Hi all,

My 2000 ram 2500 cranked, but would not start. I managed to get it started and it got me home, but the tachometer said 0 for the whole ride.

I scanned it and got p0336 which is a crankshaft position sensor fault. I put a new one in (from rock auto), cleared the code, and when I went to start it, same problem- The starter cranks, but no start. The RPM's stayed at zero when it was cranking.

 

I haven't had great luck with rock auto, so i bought a CKP sensor from advance auto with a lifetime warranty. Put it in, tried to start it and the same exact problem! it cranks but does not start. At this point, i figured it's an electrical issue, so I ran a whole series of voltage and resistance tests. Appreciate the detailed code information!  Each of the 3 parts of the sensor produced voltage or completed a circuit.

 

When i connected A to C (sensor to ecm signal wire), the lift pump turned on. The middle wire B on the connector (on a hall effect sensor) had a lot of resistance from the CKP sensor connector to ECM connector, so I replaced it, and again, the same issue! It cranks but doesn't start.

 

I just got the batteries a couple weeks ago- I've tested them and know they're good. I am stuck and can't figure out what else the issue could be.

I am wondering if:
-for some crazy reason, i got 2 bad brand new sensors?

 

-maybe one of the female connectors doesn't meet the male pins? they sell a part at autozone i can buy to replace the CKP sensor connector

 

-let's say it's not an electrical issue, maybe an issue with the lift pump not sucking enough fuel? when the sensor is disconnected, i can turn the lift pump on manually by connecting A and C from the hall effect sensor. But, when the sensor is in there, i hear the lift pump turn on intermittently, like there is a reset period. but it's not loud like my 3rd gen. in my 3rd gen, any time i turn the key to run, i hear the fuel pump humming loudly from the tank

I've read about this issue and see most people have their issue fixed after replacing a CKP sensor or two. I haven't been so lucky lol.

Please give me your opinion. Could it be an issue in the fuel system? While it ran, the truck drove fine- nothing felt erratic

 

Thanks!

Are your HVAC vents working properly? Looks like rhe main vacuum line fron the vacuum pump to the manifold on the firewall. But if its not connected nothing vacuum operated would be working. I dont have one that runs to the rear of the crank case.

1 hour ago, dripley said:

Are your HVAC vents working properly? Looks like rhe main vacuum line fron the vacuum pump to the manifold on the firewall. But if its not connected nothing vacuum operated would be working. I dont have one that runs to the rear of the crank case.

Mine does, came disconnected one time and I noticed excessive oil coming from the vent tube. Couldn’t figure out why until I saw one day it was disconnected.

must help in the ventilation process? I have an 01 though 

1 hour ago, ColoradoColt said:

Mine does, came disconnected one time and I noticed excessive oil coming from the vent tube. Couldn’t figure out why until I saw one day it was disconnected.

must help in the ventilation process? I have an 01 though 

What does yours attach to at the back of the crank case? Mine came with one line off the pump to the manifold and I added another later for my exhaust brake.

 

If the vacumm line comes loose the vacuum pump pumps air into the crank case instead pullig vacuum on the system and it goes out the vent along with oil.

Thanks again for the responses. I will investigate the vacuum line more next time I look at it.  I just ordered a new (used) harness that was from a wrecked truck that was running. My dad told me I am crazy to put more money into this truck, but I am going to sneak (budget) a part every month or so. I messaged this dude on youtube who had a similar problem and his truck is still sitting after a year, and I don't want to be in that position.

 

I also gotta get the screw out of the ECM. In a month or so, I will bring the ecm to the repair shop. Hopefully if the ecm is good, they at least have a new 50 pin male connector sans the busted hex bolt.

 

I think the new harness will fix at least 50 percent of problem. I think the ECM was fine, but it looks like I gotta fix it now thanks to the screw.

 

I didn't expect these problems when I started the project, but am hoping my work on this will make me a better mechanic. I've learned a lot about electrical testing, scanning and hall effect sensors. When this truck ran, it was fun. It even drove better than my 2005. Hopefully it will run again and be reliable. Maybe I'm just dreaming.