FAQ: P0341 Camshaft Position Sensor (Cam Sensor / Timing Chain)

Lots of variables mentioned. Be sure to make only one change at a time between recording results.

With all the work you've done (and I admit I didn't read back far enough), have you triple checked the plugs?

He mentioned he hasn't changed plugs at all during all this, just wires.

I looked over the plugs yesterday and they seemed alright, but if I can get some good misfire readings I'll check the plugs of the offending cylinders a little closer. They were also replaced in June.

Check them very closely for small hairline cracks in the insulators. Use a magnifying glass if you have one.
They can crack due to a few reasons.
1. Running bad spark plug wires for any length of time can cause plugs to develop hairline cracks due to the electrical stress of ignition wire with poor conductivity
2. Plugs can easily crack during installation without knowing it. They will in turn cause the plug wires to go bad. (vicious cycle).

Very good technical article and general ignition system data on Magncor's website regarding these issues.

Rickw wrote:

Check them very closely for small hairline cracks in the insulators. Use a magnifying glass if you have one.
They can crack due to a few reasons.
1. Running bad spark plug wires for any length of time can cause plugs to develop hairline cracks due to the electrical stress of ignition wire with poor conductivity
2. Plugs can easily crack during installation without knowing it. They will in turn cause the plug wires to go bad. (vicious cycle).

Very good technical article and general ignition system data on Magncor's website regarding these issues.

Thanks for the info, I wish i had looked closer yesterday. Oh well it's not too hard to pull em out again.

What spark plug gap are you running. I've set mine to .050" with good results.
From magnacor.com;
"After fitting a high-output ignition most people are tempted to widen spark plug gaps, and although the latest aftermarket ignition systems can easily cope with the extra voltage necessary to jump the larger gap, often the smaller diameter spark plugs used in most recent street engines will cause an engine misfire (usually at high RPM) after a few miles because the spark tends to track down the coating formed from combustion on the center electrode insulator in preference to crossing the widened spark plug gap. Also, wider-gap spark plugs will wear out prematurely. Owners of some modified street cars have found differences in acceleration response by altering spark plug gaps, but generally, if Magnecor Race Wires are used, the best response will be attained with a standard gap. Again, experimentation is always necessary."

Our cars have what can be considered a high output ignition system so reducing plug gap from the OEM settings, when using Autolite's, down to .050" is beneficial.
I am going to try .045" after getting a tuning software package to see if that setting is more beneficial. Extra Wide Gap's can cause arcing of the plugs, carbon tracking, and they will run hotter and have a better chance of developing hairline cracks in the insulator..
If you haven't already read Magnacor's site I would highly recommend it. I don't believe it is all marketing hype. I believe it to be accurate information on the workings of a proper ignition system and the phenomena involved. I'm not saying you need to buy their wires just read the technical info, I've found it to be a good refresher course if you will.

Good information, I run .055" gap which is what a lot of people on the various 3800 forums seem to run with my mods. It's just unfortunate that this problem occurred right when i had to go back to school so I barely have time to work on it. I'm home for the weekend but am tied up with family events etc. Hopefully I can get this figured out before winter break when it's -5* out and I can't do anything it would be nice if i just had to buy some new 104s...

Small update. Tested the wire from the ICM to PCM and found it to have infinite resistance so it seems the fault lies there. This wire was also the same one that gave Travis and Codith their Cam Sensor issues so it may be a good place to start looking for others when this code appears if the sensor itself is still functional. Next step is to splice in a new wire and see if i can clear the code.

I'll assume with infinite resistance between the ICM and PCM the car wouldn't run at all.?

Rickw wrote:

I'll assume with infinite resistance between the ICM and PCM the car wouldn't run at all.?

No its just the designated Cam Sensor wire which is one of many wires going from the ICM to PCM. I tested one of the other wires going to the PCM and found zero resistance in order to confirm the testing procedure.

I'll repost what I found:PO341 code, 1998 Riviera
I found a broken wire in connector c101, pin a7, black 18 gauge wire to the ignition module. The wire was broken inside the insulation so it looked like it was good from the outside. C101 is the big 72 wire connector near the trans dip stick and A7 is the black wire on the bottom left side of the connector. It's a tight squeeze but you have to cut the wire before and after the connector to jump around it. Test the connection first with a meter between the connector then after confirming the open, gently pull on the wire with a needle nose from the front of the connector, and look to see that the insulation stretches indicating that wire inside is broken from the stress of the weight of the harness.

tech408 wrote:

I'll repost what I found:PO341 code, 1998 Riviera
I found a broken wire in connector c101, pin a7, black 18 gauge wire to the ignition module. The wire was broken inside the insulation so it looked like it was good from the outside. C101 is the big 72 wire connector near the trans dip stick and A7 is the black wire on the bottom left side of the connector. It's a tight squeeze but you have to cut the wire before and after the connector to jump around it. Test the connection first with a meter between the connector then after confirming the open, gently pull on the wire with a needle nose from the front of the connector, and look to see that the insulation stretches indicating that wire inside is broken from the stress of the weight of the harness.

Excellent post - only one thing to add.

Because of where the wire is broken, another option is to repair the connection. Use a jeweler's screwdriver to back the terminal out of the connector. Using a small vise or a pair of vise grips to hold the terminal, spread the wire crimp open (or simply use another pair of needletip pliers to yank out the butt of the wire). Then take the pin back out to the car. If there is enough wire in the harness you can simply strip a bit and solder the terminal back on, then reinsert it into the connector using that jewelers screwdriver if needed. If there is not enough wire in the harness, then splice, solder and insulate a short length on sufficient to let you reattach (solder) the terminal back on and reinsert it into the harness. If you do the repair this way you MUST be careful not to distort or fatigue the terminal because if you do it won't re-insert, will break on reinsertion, or some other failure.

Don't get me wrong - I am NOT saying Tech408's approach is bad, because it is a standard and avoids the problems that can ensue if you attempt to repair the connector without the Kent-Moore equipment. Another advantage is that Tech408's approach makes it real easy to find later where a harness has been spliced, and yet another advantage is that terminals to be repaired properly at a convenient time/place in the future are real easy to find. It's a good field fix. However I think you all might benefit from being aware of this alternative in cases where it's an advantage to repair in such a way that the connector can be normally detached, unless you also plan to put a spade or bullet connector in your splice.

In the FSM the approach that is taught is to use a repair kit to replace the bad terminal - pin or socket - in the connector, which if you have the Kent-Moore kit is fairly easy. Problem is, the kit is a cathedral unto itself -- take a look

http://www.acdelcotechconnect.com/pdf/imtn_V11I404.pdf

https://gmspecialservicetools.spx.com/Documents/Promotions/GM08-195.PDF (with prices)

These silly kits cost a bundle - great for a busy busy repair shop but just not something in a journeyman's reach. Give you a hint - the complete kit lists for about $6,100.-

Again - excellent post.

Albertj

Ok just want to make sure that I'm testing the right wire and getting a correct readout from my ohm meter. I'm testing the black wire that is designated Camshaft Position Sensor input at pin 5 (shown in the chart below) at the PCM, and also testing the believed corresponding black wire at the ICM where the large connector is (shown in picture below) for circuit resistance. When it was tested in this fashion it returned an infinite resistance. Just need to know if this reading is true because the wire is bad or it read that value because its the wrong wire.

check for continuity between the point you highlighted and the large connector to the left of the brake booster on the firewall. the circuit starts at the CPS, then into the ignition module, out of the ignition module, into the connector on the firewall, out of the connector and finally into the ECM. Read the details from my original post. It describes the exact locations. Good Luck

tech408 wrote:

check for continuity between the point you highlighted and the large connector to the left of the brake booster on the firewall. the circuit starts at the CPS, then into the ignition module, out of the ignition module, into the connector on the firewall, out of the connector and finally into the ECM. Read the details from my original post. It describes the exact locations. Good Luck

Is my method inconclusive? It seems that the test you are calling for it very similar. I understand that your test will allow me to pinpoint the area of trouble but the planned solution was to splice in a new black wire near the ICM and route it along the passenger-side fender through the firewall to the PCM as turtleman did with his. I am in no way bashing your approach, just wondering how it differs

L67 wrote:

tech408 wrote:

check for continuity between the point you highlighted and the large connector to the left of the brake booster on the firewall. the circuit starts at the CPS, then into the ignition module, out of the ignition module, into the connector on the firewall, out of the connector and finally into the ECM. Read the details from my original post. It describes the exact locations. Good Luck

Is my method inconclusive? It seems that the test you are calling for it very similar. I understand that your test will allow me to pinpoint the area of trouble but the planned solution was to splice in a new black wire near the ICM and route it along the passenger-side fender through the firewall to the PCM as turtleman did with his. I am in no way bashing your approach, just wondering how it differs

I never looked at the pinout for the engine harness as it plugs into the firewall but you could check it from the ICM to there instead of the ICM all the way to the PCM inside. More than likely, the failed wire would be under the hood, rather than inside the car under the dash, but nothing's impossible.

To answer your original question, Matt, unfortunately the same reading of infinite resistance means it could be a broken connection in the wire or wrong wire just the same. It is important to be sure that you are looking at the right wire. It doesn't hurt to test other same color wires to be sure as I've found that my factory service manual actually said the wrong PCM connector.

If you have the pinout for the firewall connector, I would go head and check it to the ICM connector, like tech408 said. Don't forget to check between the actual cam sensor and ICM also! The trend for failure seems to be between the PCM and ICM but it's still entirely possible the problems right there.

turtleman wrote:

L67 wrote:

tech408 wrote:

check for continuity between the point you highlighted and the large connector to the left of the brake booster on the firewall. the circuit starts at the CPS, then into the ignition module, out of the ignition module, into the connector on the firewall, out of the connector and finally into the ECM. Read the details from my original post. It describes the exact locations. Good Luck

Is my method inconclusive? It seems that the test you are calling for it very similar. I understand that your test will allow me to pinpoint the area of trouble but the planned solution was to splice in a new black wire near the ICM and route it along the passenger-side fender through the firewall to the PCM as turtleman did with his. I am in no way bashing your approach, just wondering how it differs

I never looked at the pinout for the engine harness as it plugs into the firewall but you could check it from the ICM to there instead of the ICM all the way to the PCM inside. More than likely, the failed wire would be under the hood, rather than inside the car under the dash, but nothing's impossible.

To answer your original question, Matt, unfortunately the same reading of infinite resistance means it could be a broken connection in the wire or wrong wire just the same. It is important to be sure that you are looking at the right wire. It doesn't hurt to test other same color wires to be sure as I've found that my factory service manual actually said the wrong PCM connector.

If you have the pinout for the firewall connector, I would go head and check it to the ICM connector, like tech408 said. Don't forget to check between the actual cam sensor and ICM also! The trend for failure seems to be between the PCM and ICM but it's still entirely possible the problems right there.

I did check another wire using the PCM pin chart I have and it returned zero resistance, so i believe that the pin # given to me for the black wire is correct. However I will still check the firewall harness to make sure that it is correct.

Here's some more stuff (including fuller images of somethings i posted) that someone may find of use.

hopefully the problem will be fixed soon I'm the latest person to have a crack at fixing it (I'm also L67's older brother for any new members here) it's been helping me get my performance objectives done in my electrical class. (hopefully i do not end up with the other poor souls who couldn't fix it). The game plan is exactly what L67 said which involves the said wire splice. I'm just hoping the Car alarm does not throw another revolt like last week where it was set off by absolutely everything.

Well GMfan1111 tested my car is his auto electrical class today and found some continuity issues between the ICM and previously mentioned firewall connector in the black wire. So it seems that that wire problem. He ran out of time in his class so the wire splicing will have to wait until next week.

Well my brother and dad were working on my car back home and found this:

The arrow points to the end of the black CPS wire that is cut from the circled plug in the big connector behind the trans dipstick that was mentioned a few posts up. It must've been weak or frayed when i was doing the rocker install, and all of the movement of parts to access the back VC tore it apart.

Good find. Hopefully all your issues will be taken care of with this repair.

Good Work!
And thanks for taking the time to post the pics.

Bert