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Code - P0340 no cam signal to PCM-info

11-10-2009, 08:33 PM
Sorry if this isn't the right place for this, but I think it's not vehicle specific,and it might help someone, I only included vehicle info for back ground.
This may help someone out there.
It's 02 Liberty LTD 4x4 3.7L
It came into the shop on the hook, of course when I went out the following Monday it started right up and ran fine.
I pulled code P0340 no com signal to PCM, so I went into data display and everything looked fine. after it warmed up and was still running fine, so I took it out, well after about 7mi. it quit the scan tool showed no cmp (cam position sensor), signal and no cmp - ckp (crank position sensor) sync. While cranking the cmp stayed flat, then started reading, it started and I headed back to the shop, stalled and started lots of times till the battery went dead, so I called my partner and had him get a cmp, and bring the jump box. I changed the cpm on the side of the road, guess what it didn't work, so we towed it back to the shop.
Today I checked & cleaned all engine grounds, quite a few had high resistance, I also checked the wires from the cmp to the PCM. Restarted and let run for 40 min. engine temp 210 Deg. it quit. I noted the ckp was still showing a signal when the engine wasn't turning over. I got a new ckp and tested the resistance of the old one vs. the new one, (no lab scope), it showed the old one had low resistance, so I put the new one in.
I let it run from 45 min. w/no problem, so I road tested for a short trip around the block a couple of times with no problems. I drove it home 15mi. and it's doing fine.
I don't know why the ckp threw a cmp code but it did, so if your having a P0340 code ck the ckp also. Maybe some of you already know this, but it was new to me.
I hope this helps someone:2cents:

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