Engine/Transmission (1998.5 - 2002) NO camshaft sensor signal ?

[JWine]

please help... my truck quit running on the interstate last week. Self diagnosed injection pump because truck would only run on ether. changed pump, still no start,take to mechanic switched camshft sensor because no trigger signal. no start. switched ecm, starts runs good no codes, driven 5 or 6 miles numerous starts, alls good but no cam signal on snap-on scanner, can unplug cam sensor and still starts and runs. Any thoughts as to this burning up the old ecm. thanks

 

[JLandry]

Could it be a wiring harness problem? Was that checked out?



John L.

 

[JWine]

Looking for a short, but wanted to know if running the truck the way it is could hurt the new/used ecm thats in there now, also tried another good ecm on there and it has the results , runs good but no cam signal on the scanner, am i definetly soposed to be able to read cam signal on the scanner? Truck has been down for week an half, bad for business Thanks for the help

 

[JLandry]

... wanted to know if running the truck the way it is could hurt the new/used ecm thats in there now...

I don't see how it could. The only way you could damage the ECM would be to feed it too much voltage on a sensor wire. For example, if one of the 5 volt sensor wires got inadvertently shorted to 12 volts.

... am i definetly soposed to be able to read cam signal on the scanner?

If the scanner is normally capable of obtaining the cam sensor signal from the ECM, I would sure think so. But not all scanners are capable of reading the cam signal.



Just an FYI, the Bosch VP44 injection pump can operate without a cam timing signal from the ECM because it has the ability to calculate the cam position internally.



I don't think you mentioned it, but are you getting a P0341 diagnostic trouble code from the ECM (Camshaft Position Sensor Signal Missing)? Besides possible problems with the wiring harness, cam sensor, or ECM, loss of the signal can also come from a damaged tone wheel.



Without a cam signal, the tachometer in your instrument panel shouldn't be working. Is this the case?



Regards,



John L.

 

[JWine]

the truck hasn't had a cam trouble code now or before, the tach works fine, shows same rpm as the scanner, the scanner isnt mine but its a newer snap-on. getting 5 volts and good ground to sensor have to trace signal wire next. Thanks for the reply

 

[JLandry]

the truck hasn't had a cam trouble code now or before, the tach works fine, shows same rpm as the scanner, the scanner isnt mine but its a newer snap-on. getting 5 volts and good ground to sensor have to trace signal wire next.

If your tach is working fine and you have no DTC's, then there's absolutely nothing wrong with your cam sensor or the ECM. That particular scanner from Snap-on simply must not be able to read the cam sensor signal over the communication bus. If you really want a second opinion, take the truck to a Dodge dealer and they can use a Chrysler DRBIII scan tool to verify the signal, but I don't think you need to waste the time and money doing so.



Sounds like swapping out the ECM inadvertently fixed whatever problem you were having, so if it's otherwise operating fine, just drive it!



Best regards,



John L.