need help with cam sensor replacement

[Melinda T]

I have a cam sensor that I need to replace. Since there are 6 of them, I'm not sure how to test this out to see which one is bad. Can anyone give me some advice?

[CLEVEN]

From what i know 3400/3100's only have one behind the power steering pump

[zzyzzx]

From what i know 3400/3100's only have one behind the power steering pump

Exactly what I saw when I removed the LIM. It's won't be easy to get to either.

[phillipandtabby]

yep just one.

[Melinda T]

ok, I must've gotten some bad info! I was told there were six, lol. Well, this is gonna suck, then. What's a LIM?

[TdotAlero]

What's a LIM?
Lower Intake Manifold I believe

[lonnie]

Welcome to the site. Hampton VA I assume?

[clutch1]

Lol!

Why do you think it's bad?? Car won't start??

It is indeed right under the power steering pump.. pretty easy to remove too. Take off the belt then the pump and you can get to it.

Anyways.. to test it.. Go to the 3wire plug by the alternator that goes down to it. One wire should have 5v on it. One wire should have UNDER .1v on it. And one wire is your signal. You'll need an oscilloscope to look at it's wave form.. get that pulled up and you should see one 5v "box" on the waveform for every two revolutions of the engine (and everyone revolution of the cam).

And that is how you test the cam sensor.

[lonnie]

Lol!

Why do you think it's bad?? Car won't start??

It is indeed right under the power steering pump.. pretty easy to remove too. Take off the belt then the pump and you can get to it.

Anyways.. to test it.. Go to the 3wire plug by the alternator that goes down to it. One wire should have 5v on it. One wire should have UNDER .1v on it. And one wire is your signal. You'll need an oscilloscope to look at it's wave form.. get that pulled up and you should see one 5v "box" on the waveform for every two revolutions of the engine (and everyone revolution of the cam).

And that is how you test the cam sensor.
Yep......I can see her doing this!


LOL!

[Melinda T]

It starts just fine, but when i come to a stop, it tries to die. My service engine light was on, so I took it to Auto Zone to see what code it was throwing. Cam sensor. I'm from IL, not VA.

[Melinda T]

What do you mean by an oscilloscope...A multi-meter?

[Monza]

The scope has a display that shows voltage change over time. So at 800 rpm you'd see voltage rise to 5V, hold, and then drop every 1/400th of a minute (.15 seconds? Excuse my poor math). Anyway the wave form should be fairly square.

[clutch1]

Yep, it's basically a multimeter that also graphs a line. Very very handy.

As for dying at stop signs.. Check for vacuum leaks!! If you can, pump smoke into the manifold. Or if you have a scanner, look up live fuel trims numbers. At idle, if you have very high long term of short term fuel trims (LTFT / STFT), then they drop if you raise rpms to 2000, it is a vacuum leak.

What specific code was it throwing for the cam sensor??? Do you have a number? That could help with diagnosis more

[Melinda T]

I took the car back for the code. P0341 Definition: Cam sensor condition. Explanation: The camshaft position sensor signal is monitored for errors. Probable cause: 1. Cam sensor defective 2. Check connector and wiring to sensor. 3. Engine mechanical condition-timing belt/chain out of time (yikes...that ain't good!) 4. Cylinder misfire- check ignition system for faults-plugs, wires, coils. Hope this helps!!!

[zzyzzx]

It's unclear to me as to how the car can even run in the first place with a defective cam sensor. I'd be researching that code to see what it really means, and I'd check the wiring for dirty contacts, then vacuum leaks, etc.

[clutch1]

Cam sensor just tells the car when cyl #1 is on TDC compression so it know what sequence to start firing the plugs. Some cars only use them for start up. Some cars, if the cam sensor is defective, just guess and take afew tries to start until they guess right.

However, from the description of it, "Cam sensor Circuit Range/Performance" it sounds like it's almost assuredly the cam sensor. Wiring *usually* is ok, but run those few checks.. I'd bet money on the sensor being out though.

Can you see down to it with a flashlight or something? A lot of times they get covered in powersteering fluid, that'll kill them dead.

[JDutch]

I am working on replacing my cam position sensor in my 1999 3.4L Alero. My check engine light has been on for about a year (shame on me) due to a code related to the cam position sensor. The car is running fine and I just haven't bothered to mess with the problem. Now I have to get my car e-Checked, so I've got to resolve the issue and replacing the sensor is the obvious first step, from what I understand.

I have taken off the serpentine belt and the three bolts out of the power steering unit. I was hoping not to take the hoses off the power steering unit, since that's going to be one more thing that could go wrong once I start cranking on it. Unfortunately, it doesn't seem like the power steering unit will come out, as it is catching on something that I can't see.

Is there anything else I need to also remove to get the power steering unit out? Must I disconnect the power steering hoses?

Thanks for any suggestions.

[JDutch]

In answer to my own question, to remove the power steering pump, you must disconnect the two power steering lines, as well as the electrical connection to the pump. Having a golf tee handy to plug the one hose is helpful to avoid a mess.

The cam position sensor is readily available once the power steering unit is out.

Replacing the cam position sensor did not fix my problem, though. The code has not cleared on its own after numerous starts.

I suppose replacing the the spark plug wires is next. I have already replaced the spark plugs to no avail.

[Gr1m]

you actually dont have to disconnect the PS lines, you can just get the bolts through the hole with a swivel and move the pump behind the alternator. are you guys sure its your cam sensors and not crank sensors? the crank sensors are way more common to go bad

[JDutch]

Thanks for the reply.

I couldn't figure out how to get the pump out without disconnecting the hoses. That whole job was fairly miserable for an amature like me.

Turns out the code did actually clear. I had them read at Autozone and I'm actually now getting a P1641 (MIL control circuit fault) and P0440 (EVAP small leak/no flow control). I suspect the second is probably just a gas cap issue. The guy told me the first may mean that my Check Engine light is stuck "on". LOL. He was probably trying to get rid of me :) I'll have to do a little research and see what to do next.

[JDutch]

Turns out the P1641 code is actually related to the A/C. I had noticed my air conditioner had quite working a few months back, but I chalked it up to being old :) The fuse was burned through. I replaced it and now the A/C works. I don't have a code reader, so I don't know if it cleared that code, but I bet it did.

I'm left with the P0440, which is probably a gas cap problem as I've read. I had an Aztec that had a similar problem. I'll buy a new one and see what happens.

[Lucalare]

Turns out the P1641 code is actually related to the A/C. I had noticed my air conditioner had quite working a few months back, but I chalked it up to being old :) The fuse was burned through. I replaced it and now the A/C works. I don't have a code reader, so I don't know if it cleared that code, but I bet it did.

I'm left with the P0440, which is probably a gas cap problem as I've read. I had an Aztec that had a similar problem. I'll buy a new one and see what happens.

Disconnect the negative terminal on the battery for like 20 minutes, that should clear any codes I think.

[Gr1m]

it wont clear the codes properly doing that, they will still be saved in the computer, but it wont throw an SES light until about 5mins after you turn it on, if its something minor (not misfiring)

[JDutch]

Turns out the P1641 code is actually related to the A/C. I had noticed my air conditioner had quite working a few months back, but I chalked it up to being old :) The fuse was burned through. I replaced it and now the A/C works. I don't have a code reader, so I don't know if it cleared that code, but I bet it did.

I'm left with the P0440, which is probably a gas cap problem as I've read. I had an Aztec that had a similar problem. I'll buy a new one and see what happens.

I cleared P0440 code with a code reader and I'm getting it back again after some driving. I have replaced the gas cap, so I'm afraid it may be more serious.