Keeps throwing the p0341 CPS Code

[Slicks]

I think I have read every thread on the p0341 code and tried everything except a new wiring harness. The truck throws the code with or without the Smarty loaded in it. I tried a new cam sensor, I tried shimming the sensor away from the cam, unhooked the PAC Brake (one guy claimed his was causing the code to be thrown when the pump kicked on), put a stock sensor in place of the ROKKTECH, etc. The truck runs and starts ok, but does have a bit of a "timing rattle" under no load conditions, not bad, just a bit more than normal. The rattle seems to go away as soon as you put the engine under load (ie accelerating from 30-55 mph). Are there some tests I can do on the harness before just replacing it all? Ohm readings between the pins on the connector, or voltage readings? Thanks, in advance... . Jason

 

[JLandry]

Jason,



Here's a list of pin-out and electrical measurements you can take to try and pinpoint the location of the problem.



Sensor Pin - Description (Wire Gauge Color) - ECM Pin



1 - 5 Volt Supply (18ga Pk/Yl) - 54

2 - Sensor Ground (18ga Br/Or) - 32

3 - Sensor Signal (18ga Db/Gy) - 24



(See the attached pin-out diagrams. )



All checks are done with the ignition off.



Disconnect the sensor from the wiring harness.



Check for 900-1000 Ohms between pins 1 and 3 of sensor. If outside this, sensor is bad.



Leaving the sensor disconnected, also disconnect the ECM from the wiring harness.



Check for less than 10 Ohms for each circuit listed above in the wiring harness. Any higher than this and you could have a break in one of the wires.



Check for a resistance *greater* than 100 Ohms between the sensor signal circuit (18ga Db/Gy) and battery negative terminal. A resistance less than this indicates a short in the sensor signal circuit.



Check for a resistance *greater* than 100 Ohms between the sensor signal circuit (18ga Db/Gy) and the 5 Volt supply circuit (18ga Pk/Yl). A resistance less than this indicates the sensor signal circuit is shorted to the 5 Volt supply circuit.



Check for a resistance *greater* than 100 Ohms between the sensor signal circuit (18ga Db/Gy) and the sensor ground circuit (18ga Br/Or). A resistance less than this indicates the sensor signal circuit is shorted to the sensor ground circuit.



At the sensor connector, measure the voltage between the sensor signal circuit (pin 3 - 18ga Db/Gy) and the battery negative terminal. If GREATER [correction of a typo from earlier post] than 1 Volt is measured, the sensor signal circuit is shorted to voltage.



Reconnect the ECM to the wiring harness.



Once again at the sensor connector, measure the voltage between the sensor signal circuit (pin 3 - 18ga Db/Gy) and the battery negative terminal. If GREATER [correction of a typo from earlier post] than 1 Volt is measured, the ECM is bad internally and needs to be replaced.



Hope this helps.



John L.

 

[Wingate]

Here's something you might consider trying... . Get some 3 strand shielded cable from an electrical supply house and the proper connectors for both ends. Use shielded cable if at all possible due to the inherent noise that speed sensors induce into the electrical system. Make an external harness and run it from the suspect sensor directly to the ECM pin locations. If it corrects the issue, you will know its the harness. This troubleshooting trick works great unless the sensor supply or sensor ground is "shared" in the wiring harness with other sensors. In that case, all you can run externally is the signal wire. I've got atleast 20 various test harnesses made up for the Cats I work on... . sure saves some grief.

 

[JLandry]

This troubleshooting trick works great unless the sensor supply or sensor ground is "shared" in the wiring harness with other sensors. In that case, all you can run externally is the signal wire.

Unfortunately in this case both the 5 Volt supply wire and signal ground wire are shared by multiple circuits.



John L.

 

[Wingate]

I was afraid of that. . As ECM's are getting more and more complicated and having more inputs/outputs... the ECm gets pinned out pretty quick... We have went from A-2 to A-4 in just a couple years... Went from having 2 40-pin connectors, then 2 70 pin connectors, and currently at a 70 pin and 120 pin combination thats getting filled up pretty quick!!.

 

[Slicks]

Thanks for the posts, that is exactly what I was looking for, I know what I will be doing tomorrow. I will post back what I find. It has been intermittent, so it may not show itself right away. I have a hunch it may be a ground wire though.

 

[Slicks]

I couldn't find any problems with the wiring harness. Has anyone every seen an issue with a "walking" camshaft or a bent cam gear? This engine was in an accident that the timing cover was hit by the fan pulley. It had made contact with the cam gear. The timing cover was swapped out, but we didn't even think about the cam gear being an issue.

 

[JLandry]

Jason,



Has the engine always been throwing this trouble code since the accident or is this something that only started recently? If you clear it, does it return immediately or does it take awhile?



John L.

 

[Slicks]

Jason,



Has the engine always been throwing this trouble code since the accident or is this something that only started recently? If you clear it, does it return immediately or does it take awhile?



John L.

I bought the long block to replace mine(I melted some pistons in my original engine pushing to hard). The engine came out of a wrecked truck so I don't know what it was doing before. My original engine was never throwing this code, so unless I pinched some wires I guess I need to look into the cam issue. It is intermittent, when I clear the code it sometimes take 30 miles of driving before the CEL comes on. It has lit up the CEL on start-up once or twice, but lately it has been 20-30 miles of driving before it lights up????

 

[JLandry]

Jason,



Since the camshaft position sensor detects machined notches located in the rear of the camshaft drive gear, I suppose it's possible one or more of these notches somehow got damaged in the accident. If they weren't actually run into the block, maybe there are metal shavings (or some other metallic contamination) filling one or more of the notches thus confusing the sensor?



Do you think it would be possible to pull the sensor and inspect the notches using a mirror and a flashlight (with a helper slowly rotating the crankshaft)? Otherwise, I would guess you're looking at having to pull the camshaft drive gear in order to examine it.



John L.

 

[Slicks]

I might have to try to look at it with a mirror. It is weird, the more I drive it the less is seems to come on. Today every time the CEL came on I would clear the code and watch how long before the CEL came on again. The first time it went 46 minutes, the second time it went an 1:56 minutes. I am going to change the oil again in it tomorrow and see what it does from here on out. I didn't notice metal shavings on the sensor when I pulled it out before, and I have had it in and out at least 3 times.

 

[JLandry]

Jason,



Do you have a spare ECM you could swap out to see if maybe it might be the cause of the problem? Are you using the ECM that came with the accident engine or your original?



John L.

 

[Slicks]

My original ECM, and no I don't have one to swap out and try right now.