70mph going down the hwy the tach goest to zero and the CEL comes on. The truck is still running fine w/no noticeable changes and all gauges are normal. I took it to check codes yesterday, left it running and the guy comes out turns the engine off, connects to the port and then turns the key to the "on" position, the CEL goes off and it passes the code test. It seems unless running the code is present but one on/off and the CEL clears. Again this morning on the hwy, the tach goes to zero for about a minute and then resumes normal other than the CEL on again. I've searched finding no info on this. I think it may be the crank position sensor but I don't want to just start replacing parts....any help would be appreciated.

 

99 has 2 cam sensor(under vp) and crank sensor (next to starter) cam sensor is more then likely the one doing it . its a bugger to change and I would just change both anyways

 

If it happens again today, I'm going to try to have the codes checked again w/out turning it off. Thanks for the info/specs. Any other thoughts or opinions?

 

My 2000 did the exact same thing. Crank position sensor. Have to remove starter to get it out.

 

Mine has been the CKP also - twice, no codes either time. 1st replacement was oem from Cummins. 2nd replacement was parts store lifetime. At least it will be free (labor only) to change it again.

Leave starter wiring connected & set starter on the frame. You'll need 10mm 12pt wrench (ratcheting is helpful) & perhaps a jack to lever the starter bolts free. Go easy on the CKP. You don't want to break it off in the hole. Rubber O ring (& rust) hold it in once the bolt is out.

 

Ok..sounds like two against one on the issue/problem. From what I've heard the cam sensor is a pita to change. I notice the crank sensor last week when changing out the starter again....it's bolted to the oil pan correct? Thanks for alll the info! Estimated Price?

 

My 2001 only has a cam sensor. Got mine from Hosli Diesel or something like that for 55 bucks shipped. took care of the prob.

 

I remember reading that cam sensor is in later vehicles. 99 (original poster) & 00 (mine) may not have it but I haven't checked the FSM which should be required to be included with every vehicle.

 

Thanks for all the replies. I'm going to get a crank position sensor unless confirmed otherwise.

 

Get the crank sensor. The cam sensor on 98-00 trucks are essentially useless.

 

Exactly. I believe that cam sensor is only there for the cylinder kill function on the scan tool.

 

Thank you!!!!!

 

Follow up
Replaced the CRANK sensor and no problems to date. Thought I could remove it w/out removing the starter but nope.