Crankshaft position sensor

[6speedsd]

So, we've had issues with a truck not starting when cold. 2003 with a 6.0 Had a diesel mechanic tell us with the issues we had, it sounded like the crankshaft position sensor was bad. He said when you turn the truck over, the tach should be moving. If it doesn't move, then the CPS is bad. Is this true? My 04 runs perfect, cranks perfect, no issues at all, but my tach doesn't move when I turn it over. the 03 turned out to be a bad battery. Replaced that and it starts fine now. But I'm just wondering how much truth there is to what that guy told us. Anyone with their own opinion?

 

[Mdub707]

How old are the batteries? I'd start with having them load tested. Testing the FICM after that would be a good thing to do too. Batteries and FICM's seem to account for about 90% of cold hard start issues with 6.0's.

 

[dzldoctor]

very rare a CPS is bad on a 6.0

 

[6speedsd]

Battery was bad. That fixed the hard start issue. Tested the FICM afterwards and voltage was still 48 all the way through.

My question wasn't what the no start problem was. I was just curious about the CPS, and how much truth there was to what that mechanic told us.

 

[bismic]

A CPS is a Camshaft sensor (not crankshaft sensor) and in a 6.0L the camshaft sensor is called a CMP and the cranksensor is a CKP.

From what I am told, the RPM gauge signal comes from the CMP, but I know of one example where a forum post specifically stated that a loss of RPM signal at the panel gauge was a result of a bad CKP (but that same poster had an rpm signal showing from his electronic scan tool that was reading from the OBDII port).

 

[6speedsd]

Ok the sensor I'm talking about is the one down on the passengers side right behind the ac compressor. All the local parts stores list a crankshaft position sensor for a 6.0, so I assume they are all wrong?

Once the truck is running the tach does work on the cluster. This guy just said that it should also move or register when the truck was being turned over.

 

[DEEZUZ]

I can honestly say I never replaced a CKP or CMP, unless some n00b worked on it before and saw the CKP code from the engine turning over too much and not firing. I've have to go back in with a grinder and that out the rust that they didnt bother to brush off before sticking the new sensor in, therefore giving a false reading

 

[6speedsd]

Well my thoughts were if that sensor was bad, or going bad, it should have thrown a code. But he had no codes. Oh well, truck is cranking fine now, so all is well. Now if we could just figure out that front end shimmy deal he has!