: Stumble and stall



83CADMAN
09-07-13, 04:06 PM
Too good to be true! 2k miles with no problems after head stud install. Wouldn’t you know it!
The engine stumbled a couple of times then stalled at a traffic light. It started up again but only after 2nd try. By the time I got it home, (about ¼ mile) the “SERVICE ENGINE SOON” light came on. I checked for codes and what came up was “P083”, “Crankshaft to Ignition Module Failure”.
Being the novice mechanic that I am, confusion is my first response.:confused: Before I start throwing cash at it I thought it beneficial to seek direction from this forum. It has been most helpful in the past. So Please, any clarification to remedying this condition would be most helpful.

Submariner409
09-07-13, 04:39 PM
Which car ?

If it's the '94 (?? Northstar ??), I would suspect either a bad ICM (Ignition Control Module)(coil pack base) CMP connector or a bad ICM-to-engine ground wire.

83CADMAN
09-07-13, 09:32 PM
Which car ?

If it's the '94 (?? Northstar ??), I would suspect either a bad ICM (Ignition Control Module)(coil pack base) CMP connector or a bad ICM-to-engine ground wire.

Yes its my 94 N*. This is the N* forum?
Thanks for the diagram.
I was underneith checking connections and noticed the crank sensor (CMP?) connector was wet from frost melt off the A/C comp and / or covered with oil. could this be the culprit. I tightened the sensor and stopped the minute oil drip. I did have this engine out of the car and that particular connection was disconected. I'll go back under and clean it up, clear the code & see what happens.

Ranger
09-07-13, 11:23 PM
CMP = Camshaft Position sensor
CKP = CranKshaft Position sensor.

83CADMAN
09-08-13, 10:38 AM
Thanks Ranger for the acronyms and their definitions.
In post#3, I was referring to my visual inspection of the crankshaft position sensor, (CKP) and its electrical connector. My confusion over acronym was based upon the reference to “CMP connector" made by Submariner409 in post #2.

Sub, why would the camshaft position sensor (CMP) be suspect?

Submariner409
09-08-13, 05:14 PM
The CKP's are the ignition and fuel injector triggers. The CMP is the primary cylinder TDC reference to the PCM - and all those pulses flying around are what gets everything to spark and spray at exactly the right instant.

More acronyms in the sticky just above this thread.

The CMP is located in the front (passenger end) of the right (rear) cylinder head directly in front of the exhaust cam sprocket - it's tripped by a small bulge dot in the sprocket face - Hall effect. The connectors sometimes get corroded or loose - or the CMP itself loses continuity in the magnetic trigger coil.

83CADMAN
09-08-13, 07:13 PM
OK! It could be this or it could be that or it could be that other thing. I get it! I could have picked up a Chilton.

Ranger
09-08-13, 08:43 PM
Don't waste your money on Chilton or Haynes. If you want a service manual I would strongly recommend A FSM by Helm Inc. Ebay is your friend.

83CADMAN
09-09-13, 12:24 PM
I have a FSM.

Ranger
09-09-13, 02:53 PM
Oh, I just went back and reread post #7............................ and just got it. :duh:

83CADMAN
09-09-13, 04:20 PM
That OK Ranger, I went back into my FSM and discovered what I was looking at and fiddling with in post #3 was in fact the oil level sending unit. Like I said before, “Being the novice mechanic that I am, confusion is my first response”.
So after a couple of hours with my FSM I did find information concerning the crankshaft sensors tucked up behind the engine mount and exhaust manifold. I can bearly see them much less get my hand in there.

This is the kind of heads up I was looking for on this forum.
1. Remove lower splash guard
2. Remove upper splash guard
3. Remove front upper engine mounts from bulkhead
4. Remove air filter box
5. Remove cooling fans
6. Install lifting device to engine
7. Remove front lower engine mount and brace

This is to just gain access to the sensors in order to check / remove / replace.
Plus the cost to replace them is around $60 each.
If I have to go to that length to access them replacement of both sensors are warrented.
For $120 I would like to be sure so I’m gona brave this again;

Question:
Is there a way to test the sensors without going to the extreme listed above. Shop tricks, anything?

Ranger
09-09-13, 09:26 PM
I just replace my CKP sensors last summer. No need for all that BS. You will need a looong extension, a universal joint and a set of metric sockets. Remove the lower air deflector. Remove the oil filter and then the filter adapter (3 long bolts). That will give you the clearance you need to get at the CKP sensors. It's still gonna be tight and you'll still curese the designing engineer, but it's doable (MUCH easier if you can get access to a lift).

I think I paid $77 for both (incl shipping) from Amazon.

Not sure how you would go about testing them (or if you even can). Mine would fail intermittently and rarely, but I knew the symptoms so I just changed them.

83CADMAN
09-10-13, 10:34 AM
I just replace my CKP sensors last summer. No need for all that BS. You will need a looong extension, a universal joint and a set of metric sockets. Remove the lower air deflector. Remove the oil filter and then the filter adapter (3 long bolts). That will give you the clearance you need to get at the CKP sensors. It's still gonna be tight and you'll still curese the designing engineer, but it's doable (MUCH easier if you can get access to a lift).

I think I paid $77 for both (incl shipping) from Amazon.

Not sure how you would go about testing them (or if you even can). Mine would fail intermittently and rarely, but I knew the symptoms so I just changed them.

All right! Information I could have used.
I found both CKP sensors and a oil pressure unit at Auto Zone, all for $70 and decided to replace them. Out of frustration I tore into it yesterday, and of course I pulled the fans and engine mount. I got the job done, it was a …, and I’m not sure yet if it fixed the problem. Today I guess I’ll drive around, waste gas to see if it kicks a code. I need this car to go out of town later this week.
Damn, I didn’t think to pull the oil filter!!!!!

Ranger
09-10-13, 09:48 PM
Too bad you didn't check in first. We would have told you to stay away from those cheap unreliable AZ Don'tLast parts. They may be guaranteed for life, but how many times do you want to do that job.

83CADMAN
09-11-13, 11:51 AM
Too bad you didn't check in first. We would have told you to stay away from those cheap unreliable AZ Don'tLast parts. They may be guaranteed for life, but how many times do you want to do that job.

Ummmm! I think I did check in first. Post number 1, PCM fault code!

All the advice I got was about acronyms and CAMshaft sensor!
The next time I’ll remove the oil filter and adapter and shop elseware for parts, thank you very much. Compared to the route I took it should be a simple task.
By the way, sensor replacement fixed the problem.

Ranger
09-11-13, 02:49 PM
Ummmm! I think I did check in first. Post number 1, PCM fault code!
No, I meant before using an AutoZone part. At least if you have the same symptoms in the future you'll know what it is. The second time around is always faster.

83CADMAN
09-25-13, 03:35 PM
The haunting infamous DTC from hell…P083!
I’ve read countless post concerning DTC P083 “Crankshaft to Ignition Module Failure”.
From horror on the freeway as the engine just stalls in traffic, to almost new everything and still…P083! With sensors at $100 ea at GM and ICM’s running upward of $300. Frustrations galore!
My story is pretty much the same. I started with installing new crankshaft position sensors. Man what a learning experience that was! Anyway I logged about 200 miles before IT returned. Into the shop to pull the sensors and take them back to AZ for a new pair. Got them installed, went very easy this time. I was able from on my back under the pass side, reach my arm up and through with my fingertips touching the CKP’s. Cleared the code, started er up and DAMNIT! P083. Now let me mention, each time I worked on this car I would test drive it, at approx 2 to 3 miles the thing would either stumble or stall, and each time it would start right back up.
SOUND FAMILURE?

What I eventually discovered to be the problem is humbling.
After checking out the ICM with no change, I pulled the wire harness enough to get to the CKP’s leads. I started to unwrap the tape and lo to my surprise, someone had shaved the wires a little for testing and just wraped some tape. When the cooling fans kicked on (@ abt 2 mls) the wire harness would move a little, just enough for them to short. I found all the sensors wires compromised and needing repair. Instead of re-wraping with regular tape I used "Liquid Electrical Tape" to form a new insulative jacket around the bare wires. CHEAP FIX!
The lesson here is;
Before you start spending big bucks changing out parts, check the wires close to their ends under the tape for the last service tech’s handy work.

Submariner409
09-25-13, 05:52 PM
Before you start spending big bucks changing out parts, check the wires close to their ends under the tape for the last service tech’s handy work.

Post #2.

83CADMAN
09-26-13, 12:40 PM
Post #2.
What?
Post # 2?
What??
You referred to the CAMshaft sensor, connectors and the ICM as your suspected culprits.
All, which didn’t come close to helping me, a self, proclaimed novice mechanic, (re: post #1) who was seeking HELPFUL information.
If anything you added more confusion to the mix and when I asked you for simple clarification I got nothing. Re:Post#6
You see, I followed your advice, I checked the “CMP” CAMshaft position sensor, I checked all the connectors, I ran a voltmeter test on the wires. I pulled the ICM / COILS and had it tested, I checked and replaced ground cables. All “GOOD” and still the intermittent DTC P083!
Ranger is the one who I’ll give a star to for his pointing to the proper device, “CRANKshaft position sensor), as suspect.
But wait, it wasn’t the CKP’s! I put back in my old ones and returned the new ones.
After all that and a lot of time, I FIGGURED OUT THE FIX! Not you.
“REPAIR THE INTENTIONAL DAMAGE TO THE SENSOR WIRES CAUSED BY A PREVIOUS SERVICE TECH AND BURIED IT UP INSIDE THE HARNNES”.
Maybe my discovery will help some other novice “CADILLAC OWNER & ENTHUSIAST”, like me, in resolving the frustrating intermittent DTC P083 so many before have sought advice from this forum with no avail.
Post #2! Really?

Submariner409
09-27-13, 09:37 AM
Post #2 referred to checking the ICM and connectors - Sorry I didn't specifically list the CKP's in the text, but the picture does. Whatever. You found the problem - carry on.

83CADMAN
09-27-13, 10:55 AM
The point here is to inform fellow Cadillac owners of fixes to common problems.
The discovery of stripped sensor wires, taped up and contained in the harness loom, out of sight of a visual inspection, where they can deteriorate/twist causing an intermittent short in the circuit as the cause of a very common intermittent DTC P083. $$$ SERVICE ENGINE SOON $$$ certainly qualifies.

Yes I found the problem and fixed it and I’m sharing the results with others.
I reiterate, before you start replacing expensive parts, pull back the electrical tape when performing a visual inspection of the connectors.


Post #2 referred to checking the ICM and connectors - Sorry I didn't specifically list the CKP's in the text, but the picture does. Whatever. You found the problem - carry on.

I appreciate the wiring diagram you posted, but my FSM has the same information and so does Chilton.
What you, the FSM or anyone else for that matter did not mention was, the common service practice of exposing wires by stripping their jacket to perform a CKP circuit test procedure and then conceling it in the harness.
Whatever? Carry on?