turbox2

New ecm new crank sensor new cam sensor but still telling me I need a cam sensor this all started with no start. I have my priming pump on a switch not hooked to pcm is this my problem?

jrs_dodge_diesel

None of the sensors have anything to do with a no start condition.

The only thing needed at startup is 12 Volts and sufficient cranking speed. The VP44 runs alone during startup. After startup the ECM brings the sensors online and works together with the VP44 to control the engine.

Lift pump is controlled by the ECM, not the PCM.

Need to have more information to help with your problem. Any odd engine behavior before your problem started? Fuel pressure? Any codes or check engine lights?

jrs_dodge_diesel

Wait a minute, just read your signature, are the problems your having on your 96 Ram? If so then you very likely have the 12 Valve engine, and not the 24 Valve (electronic) engine that came out mid year in 1998.

If you have the 12 Valve engine, I'll move your post over to the 12 Valve forum.

turbox2

no working on 99 the ecm was bad no start replaced it runs sorta misses at times no tach all other gauges ok gave code for bad crank sensor put in new one now gave code for bad cam sensor put in new one.Still no tach and still giving me code for bad cam sensor the pick up pump is wired to a switch by its self

SIXSLUG

I'd start by checking and cleaning every ground wire you can find....cheap and free

turbox2

All grounds clean still same problem still lookn

KATOOM

Yes, a bad CPS will cause a no start and random hard start condition.

torquefan

Check the tip of your crank sensor for physical damage. There have been cases on the 24 valves where the tone wheel has come loose from the crankshaft and damaged the crank sensor. Could explain why you would have the same trouble with a replacement sensor.

patdaly

^^^^ This, happens more than people think.

jrs_dodge_diesel

In the Caterpillar engine world, we call them magnetic pickups (mag pickup for short). Some of the larger engines get several of these sensors. One difference with them is that the Caterpillar sensors are adjustable, they are threaded and have a lock nut to hold them in place.

I have seen more than one of these with the tips destroyed. Once because a tech didn't adjust it properly and it was too close to the flywheel teeth. That one made a funny noise when they tried to start the engine, a 3508 genset.

Sometimes a metal chip can get stuck to the end and cause interference as well.

turbox2

old crank sensor shows no damage I have replaced the cam sensor p341 code but it still tells me the cam sensor is bad still no tach.when I clear the code and start it it runs 20 sec with tach working ruff engine light comes on loose tach runs smooth crap This is driving me nuts I have worked on all kinds of diesels this one is getting to me guys

AlpineRAM

Some interesting things can be found at
https://www.dieseltruckresource.com/...sensor-259265/

Basically the same reasoning on the 5V supply circuits and the connectors could maybe worth pursuing.
I had a lot of equipment with erratic trouble codes where almost everything had been changed and all was caused by sensor supply getting shorted to ground or shorted to signal.

turbox2

I will check for shorted wires that are messing with 5v signals thanks

jrs_dodge_diesel

Get a multimeter and check for proper voltage at the sensor connections. Should be +5 Volts. Had a case recently where a member here had a sensor that shorted out and disabled several other sensors since they couldn't get power. Once he found and replaced the bad sensor, everything worked correctly again.

SIXSLUG

I was starting to think that^^^ bad wire/connection etc. Chase down with multi meter.