CPS failure symptoms?

Gary - K7GLD · 05-12-2006, 06:31 PM

What are the symptoms of a weak CPS in the '02 engines?

Not an outright failure, but random "misses' in picking up the signal, probably increasing as RPM increases?

Is the CPS adjustable for gap - or a simple pull and replace?

Does the CPS have any effect on the VP-44, is it capable of causing a VP-44 P0216 code if it generates weak or occasionally missing pulses?

PRout · 05-12-2006, 11:42 PM

Mine recently kicked the bucket.. First symptom was while idling at a light it stumbled for a second and got a CEL. Did it again about a week later, and noticed the tach dropped to 0 when the motor stumbled, CEL again. Checked codes - 336 (or something close to that). Replaced CPS, problem gone.

Note: One time it wouldnt start (in a drive-thru of course).. Noticed the fuel pump wasnt going on either.. Waited a few seconds, and re-tried, and it fired up, FP was running again.. I think the CPS signal tells the ECM to run the fuel pump.

Note: Not sure what the difference is between my 2000 and your 2002 model though. Had heard it was called a Crankshaft Position Sensor, and possibly renamed to a Camshaft Position Sensor. Dont know that for sure. Dont know if the part is the same either.

It is a pull & replace part, and not user servicable.

Gary - K7GLD · 05-13-2006, 01:22 AM

Thanks for the info - I think the earlier Crankshaft sensors were mounted to the rear of the engine near the starter - later Camshaft sensors are on the front where the VP-44 provides a nasty blockage for getting to it.

My truck runs fine under all driving situations - but a stalled LP 6 months or so back caused an engine hiccup, and delivered a CES light and CPS error code - I would have more expected a P0216 from that, since that was the first and last CPS code I've ever seen.

NOW, I can generate a P0216 anytime I want, by reving the engine to 3000 RPM in neutral and holding it there for 10 seconds or so. I detect a mild random miss when I do this, along with fluctuation in the tachometer - and not sure whether the larger injectors, or other system sensor issues might cause the same thing.

Just regular driving and towing are fine, no funny engine behaviors or codes - and lots of power and good economy.

I suppose I'm living in denial as far as the VP-44 is concerned, but really want to make dern sure I'm treating the right problem and not a decoy...

That's why the question as to the effects of a weak or erratic CPS, as compared to an outright failure, and how/if it might relate to a P0216 code.

Defective CPS = $70 at NAPA
Rebuilt VP-44 = $1000+ at most any rebuilder...

PRout · 05-13-2006, 02:43 AM

Quote:

Originally Posted by Gary - K7GLD

really want to make dern sure I'm treating the right problem and not a decoy...

That's why the question as to the effects of a weak or erratic CPS, as compared to an outright failure, and how/if it might relate to a P0216 code.

Defective CPS = $70 at NAPA
Rebuilt VP-44 = $1000+ at most any rebuilder...

Absolutely..

Also, I know I saw a link to a site that had CPS's for something like 35 bucks, as well as other popular Cummins replacement parts. Couldnt find the site again when I needed one so paid full price from Dodge. (83.00)

Maybe someone can repost the link..

PRout · 05-13-2006, 02:51 AM

Its too bad the Smarty doesnt have a feature to tell the ECM to ignore a 216 code. Seems like seeing the code is worse than the disease (if there arent any drivability issues).

Back to the topic.. Can a CPS cause a 216 code??

Jefff929 · 05-13-2006, 04:56 AM

mine did

Gary - K7GLD · 05-13-2006, 04:56 AM

Quote:

Originally Posted by Shortshift

Its too bad the Smarty doesnt have a feature to tell the ECM to ignore a 216 code. Seems like seeing the code is worse than the disease (if there arent any drivability issues).

Back to the topic.. Can a CPS cause a 216 code??

Exactly!

If I didn't have that dern light on the dashboard, I'd be happy as a clam - but since it IS there, all I can do is assume and fear the worse...

As it stands, unless late info points me in another direction, the new VP-44 will go in Sunday...

mhenon · 05-16-2006, 02:08 PM

Gary, is the CPS on the '02 behind the VP? I thought this was an easy swap-out but it sounds like the VP must be pulled to get to the sensor.
Can it be removed at all with the VP in place?
Mike

nps · 05-16-2006, 03:35 PM

Quote:

Originally Posted by mhenon

Gary, is the CPS on the '02 behind the VP? I thought this was an easy swap-out but it sounds like the VP must be pulled to get to the sensor.
Can it be removed at all with the VP in place?
Mike

The VP doesn't have to be removed - just a whole lot easier if it is already out.

Gary - K7GLD · 05-16-2006, 04:10 PM

Quote:

Originally Posted by mhenon

Gary, is the CPS on the '02 behind the VP? I thought this was an easy swap-out but it sounds like the VP must be pulled to get to the sensor.
Can it be removed at all with the VP in place?
Mike

I've not looked at it closely from under the truck, where you would have to do the change - I'm sure it can be done without pulling the VP, but a contortionist with small hands and arms would surely help! The sensor itself is just below the VP, and slightly inboard toward the engine.

It's easy to follow the wiring harness to find it's location, but the retaining clip is on the topside and VERY stout - need a good strong set of fingers to get mine released.

I have some other work to do under the truck today, and will look closer at the CPS from there, and take a picture if I can get a clean shot at it...

SSabick · 05-16-2006, 04:25 PM

Ok, so if the check engine light isn't on, but you get the p0216 code when you turn the key 3 times, does this just mean a CPS failure. I had a stumble once, and got the code when I cycled the key 3 times, but I still don't have the check engine light. I still have pretty good power, and the only real difference is the light grey smoke instead of the dark black smoke that I am used to. I had the stumble only once, and it hasn't showed up since. This was about a month ago. The code is still there, but still no check engine light. Worst part about it, I still seem to have alright fuel pressure. I guess that I was just one of the lucky ones with a bad 2002 VP.

nps · 05-16-2006, 04:28 PM

Quote:

Originally Posted by SSabick

Ok, so if the check engine light isn't on, but you get the p0216 code when you turn the key 3 times, does this just mean a CPS failure.

Nope - it means the VP44 or you had some air in your lines.

Quote:

Originally Posted by SSabick

I still have pretty good power, and the only real difference is the light grey smoke instead of the dark black smoke that I am used to. I had the stumble only once, and it hasn't showed up since. This was about a month ago. The code is still there, but still no check engine light. Worst part about it, I still seem to have alright fuel pressure. I guess that I was just one of the lucky ones with a bad 2002 VP.

Congratulations. You are one of the lucky ones. Get ready to change it.

Gary - K7GLD · 05-16-2006, 04:59 PM

Quote:

Originally Posted by SSabick

Ok, so if the check engine light isn't on, but you get the p0216 code when you turn the key 3 times, does this just mean a CPS failure. I had a stumble once, and got the code when I cycled the key 3 times, but I still don't have the check engine light. I still have pretty good power, and the only real difference is the light grey smoke instead of the dark black smoke that I am used to. I had the stumble only once, and it hasn't showed up since. This was about a month ago. The code is still there, but still no check engine light. Worst part about it, I still seem to have alright fuel pressure. I guess that I was just one of the lucky ones with a bad 2002 VP.

I had pretty much the same experience as you describe over 2 YEARS ago, with no further incidents until the last few weeks, when the codes again showed as I was doing other fuel system changes. I would have written them off as simply air in the lines - but I started also getting them during regular driving situations, tho' the engine is operating perfectly.

I couldn't take a chance due to the RVing season being here and a 2000 mile trip starting a week from today, so I swapped out the VP Sunday.

Gary - K7GLD · 05-16-2006, 08:04 PM

AS promised, here's a pic of that dern CPS taken from underneath the truck - it's in that red circle.

If the vacuum pump tubing is removed or swung outta the way, shouldn't be too hard to change - the wiring bundle to the CPS is pretty long, and the plug can probably be removed after the CPS is removed and pulled down below.

There's only a single 8mm (as I recall) bolt holding it in place, and barely visible to the left of the CPS body...

Bob4x4 · 05-16-2006, 08:14 PM

Quote:

Originally Posted by Gary - K7GLD

AS promised, here's a pic of that dern CPS taken from underneath the truck - it's in that red circle.

If the vacuum pump tubing is removed or swung outta the way, shouldn't be too hard to change - the wiring bundle to the CPS is pretty long, and the plug can probably be removed after the CPS is removed and pulled down below.

There's only a single 8mm (as I recall) bolt holding it in place, and barely visible to the left of the CPS body...

Be prepared to find a small torx bit...........and have a magnet handy so you don't risk loosing the bolt.

Bob