I have 7.6 volts leaving the ECM to the cam positioner. I give the wire 12 volts and the truck runs fine. Could it be a bad ECM?
Sep 13, 2021 at 5:12 AM
Cam Sensor problem
2003 CHEVROLET 2500
RDGLL
- MEMBER
- 1 POST
- FOLLOW
Advertisement
Hello, I'm Danny.
Yes, the camshaft position sensor receives a 12volt reference signal from the PCM. Here is a tutorial on how to test electrical wiring:
https://www.2carpros.com/articles/how-to-check-wiring
I've attached a picture flow chart below with camshaft position sensor circuit description for your truck. Let us know if you have any further questions on this issue. Hope this helps and thanks for using 2CarPros.
Yes, the camshaft position sensor receives a 12volt reference signal from the PCM. Here is a tutorial on how to test electrical wiring:
https://www.2carpros.com/articles/how-to-check-wiring
I've attached a picture flow chart below with camshaft position sensor circuit description for your truck. Let us know if you have any further questions on this issue. Hope this helps and thanks for using 2CarPros.
Images (Click to enlarge)
Sep 14, 2021 at 6:00 AM
I just want to confirm what you are doing so that we can provide the proper response.
You are going to the red wire from the PCM and checking voltage and you only have 7.6 volts? Then you are applying 12 volts and the vehicle runs well?
https://www.2carpros.com/articles/how-to-check-wiring
If this is the case, then you are correct that the ECM is to be providing a 12 volt ignition feed so that the sensor operates properly.
Basically it needs 12 volts to power the sensor and then it will send the proper camshaft position to the ECM so that it knows where the cam is at all times.
If this is what is happening then you do not need to replace the ECM for this issue. What I would do is go to the cam sensor and cut the red wire about 5 inches back from the sensor to give yourself a good amount of wire slack and then run your own 12 volt ignition feed. All you need to do is use a wire that is hot when the key is on. Do not use a wire that is only hot (powered on) in start because you need a constant 12 volts going to the sensor so that it will tell the ECM the position all the time.
Or you can replace the ECM.
The reason this will work is the ECM is only sending 12 volts on this wire. It is not asking for any feedback on this circuit because the feedback is provided through the signal and low reference wires.
I would suggest cutting and splicing in the new wire by soldering it in. Here is a video that shows how to do this. Clearly this is on a headlight socket but the way to solder the wires is the same.
https://www.youtube.com/watch?v=PxA5wczsCVo
Please let us know what questions you have on this.
You are going to the red wire from the PCM and checking voltage and you only have 7.6 volts? Then you are applying 12 volts and the vehicle runs well?
https://www.2carpros.com/articles/how-to-check-wiring
If this is the case, then you are correct that the ECM is to be providing a 12 volt ignition feed so that the sensor operates properly.
Basically it needs 12 volts to power the sensor and then it will send the proper camshaft position to the ECM so that it knows where the cam is at all times.
If this is what is happening then you do not need to replace the ECM for this issue. What I would do is go to the cam sensor and cut the red wire about 5 inches back from the sensor to give yourself a good amount of wire slack and then run your own 12 volt ignition feed. All you need to do is use a wire that is hot when the key is on. Do not use a wire that is only hot (powered on) in start because you need a constant 12 volts going to the sensor so that it will tell the ECM the position all the time.
Or you can replace the ECM.
The reason this will work is the ECM is only sending 12 volts on this wire. It is not asking for any feedback on this circuit because the feedback is provided through the signal and low reference wires.
I would suggest cutting and splicing in the new wire by soldering it in. Here is a video that shows how to do this. Clearly this is on a headlight socket but the way to solder the wires is the same.
https://www.youtube.com/watch?v=PxA5wczsCVo
Please let us know what questions you have on this.
Images (Click to enlarge)
Sep 14, 2021 at 6:11 AM
Advertisement