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2003 Ram 1500 - OBD2 Won't Com but was...Crank No Spark
3rd Gen Ram Tech2002-2008 Rams: This section is for TECHNICAL discussions only, that involve the 2002 through 2008 Rams Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
You could be having a tone ring-ECM mismatch. Take a look at this video and see discussion at 17:55;
The Martinbuilt videos are as good as you can get for the 4.7.
I didn't watch the video, but isn't Tone-ring for ABS? I put an PCM from an '02 and it gave a Code 82, "Tone Ring Teeth Factor Out of Range" but that is for ABS.
I didn't watch the video, but isn't Tone-ring for ABS? I put an PCM from an '02 and it gave a Code 82, "Tone Ring Teeth Factor Out of Range" but that is for ABS.
Would not throw an crankshaft error.
The 4.7 uses a 16 tooth tone ring for the crank sensor. Basically, it's a signal generator..... At some point though, they changed to a 32 tooth tone ring, and the two are just not compatible. Not sure what year that change happened though.
The 4.7 uses a 16 tooth tone ring for the crank sensor. Basically, it's a signal generator..... At some point though, they changed to a 32 tooth tone ring, and the two are just not compatible. Not sure what year that change happened though.
Thank you.
When we have the PCM unplugged for hours, when we try to start, I get it to fire a little bit as I'm getting some "POP POP POP" coming out of the manifolds. Then nothing.
I found a wire diagram for the camshaft sensor and crankshaft sensor and check 5V, Ground, and Signal. The cables checked out back to the connector on the PCM and none were shorted together.
So if 16 tooth, that means we get a trigger 22.5 degrees. With the cable plugged in, the key on, I am measuring 5V from Orange to Black, so I know there is power to the sensor. The signal wire is showing 5VDC, however, if I rotate the crank, we should see it go low or 0VDC. By moving ~1 degree, we saw the 5V drop to 0.27V but then quickly jump back up to 5VDC. We could rotate many degrees and never saw the signal stay low.
This tells me either the new crank sensor is bad, or the PCM is bad.
The bluetooth OBD reader has a live mode that shows RPM. To make sure it was working, I had it plot air-temp and throttle position. As I pressed the pedal, I could see TPS change. Air temp was also reading 50 degrees, which is the temp in my garage, so know it was working. RPM always read 0, so PCM is not reading the crank.
Questions:
Do you still suspect a wire issue?
Do you think the cranksensor is bad? We are going to go get another and give it a try.
Do you think the PCM is bad and that is why the cranksensor signal output is stuck on 5V?
Quick update to the above. Cam sensor does toggle 5V/0V/ Checked the crank sensor as sometimes we get RPM to show up on the scanner. I'm now seeing the cranksensor output toggle high-low and also triggers the fuel pump on that transition. Still no spark. With this weird behavior, do you think the PCM is bad?
How many plugs on your PCM? (should be four) Also, the change from 16 to 32 happened in 2003.
Now, it's possible that you might have an early production 03, and it might still be the 16 tooth ring, that would be indicated by only three plugs on the PCM.
How many plugs on your PCM? (should be four) Also, the change from 16 to 32 happened in 2003.
Now, it's possible that you might have an early production 03, and it might still be the 16 tooth ring, that would be indicated by only three plugs on the PCM.
This could be the issue as I did a little more reading on this. This is 4-plug PCM, thus looking for 32-tooth ring and the motor in there now is 16-tooth. I'm going to pull the oil-pan off the old motor that came out and count the teeth tonight.
Reading more, the eighth letter in VIN, M=16, N=32. This is N for 32. 4-plug PCM = 32, 3-plug =16. Maybe the smoking gun here.
If the old motor is 32-tooth and this one is 16-tooth, is there a way to make this motor work and how do we do that (I assume only way is to tear down, pull crank, swap ring and then pull front cover and swap cam gear)?
Thank you for your help so far, I really appreciate it. If any new comments based on the above, let me know?