You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
cam sensor cap
- Thread starter yelowta
- Start date
Is using the oscilloscope something a mechanic would normally do? This guy came highly recomended, he has put together 2 of his own grand nationals. I have brought this car pretty far mostly on my own, from a car sitting for 15 years in a garage i got the car in awesome condition 60000 miles but but with 2 motors in pieces in boxes. I finally had to bring it somewhere because I didn't have the resources nessecary to finish. 1 1/2 years and its so close.
- Joined
- Feb 18, 2006
Is using the oscilloscope something a mechanic would normally do? This guy came highly recomended, he has put together 2 of his own grand nationals. I have brought this car pretty far mostly on my own, from a car sitting for 15 years in a garage i got the car in awesome condition 60000 miles but but with 2 motors in pieces in boxes. I finally had to bring it somewhere because I didn't have the resources nessecary to finish. 1 1/2 years and its so close.
I don't know where you buy just the cap but you can get the complete sensor from a couple of the vendors. Gbody or HighwayStars.
Did your mechanic try another cam sensor from a working car?
What other things go wrong with these cars that would appear to be the cam sensor? I'm hoping this guy isn't trying to pull a fast one he said he can get a delco i've heard getting one is very rare and exspensive. Has anyone used an Echlin one are they good? I can get one for 249 and change which is more than half of the delco one. I'm getting frustrated with this car it's so close to being done.
You should ....
send that cap back to John, he's an upright guy. He will check it out and let you know if it is faulty or not. Don't take the mech's word for it being "no good." Besides, if it does prove bad, you will have preserved the mech's reputation for being both honorable and knowledgeable, putting your mind at ease.
send that cap back to John, he's an upright guy. He will check it out and let you know if it is faulty or not. Don't take the mech's word for it being "no good." Besides, if it does prove bad, you will have preserved the mech's reputation for being both honorable and knowledgeable, putting your mind at ease.
OK, so the cam sensor cap reads the ring on the top of the post. It has a window in it and when it is set correctly the ECM knows exactly where the motor is at in its rotation.
The cam sensor signal is read by the CCCI. The CCCI actually sends the signal to the ECM. So if you are getting a reading that you have a bad cam sensor, then it can be a few things.
1. It's actually the cap.
2. The ring has come loose and is not really spinning with the motor.
3. The wiring to the CCCI from the cap is bad (wiring or connection).
4. The CCCI is bad.
5. The wiring from the CCCI to the ECM is bad (wiring or connection).
6. The ECM is bad.
I do know many GM techs who use scopes to find electrical problems. Did this guy use one? You're going to have to find that out.
The cam sensor signal is read by the CCCI. The CCCI actually sends the signal to the ECM. So if you are getting a reading that you have a bad cam sensor, then it can be a few things.
1. It's actually the cap.
2. The ring has come loose and is not really spinning with the motor.
3. The wiring to the CCCI from the cap is bad (wiring or connection).
4. The CCCI is bad.
5. The wiring from the CCCI to the ECM is bad (wiring or connection).
6. The ECM is bad.
I do know many GM techs who use scopes to find electrical problems. Did this guy use one? You're going to have to find that out.
Thanks T-top, i'm going over there tomorrow I will print this out and show him while trying not to insult his intelligence. The guy told me how he determined what was wrong, he said he probed the grey wire in the plug and grounded it and there was injector pulse and spark does that sound right? I can turn wrenches and put almost anything together but diagnosing electrical probs. I need to learn more. This site is great for help and parts that is for sure.
The grey-red wire from the cap to the CCCI only supplies 12v to the cap.
The light blue wire from the cap sends the signal to the CCCI. From there it goes into a buffer internal to the CCCI and the CCCI sends the signal to the ECM on A11, a yellow wire.
If I can find the video I took of the scope when I was testing my cap, I will post it.
The light blue wire from the cap sends the signal to the CCCI. From there it goes into a buffer internal to the CCCI and the CCCI sends the signal to the ECM on A11, a yellow wire.
If I can find the video I took of the scope when I was testing my cap, I will post it.
OK I found it.
So, every block on the Y axis is 5 volts. What you are seeing is the ~7.5v signal on most of the screen. But, as the gap (window) in the ring spins through the cam sensor cap, the voltage drops to ~0v. You will see what is basically a square wave signal. My scope isn't the greatest so you don't see the vertical line being drawn.
When you set the cam sensor, you rotate the motor to 25* After Top Dead Center on cylinder #1's compression stroke. Then, you set the sensor by rotating it counter clockwise until the sensor "sees" the beginning of the window. Then you tighten it down and the ECM knows where the motor is at in rotation.
The cam sensor is needed to start the car but it can run without which you can prove by unplugging after the car is started. What the ECM DOES use the cam sensor for after the start is to sequentially fire the injectors. If the cam sensor fails while the motor is running or you unplug it, the ECM will fail back to batch fire mode so you can limp to a garage and get it fixed.
I hope all of that makes sense.
http://buickman.r00td0wn.net/Cam-Sensor-Signal.wmv
So, every block on the Y axis is 5 volts. What you are seeing is the ~7.5v signal on most of the screen. But, as the gap (window) in the ring spins through the cam sensor cap, the voltage drops to ~0v. You will see what is basically a square wave signal. My scope isn't the greatest so you don't see the vertical line being drawn.
When you set the cam sensor, you rotate the motor to 25* After Top Dead Center on cylinder #1's compression stroke. Then, you set the sensor by rotating it counter clockwise until the sensor "sees" the beginning of the window. Then you tighten it down and the ECM knows where the motor is at in rotation.
The cam sensor is needed to start the car but it can run without which you can prove by unplugging after the car is started. What the ECM DOES use the cam sensor for after the start is to sequentially fire the injectors. If the cam sensor fails while the motor is running or you unplug it, the ECM will fail back to batch fire mode so you can limp to a garage and get it fixed.
I hope all of that makes sense.
http://buickman.r00td0wn.net/Cam-Sensor-Signal.wmv
You know the funny part is I don't know crap about carbs.
That is funny and I'm in the same boat.
Similar threads
- Replies
- 25
- Views
- 2K
