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Discussion Starter #1
A few weeks ago, my 2002 Intrepid w/ 2.7 engine started bouncing off the rev limiter above approx 2,000 RPM. In the past, this indicated a failure (complete or intermittent) of the cam position sensor. The computer would "fake" the ignition timing using output from the CRANK sensor, but limit engine speeds as a safety precaution (and to remind owners to fix the ^!%^ problem).

The same problem had occurred previously, but disappeared when I installed a new sensor. However, after about a year, the problem came back.
So I just bought a replacement, installed, and the problem didn't go away. (The battery was disconnected while doing this, so any codes should have been cleared.) I think it's fairly unlikely that the semi-new and new sensors are both defective, so it's some other problem. (BTW, sometimes the computer throws an OBD-II code for the sensor circuit (same code for intermittent or failing); sometimes it doesn't -- behavior that's also not unusual.)

Using a VOM to test the unplugged connector w/ the ignition turned on:

--ground is good, though a voltage drop of approx .2 volts seems slightly high. (In the past 1-2 years, I've inspected and cleaned all engine and body grounds that I can find in the engine compartment.)
--the circuit providing power to the sensor seems about right, approx 4-6 volts (can't remember).
--however, the circuit returning the sensor output to the engine computer also shows the same 4-6 volts. Shouldn't it be zero, or close to it?

I haven't yet performed rigorous "wiggle" tests on the wiring to see if the results vary, but my informal tests previously didn't show any difference.

However, Dorman sells a kit (which I purchased) that includes a new cam sensor, plus a new connector w/ pigtails for splicing to existing wiring. This suggests that the connector wiring has been problematic (as otherwise, why would anyone make a kit to replace it?)

So, possibilities include:
1) bad connector and nearby wiring, which the kit should fix.
2) wiring problem elsewhere in the circuits (most likely the return signal to the computer).
3) a short somewhere between the hot supply wire and the signal wire (if both are showing the same voltage).

Any thoughts?

BTW, neither of the sensors are Mopar, but the brand-new one is from Dorman's "premium" line. I know some of you are "Mopar all the way," but the cam sensor is dead simple -- basically, a magnet. The technology is similar to ABS sensors, which rarely fail, despite being in locations that are exposed to rain, flying gravel, etc.

Thanks for any assistance!
 

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oem is the only wy to go with sensors on these cars.
seriously.
anytime people come looking for help, it's 99% of the time a non oem sensor that is still a problem.
 

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Woober Goobers!
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For Cam/Crank sensors.....OEM is the only way to go. Plenty of posts where the aftermarket sensors didn't work out of the box or failed shortly after. And one thing to consider is the environment the sensor is in as in engine heat/large temperature changes.

To do any meaningful diagnosis on the Cam sensor you need to put a scope on it to analyze the waveform. A voltage reading alone isn't going to cut it other than to verify the sensor source voltage.

For the camshaft position sensor:

Pin 1 Violet/White Stripe....5 volt Sensor Supply
Pin 2 Black/Brown stripe is the Sensor ground. It's important to know that this ground is provided by the PCM and not a chassis ground.
Pin 3 Tan/Yellow stripe is the Sensor Signal back to the PCM. You would need a DRB or scope to accurately verify/monitor this signal.
 

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You haven't indicated whether you have any codes? Do you and what are they?

Assuming you have a P0340 code....

Symptom:
P0340-CAMSHAFT POSITION SENSOR CIRCUIT

When Monitored and Set Condition:
P0340-CAMSHAFT POSITION SENSOR CIRCUIT
When Monitored: Engine cranking/running. Battery voltage greater than 10 volts.
Set Condition: At least 5 seconds or 2.5 engine revolutions have elapsed with crankshaft
position sensor signals present but no camshaft position sensor signal. One Trip Fault.

POSSIBLE CAUSES
INTERMITTENT CRANKSHAFT POSITION SENSOR SIGNAL
INTERMITTENT CAMSHAFT POSITION SENSOR SIGNAL
(K6) 5 VOLT SUPPLY CIRCUIT SHORTED TO GROUND
(K6) 5 VOLT SUPPLY CIRCUIT OPEN
(K6) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
(K44) CMP SIGNAL CIRCUIT SHORTED GROUND
(K44) CMP SIGNAL CIRCUIT OPEN
(K44) CMP SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K44) CMP SIGNAL SHORTED TO (K6) 5 VOLT SUPPLY CIRCUIT
(K4) SENSOR GROUND CIRCUIT OPEN
PCM - (K6) 5 VOLT SUPPLY
PCM - (K44) CMP SIGNAL
CAMSHAFT POSITION SENSOR

And as you can see first on the list of possible causes is an Intermittent Crankshaft Position Sensor. It's possible your Camshaft Sensor is OK and the Crankshaft position sensor is the problem or it's associated wiring.
 

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There's always JJI !
 

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The technology is similar to ABS sensors, which rarely fail, despite being in locations that are exposed to rain, flying gravel, etc.
funny you say that. i replaced a front hub on a gm pick up with sensor.
took it out for a test drive and the abs light is on.
scan it, and it's the sensor for that wheel.
ordered a new one, in case the hub shipped one is faulty, and it won't work either.
dig the old hub out of steel recycling and take out the old sensor and installed it, and light out.
no, they are not all the same.
 

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Discussion Starter #7
funny you say that. i replaced a front hub on a gm pick up with sensor.
took it out for a test drive and the abs light is on.
scan it, and it's the sensor for that wheel.
ordered a new one, in case the hub shipped one is faulty, and it won't work either.
dig the old hub out of steel recycling and take out the old sensor and installed it, and light out.
no, they are not all the same.
You haven't indicated whether you have any codes? Do you and what are they?

Assuming you have a P0340 code....

Symptom:
P0340-CAMSHAFT POSITION SENSOR CIRCUIT

When Monitored and Set Condition:
P0340-CAMSHAFT POSITION SENSOR CIRCUIT
When Monitored: Engine cranking/running. Battery voltage greater than 10 volts.
Set Condition: At least 5 seconds or 2.5 engine revolutions have elapsed with crankshaft
position sensor signals present but no camshaft position sensor signal. One Trip Fault.

POSSIBLE CAUSES
INTERMITTENT CRANKSHAFT POSITION SENSOR SIGNAL
INTERMITTENT CAMSHAFT POSITION SENSOR SIGNAL
(K6) 5 VOLT SUPPLY CIRCUIT SHORTED TO GROUND
(K6) 5 VOLT SUPPLY CIRCUIT OPEN
(K6) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
(K44) CMP SIGNAL CIRCUIT SHORTED GROUND
(K44) CMP SIGNAL CIRCUIT OPEN
(K44) CMP SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K44) CMP SIGNAL SHORTED TO (K6) 5 VOLT SUPPLY CIRCUIT
(K4) SENSOR GROUND CIRCUIT OPEN
PCM - (K6) 5 VOLT SUPPLY
PCM - (K44) CMP SIGNAL
CAMSHAFT POSITION SENSOR

And as you can see first on the list of possible causes is an Intermittent Crankshaft Position Sensor. It's possible your Camshaft Sensor is OK and the Crankshaft position sensor is the problem or it's associated wiring.
Thanks for the replies. I should have clarified that the voltage measurements were made with the sensor disconnected from the harness -- so whether the sensor was good, bad or indifferent wouldn't affect the readings. Looking at the possible causes listed, it seems like a signal circuit shorted to supply voltage is the most likely culprit.

One further note about the OEM vs. aftermarket parts discussion: I know there are crummy parts out there from no-name sources. But Dorman, for example, has been around since 1918, and its catalog lists more than 40,000 products. Sales volume to do-it-yourselfers through auto parts stores or eBay doesn't create nearly enough volume to support that kind of manufacturing, which means most Dorman parts are provided to independent auto shops. What repair shops hate most is customer comebacks because a repair didn't work, so if Dorman consistently produced crap products, nobody would use them.

Just my $0.02 worth.
 

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Discussion Starter #8
Problem update: A couple of times, got a p0123 code (throttle position sensor circuit). But after I cleared, then restarted a couple of times, it went away.

Now, with all codes cleared: engine starts, idles fine, sounds good. But above approx 2,000 RPM, it stumbles, turns on check engine light, and I get a p0351 code -- circuit for #1 ignition coil. Checked coil, continuity good, same resistance as two coils checked on other cylinders. Swapped one of those coils with the #1 coil, just in case, but got same behavior and same code.

I still have the feeling this is a wiring harness problem, not an individual component problem. I handled the wires a lot when I was rooting around under the intake plenum a while back changing a water pump and timing chain. Some parts of the harness show wear (frayed wrap, twisted wires at connectors, etc.) Also, one set of wires wraps tightly around the rear corner of the engine on the driver's side, and it's a tight fit where I've noticed abrasion in the past.

I have a code reader, but it's very basic. How much better would a more sophisticated scanner work? (I have a lot of cars, and do my own work, so I could justify the investment, if necessary.)

Also, I've read that with some of the p035- series codes, sometimes the wiring to the CRANK position sensor (or a bad sensor) can make a difference. Comments? I'm willing to replace the sensor without confirming, just because sometimes it's much cheaper to buy a new part, likely to last the life of the vehicle, than to spend a long time diagnosing.

The car (2002 w/ 2.7 engine) only has about 105k miles, but IMO sensor and wiring failures are more likely to relate to age, not mileage.

In my most recent round of tests, there were zero cam position sensor codes. I'd replaced that sensor under the (possibly mistaken) assumption that it was bad because of the engine stumbe above 2,000 RPM, which WAS a sensor problem the last time. But now I'm thinking maybe the cam sensor had nothing to do w/ my current problems.
 

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I can give you 2 examples of bad products from Dorman. (1) The replacement coolant reservoirs that Dorman makes for our cars are made from inferior plastic matetial. There have been many people on this forum that tried to save money and used the Dorman to replace the reservoir, and less than a year later, the new reservoir ruptured from the heat and pressure. (2) The Dorman bushings in the engine cradle bushing and bolt replacement kits are a horrible fit. The bolts are a good fit. The general advice in this forum has been to buy the kit for the bolts, throw the bushings away, and get the bushings from a dealer or get some polyurethane ones custom made for our cars.

Not everything that Dorman sells is crap. The bolts that come in the bushing kit are OK, and apparently the replacement crankshaft damper pulley they sell for the 3.2/3.5 engines are decent.
 

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Symptom List:
P0351-IGNITION COIL #1 CIRCUIT
P0352-IGNITION COIL #2 CIRCUIT
P0353-IGNITION COIL #3 CIRCUIT
P0354-IGNITION COIL #4 CIRCUIT
P0355-IGNITION COIL #5 CIRCUIT
P0356-IGNITION COIL #6 CIRCUIT
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0351-IGNITION COIL #1 CIRCUIT.

When Monitored and Set Condition:
P0351-IGNITION COIL #1 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One Trip Fault.
P0352-IGNITION COIL #2 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One trip Fault.
P0353-IGNITION COIL #3 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One Trip Fault.
P0354-IGNITION COIL #4 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One Trip Fault.
156
DRIVEABILITY - NGC
P0355-IGNITION COIL #5 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One Trip Fault.
P0356-IGNITION COIL #6 CIRCUIT
When Monitored: With battery voltage greater than 11 volts. Engine running. Engine
RPM less than 8160. No coil in dwell during test.
Set Condition: Peak current is not achieved with battery based dwell plus 1.5 msec of
diagnostic offset. It takes less than 3 seconds during cranking or up to 6 seconds while
running to set. One Trip Fault.

POSSIBLE CAUSES
GOOD TRIP COUNTER = 0
ASD RELAY OUTPUT CIRCUIT OPEN
CAPACITOR(S) SHORTED TO GROUND
ASD OUTPUT CIRCUIT SHORTED TO GROUND
COIL ON PLUG
COIL CONTROL CIRCUIT SHORTED TO GROUND
COIL CONTROL CIRCUIT OPEN
PCM
 

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Problem update: A couple of times, got a p0123 code (throttle position sensor circuit). But after I cleared, then restarted a couple of times, it went away.

Now, with all codes cleared: engine starts, idles fine, sounds good. But above approx 2,000 RPM, it stumbles, turns on check engine light, and I get a p0351 code -- circuit for #1 ignition coil. Checked coil, continuity good, same resistance as two coils checked on other cylinders. Swapped one of those coils with the #1 coil, just in case, but got same behavior and same code.

I still have the feeling this is a wiring harness problem, not an individual component problem. I handled the wires a lot when I was rooting around under the intake plenum a while back changing a water pump and timing chain. Some parts of the harness show wear (frayed wrap, twisted wires at connectors, etc.) Also, one set of wires wraps tightly around the rear corner of the engine on the driver's side, and it's a tight fit where I've noticed abrasion in the past.

I have a code reader, but it's very basic. How much better would a more sophisticated scanner work? (I have a lot of cars, and do my own work, so I could justify the investment, if necessary.)

Also, I've read that with some of the p035- series codes, sometimes the wiring to the CRANK position sensor (or a bad sensor) can make a difference. Comments? I'm willing to replace the sensor without confirming, just because sometimes it's much cheaper to buy a new part, likely to last the life of the vehicle, than to spend a long time diagnosing.

The car (2002 w/ 2.7 engine) only has about 105k miles, but IMO sensor and wiring failures are more likely to relate to age, not mileage.

In my most recent round of tests, there were zero cam position sensor codes. I'd replaced that sensor under the (possibly mistaken) assumption that it was bad because of the engine stumbe above 2,000 RPM, which WAS a sensor problem the last time. But now I'm thinking maybe the cam sensor had nothing to do w/ my current problems.

Do you want to pay close to OEM prices for aftermarket products of dubious quality?

Our advice wasn't for Dorman products in general...it was for a specific set of parts related to the LH cars.

Of course if you want to experiment and try these questionable parts then by all means do so !

Think about this...a Dorman Exhaust manifold will not be the same as a Crank Position Sensor. And Mopar will give you 12/12k miles warranty. What's Doormat giving you?
 

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Woober Goobers!
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Please feel free to try all of these Dorman products.

It seems you want others to do this before you while not wanting to spend any money.

You can quote the manufacturers website all you want. It's been proven several of their products are "Crap" for our LH cars. Have at it and give us a review ?
 

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OH and for Cam/Crank sensors it's the consensus that OEM is the only way to go. This includes Jeep, Durango and 300 forums>
 

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Discussion Starter #14
Well, returning to my original problem (engine sets a P0351 code at 2,000 rpm, stumbles, will barely rev any higher), I'm still stuck.

This behavior is identical to a problem, that in the past, was fixed by replacing the camshaft position sensor. But a replacement part produces exactly the same problem.

The OBD code, however, isn't for the sensor. P0351 says the problem is in the ignition circuit for the #1 cylinder. But swapping that coil with another one on the engine makes no difference. Same code, so it's not the coil.

Since the cam and crank sensors share the same wiring harness, and there have been suggestions that a problem in one circuit could affect the other, I made some electrical tests on both connectors (each disconnected from the actual sensor).

With ignition off: ground circuits good, low resistance.
With ignition on:
--Supply circuits from PCM (power control module, aka engine computer): good (approx 5 volts)
--"Signal" circuits from sensor back to PCM: same reading as supply circuit. (I don't fully understand this, shouldn't it read zero volts?)

Since the results are identical, however, that suggests it's not a short circuit or bad ground.

I find it difficult to believe that a problem in a coil circuit occurs ONLY when engine speed hits 2,000 rpm (every time). If a coil is firing OK below that speed, it's probably firing OK above it. Clearly, the computer thinks something wrong is happening at that engine speed -- but what? My gut feeling is (still) that it's related to the wiring, especially since the factory manual points out REPEATEDLY that many PCM problems and/or trouble codes are the result of wiring issues, not the sensors.

Attached are a couple of PDFs describing how the PCM works, and how to diagnose P0351. All further help appreciated.
 

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Discussion Starter #15
One thing I just noticed: in the factory manual, it says the ignition circuit is monitored only with engine speed less than 2,016 RPM. But if I don't exceed that speed, engine runs perfectly and there's no trouble code. So, again, what is happening at 2,016 rpm?
 

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The ignition timing runs off the crankshaft position sensor up to about 2000 rpm, then times off the camshaft position sensor above 2000 rpm. So - if camshaft position sensor or its wiring are bad, the engine runs fine up to about 2000, but won't run any higher.

The voltage you see on the signal wires is correct. Those wires are "active high", which means that the PCM pulls that wire to voltage (with a pullup resistor) with no sensor connected. With sensor connected, the sensor has two states: Off (high impedance, so the wire remains pulled up to the voltage) and On (conducting, pulling the wire to ground).

Are you installing the two cam position sensors with a paper (or tape) spacer pushed against the tone wheel each time? If not, they may be hitting the tone wheel and being damaged. Do the tips of those sensors look damaged?
 

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Discussion Starter #17
I don't know anything about paper or tape spacers. How to use? I'll take another look at the sensor tip, but didn't notice anything untoward. Is this procedure only for cam sensor?
And if the reason is to maintain xx clearance between the sensor tip and wheel, wouldn't tightening the hold-down bolt push the two surfaces together anyway? If so, that suggests need for a spacer washer between the engine block and the mounting hole surface to maintain distancing. True?
Thanks for your explanation of the transition from crank to cam sensor -- this makes perfect sense.
I am cautiously assuming that the crank sensor is OK, so that helps narrow my focus to the wiring for the cam sensor, and/or the clearance issue. As usual, many thanks for your expertise!
 

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Discussion Starter #18
To answer my own question: According to the factory manual, the use of a paper spacer when installing the cam sensor is required only with the 3.5 engine. Since mine is the smaller 2.7, the quest for a solution continues.
 

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Sorry - I missed seeing your previous post.

And - you are right - cam sensor spacer not on the 2.7. I missed noticing yours is a 2.7 even though you stated that at least twice - or I just forgot that the 2.7 doesn't have the spacer.

But the way that works on 3.2/3.5 is the sensor body fits inside the mounting flange - it's a slightly tight fit. The sensor is shipped with it extended past its final installed position. When you install it, the spacer is forced against the tone wheel, pushing the sensor into the flange to the correct position. When the engine is started, the spacer is knocked off.
 

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Discussion Starter #20
Ah,. that makes sense.
Returning to my problem, I dug into the wiring today, removing tape and accordian wrap around the wiring bundle from the cam sensor to the power control module (engine computer). Looked for damaged wires, possible shorts, etc., but didn't see anything obvious.
Then I disconnected the cam sensor, and also the wiring bundle's connection to the computer (a BIG connector carrying many circuits). Then, at the sensor connector, I tested for any continuity between the ground wire and the two "hot" wires -- one the feed to the sensor, the other the return signal to the computer.
One of those hot circuits (can't remember which, off the top of my head, but probably the feed to the sensor) showed continuity w/ the ground circuit. I think that's wrong -- that neither circuit should show any continuity.
If I'm correct, there's a current leak somewhere in that harness, and I believe the feed for the cam sensor also feeds at least one other sensor. The problem is that the harness includes many other circuits and connectors -- it's a big bundle of wiring that runs along the passenger side of the engine, has connectors to many other circuits, then eventually dives under the intake plenum at the back of the engine.
So, I'll need to remove the plenum (one of my least favorite jobs), disconnect EVERYTHING from that wiring harness, and start testing continuity until I find another hot circuit that's also leaking to ground. Fixing that, in theory, should fix my problem.
Does this sound like I'm on the right track?
Just for fun, I looked up what a replacement Mopar engine wiring harness would cost -- more than $500. Unfortunately, no Dorman alternative ... :)
 
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