liberty wont start

[tkarner03]

a couple days ago my liberty died on me while on the highway and since then it wont start. it cranks and is getting fuel but still isnt firing. it was throwing a code for the camshafter position sensor so i went and swapped that out and now the check engine light is off but still wont start. just trying to look at all options before throwing even more money into it. any input is welcome and appreciated

 

[Snail Farmer]

Try the crankshaft postition sensor. Sometimes it'll throw the code for one or the other, but it's not definitive. The crank position and cam position sensors both send signals to the pcm to control timing. And it's cheap, so if it doesn't work, you're only out a few bucks.

 

[Paul M]

Try the crankshaft postition sensor. Sometimes it'll throw the code for one or the other, but it's not definitive. The crank position and cam position sensors both send signals to the pcm to control timing. And it's cheap, so if it doesn't work, you're only out a few bucks.

Where is the CPS on the Liberty? I'd like to have one in the field kit just in case it decides to fail somewhere a long way from home and a sharp rap on it doesn't get it temporarily working again. Our '88 Commanche ranch truck has it just behind the firewall at the top of the crankcase...a real pain to replace for such an important sensor...but the truck won't start if this thing fails.:disgust:

 

[Snail Farmer]

You're in luck. I actually have a picture I took for someone else on here. On the 3.7 it's on the right side of the block in the rear. Have to crawl under it to get to it.

 

[Paul M]

You're in luck. I actually have a picture I took for someone else on here. On the 3.7 it's on the right side of the block in the rear. Have to crawl under it to get to it.

Excellent! Thanks. At least this one is accessible and changeable in the field, especially since it can fail leaving you stranded. The one on our old Commanche is so hidden it boggles the mind. Because these sensors are usually a hall effect type, if they get hot (warped) or out of position (range) they lose signal, confusing the computer, which decides to not start the vehicle. Sometimes a short rap can get them working again. Going to order myself a spare.

 

[tkarner03]

well i changed the crankshaft and cam position sensor and still no check engine light but still wont fire. ahhh this *****!

 

[Snail Farmer]

Ok, next thing I would check. Under the hood in the fuse box, swap the ASD relay with the relay from the fan to test it. If it fires there's your problem, go buy a new relay. That one's free to check