CPS failure symptoms?

[T Peterson]

Is there anything other than the VP that could be removed to gain better access?
TIA

Tom

[Gary - K7GLD]

Originally Posted by T Peterson

Is there anything other than the VP that could be removed to gain better access?
TIA

Tom

I don't think so - the VP-44 seems to be the primary obstacle.

By the way, since this is an old thread resurfaced, I now have about 15K miles on the rebuilt II VP-44 - never ANY related codes, and the OEM CPS is still installed - no codes other that the couple earlier related, 40K miles and 5 years or so back...

Glad I didn't replace it...

[T Peterson]

Good news Gary, I'm still hoping the code I pulled, P0341 if I remember correctly, is truly the culprit and I don't have an APP's going out or worse, the VP. Thanks for the reply, by the way the CPS I bought was $38.

Tom

[willyslover]

just a lil note to this.. don't assume napa is lower priced than Cummins

I bought one at Napa [while shopping for another sensor [map] , napa was out of the map so off to Cummins I went. while there asked the parts man the price of this sensor and they were ~$15.00 lower than Napa...so a call is worth the time

[PRout]

Question from the past..

Am I correct in that if the Camshaft Position Sensor is totally dead (broken wire) the truck will not start or run?
Bob Weis

Originally Posted by PRout

Note: One time it wouldnt start .... Noticed the fuel pump wasnt going on either.. Waited a few seconds, and re-tried, and it fired up, FP was running again.

Due to the occurrence mentioned above, I "suspect" at least under certain conditions, if the cps dies, the engine wont run. I know for a fact that this truck runs with no fuel pressure..
This is referring to a year 2000 truck that has the sensor mounted down by the crank, not up by the cam.

[T Peterson]

Well, it's not the CPS. I took it to a trusted mechanic to replace the cps and it still threw the same code, they checked the wiring between the cps and the ECM and said it was good, so they said it must be the ECM, so I bought an ECM from Bob Wagner (thanks Bob) replaced it and the same fricken thing. Here are the symptoms, start cold, drive for 4 to 6 minutes then tach dies and 2 seconds later I lose power (not limp mode I think, I can still go 70 or so but not uphill and very little acceleration) then 4 or 5 minutes and tach comes back, 2 seconds later power returns and all is fine until the next cold start. Anyone have any ideas? At first I thought it might be a bad ground but symptoms are so predictable, could it be heat related. Any and all ideas welcome. TIA

Tom

[Gary - K7GLD]

Originally Posted by T Peterson

Well, it's not the CPS. I took it to a trusted mechanic to replace the cps and it still threw the same code, they checked the wiring between the cps and the ECM and said it was good, so they said it must be the ECM, so I bought an ECM from Bob Wagner (thanks Bob) replaced it and the same fricken thing. Here are the symptoms, start cold, drive for 4 to 6 minutes then tach dies and 2 seconds later I lose power (not limp mode I think, I can still go 70 or so but not uphill and very little acceleration) then 4 or 5 minutes and tach comes back, 2 seconds later power returns and all is fine until the next cold start. Anyone have any ideas? At first I thought it might be a bad ground but symptoms are so predictable, could it be heat related. Any and all ideas welcome. TIA

Tom

Sounds like a possible alignment/gap issue between the tone ring and CPS sensor, causing an erratic or irregular signal to the ECM - a good real-time code reader/analyzer might show exactly what is going on - at least the Actron 9145 I use allows monitoring sensor inputs as the engine is running...

[JLandry]

Originally Posted by T Peterson

Well, it's not the CPS.

...so I bought an ECM from Bob Wagner (thanks Bob) replaced it and the same fricken thing.

Any and all ideas welcome.

EDIT: I mistakenly read the P0341 diagnostic procedures for a gasoline engine equipped truck and tried to lead Tom down the wrong problem solving path... until he caught it when I emailed him the procedures and wiring diagram for the CPS.

Sorry 'bout that Tom!

Back to square one...

John L.

[T Peterson]

Thanks guys, good info, looks like I'll have to talk with my guy. I do trust him but not everybody can know everything about everrything. I'll arm him with this info and let him give it another try. I'll keep y'all updated. In the mean time I'll see if I can scratch up enough poker money to get a reader like Gary's

Tom

[JLandry]

EDIT: Irrelevant information to Tom's situation given... see post #38.

John L.

[T Peterson]

You're right, pm sent.

Tom

[JLandry]

Originally Posted by T Peterson

Here are the symptoms, start cold, drive for 4 to 6 minutes then tach dies and 2 seconds later I lose power (not limp mode I think, I can still go 70 or so but not uphill and very little acceleration) then 4 or 5 minutes and tach comes back, 2 seconds later power returns and all is fine until the next cold start.

Tom,

When this low-power event happens, does it happen every single time you operate the truck... or only occasionally?

Does the tachometer stay dead (which I assume means reading zero rpm) during the entire low-power event? If it does remain at zero, it seems to me like it's got to be a heat-related intermittent loss of the CPS signal to the ECM just as the trouble code indicates.

Did the mechanic carefully check the wiring harness, the CPS connector, and the appropriate ECM connector pins when the engine has been warmed to point where the low-power event occurs?

Thanks,

John L.

[JLandry]

Tom,

A couple more questions:

Does your truck have an automatic transmission?

When you encounter the low-power event, do you notice smoke coming from the tailpipe? If yes, what color and how much?

Thanks,

John L.

[T Peterson]

Tach stays on zero the entire time of low power. I agree it seems to be heat related, as for the wiring being checked thoroughly, I can only take his word on it, but it just doesn't sound like wiring because it is so predictable (see previous post). As for pins on the ECM, this is the second ECM with the exact same symptoms This one is beyond me. Thanks again for all the brain power going toward my problem. It is a 6 speed 01. I haven't noticed any smoke but I really haven't been looking for it. When I go home today I'll check for it.

Tom

[JLandry]

Originally Posted by T Peterson

Tach stays on zero the entire time of low power. I agree it seems to be heat related, as for the wiring being checked thoroughly, I can only take his word on it, but it just doesn't sound like wiring because it is so predictable (see previous post). As for pins on the ECM, this is the second ECM with the exact same symptoms This one is beyond me. Thanks again for all the brain power going toward my problem. It is a 6 speed 01. I haven't noticed any smoke but I really haven't been looking for it. When I go home today I'll check for it.

Tom,

When I asked about pins or connectors, I was thinking along the lines of maybe there's a problem with one or more of the "sockets" inside the connector(s) on the ECM or CPS wiring harness not making good contact. It's a long shot to be sure, but has happened.

I'll bet you could nail down where the problem is coming from if you had a Chrysler DRBIII Scan Tool hooked up when the low-power event happened. The DRBIII would show you the sensor inputs and outputs in both the ECM and PCM in real time. You could then see which computer might be missing either a camshaft or a crankshaft position signal. The DRBIII lab scope function could also be used to monitor the CPS output wire to check the signal quality for irregularities.

Assuming there's nothing wrong with the CPS, the ECM, or the wiring harness between the CPS and ECM, I'm wondering if maybe the PCM or it's wiring harness could be faulty? I suggest this because the PCM gets a crankshaft position signal from the ECM over a dedicated line, and what if the PCM stopped reading this information for some reason when it gets hot? I know you'd loose the tachometer signal for sure, and I'm guessing it's possible the PCM could be sending signals back to the ECM (over the CCD bus) telling the ECM to limit power due to a drivetrain problem. One way to rule this out would be to monitor the sensor signals with a DRBIII.

At this point it might help to bring the truck to a good Chrysler dealer who'll hook up a DRBIII and go for a test drive with you to look for causes.

John L.