKPS which is located on the bell housing of the transmission.
Try cranking the engine and IF the engine starts; the problem is the CKPS.
This process of cooling the CKPS will only work for a while so you should purchase a replacement OEM CKSP (if you can locate one).
 
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IkariBattousai said:
If bumping the wiring is causing the CEL to throw codes that seems like an issue that I should be looking into on its own, right?
Click to expand...

For now drive it.

If it doesn't throw codes then it was probably bumping something.

If it fires off a code make note of the circumstances.

Lotta folks replace sensors or fire the parts cannon at things that don't need replacing...and often end up in worse circumstances...both because new parts are shit...and you've muddled the troubleshooting logic.

Do one thing at a time. Then be patient and observe and document. Scientific method.

-Mac
 
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That's a really good point. I'll keep working on it. The most frustrating part, as I'm sure we all know, is when these problems are so intermittent. This thing has cut out on me twice over the last two months and I just wish I could figure out how to reproduce it.
 
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The cut out happened again today. Just driving along and the engine went out. Check engine light came on. Hit the gas and nothing. A detail I did notice this time is that the tachometer kept reading 2000 RPM until I engaged the clutch pedal even though the engine wasn't running. Check engine light came on with the codes: P0351, P0353, P0352, and P1391. So ignition coil circuits A, B, and C, then the camshaft or crankshaft position sensors.

Really starting to think it's wiring but hoping someone else can give me another sanity check.
 
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IkariBattousai said:
The cut out happened again today. Just driving along and the engine went out. Check engine light came on. Hit the gas and nothing. A detail I did notice this time is that the tachometer kept reading 2000 RPM until I engaged the clutch pedal even though the engine wasn't running. Check engine light came on with the codes: P0351, P0353, P0352, and P1391. So ignition coil circuits A, B, and C, then the camshaft or crankshaft position sensors.

Really starting to think it's wiring but hoping someone else can give me another sanity check.
Click to expand...

Remove and check the (3) 32 pin ECU harness connector pins and clips for oxidation; firmly snap the connectors onto the ECU harness connector receptacles.
Trace the ECU wiring harness along the firewall behind the valve cover and closely inspect the split wire loom and wiring harness in the proximity of the right rear corner of the valve cover.
This is a known problem area where the threaded head stud will rub thru the split wire loom and wiring insulation causing the signal(s) from the sensors to the ECU to short to ground.
I placed an old spark plug boot over the threaded head stud to ensure this doesn't happen.
 
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Checked the ECU connectors and traced the wiring and everything seems to be in good condition. No exposed copper anywhere I can see. The only thing that looks like it could be iffy is the ground on the engine block is covered in gunk and oil. I will probably disconnect and clean that up really well today. After clearing the codes Saturday I drove around a bit more and on the way in to work yesterday I got the check engine again but this time it was only P1391 for the position sensor. Strange because I never actually have problems cranking it to start or anything.
 
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Alright I went ahead and cleaned the G105 ground because it seemed dirty from the outside and when I undid it, it actually seemed pretty clean where it mattered. I don't know if this is going to help anything or not. Got a check engine light this week for P1391 again and P0138 briefly, but P0138 cleared on its own the next time I hooked the reader up to clear them again. Wiring still all looks decent to me so unless there's an internal break somewhere I'm at a loss for troubleshooting. Is it about time I start looking at replacing the sensors? I'm also posting some pictures here of the ECU connectors because while they look good, I'm not 100% sure if this taping is from the factory and if it's not I'm wondering if it could be hiding some damage. Thanks to everyone for bearing with me so far as I try to figure this out.
IMG_1087.JPEG
 
Got out the multimeter and tried a simple static ground test on most of the major engine bay grounds last night and they all seem to be testing well. Again, I don't see any areas with exposed copper or even a lot of wear in the wiring loom. Are there any other wiring tests I should be looking at checking out? If not I'm going to look at replacing the crankshaft position sensor since looking down it the bay it does look kind of grody. I am trying to avoid pulling the whole harness and going through it, but I will if I have to.
 
I'd say it's a safe bet to throw a crank position sensor at it...I'd use a Napa Echlin or a Standard Motor Products.

Also possible and you might want to try this...pull your CPS and clean it up.

-Mac
 
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