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Blakehenryy

P0336 No Tach, Lack Of Power

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Just picked up the truck from a buddy, it’s a 1999 Dodge Ram 2500 24v Cummins. Sold it to me for a good deal with one problem code p0336 no tach, causing a lack of power. He told me he replaced the sensor with many different brands, and got them ecm tested and the tach worked on bench. The oreillys brand sensor works the best, works for 3 seconds and tach dies. He called a mopar friend of his and he told him to get a cummins brand crank and cam sensor. I got a cummins crankshaft sensor and tach didn’t move. Recorded live data from my code scanner and my OBD2 is able to read my RPMs, but nothing on the dash. I’m stumped

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If you keep replacing the crank sensor and get the same result then it's not the crank sensor.  The ECM was good when tested so new sensor and good ECM then may be bad connector/wiring.   I would start doing some doing some volt/ohm testing on that circuit. 

Read this and do the tests then let use know what you find.

 

 

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I have a spear ecm programmed to my truck and if I use it my tack will randomly drop to 0 on cluster but in quadzilla it still shows rpm. It will set a 1698 code. Switch back to the other ecm and no problems. Not saying it's your ECM but it could be. 

Like IBMobile mentioned start with that thread and check wires.

Another question is have you checked ac noise and done all the ground mods. It will prevent future electronic failures. 

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Sorry for the long time with no update. I was running some test on it and in the process I fried the oem crank sensor, Anyways. I tested the continuity on all 3 wires from the sensor to the ECM and all 3 passed. Turns out I was wrong on what pin was what. Signal is pin #16, ground is #4 and constant 5v is #3. I tapped into the sensor side signal wire while running and I get a bunch of voltage jumping, so I guess that passes. So what’s next to test? Also, I put the old oreillys one back and the Rpms started to working for 5 seconds then tach die again. but I noticed with the 5 seconds of it running it sounds like it runs bad, but once the tach dies it’ smooths out.

On 1/12/2019 at 12:24 PM, Mopar1973Man said:

Remember excessive AC noise will pollute and hall effect sensors like crank, cam, ABS, etc. Creating false speed signals.

 

This question is actually for you. I posted the same topic in cummins forum and a guy direct me to your website, where you did a break down on how to test the p0336. And now I’m stuck. I’m on #8 where it says “ Ensure CKP sensor connector and ECM connector are still disconnected. Using ohmmeter, checkresistance between ground and terminal "C" (Gray wire) on CKP sensor connector. If resistance is 5 ohms or more, replace ECM. Perform TEST VER-5A . If resistance is less than 5 ohms, repair short to ground on Gray wire between CKP sensor and ECM. Perform TEST VER-5A .” I did this and I got OL on the ohmmeter. So I put the meter on continuity, the ) ) ) symbol, and I touched one end to the C terminal and the other on ECM pin#17 and got a tone with 0.07.soooo that’s where I’m stuck do I listen to the OL, and what does that mean? Or since I got 5 ohms or more @ 7 ohms I need an ECM?

 

just for a quick link to what I’m talking about

On 1/12/2019 at 12:43 PM, Me78569 said:

Was the engine ever swapped.

Original motor

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Just a quick update: just out of curiosity I decided to test all the pins in the ECM to see if it had continuity with the signal wire and turns out pin#17,30,49 all have a tone. Pin #17 is the crankshaft position sensor signal wire but #30 and #49 are grounds and when I giggle the harness the tone goes in and out. So I’m starting to thing that signal wire is being grounded inside the harness

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It could definitely happen, this is not the first case. @dripley knows all about how to giggle a wiring harness. I believe there is a ground splice just before ECM, it's on my list to do also.

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