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Discussion Starter #1
First off I have been cruising the forms for a long time and appreciate all the information this site has to offer.

I can normally just search the forum to help fix whatever problem I have, but this one has stumped me. 2001 6 speed 4wd, all stock for the most part.

Truck runs and drives great. Everytime I start my truck the tach will work for about 3 seconds and then drop to 0 and will never come back to life. I did some research and came to the conclusion it is the CPS. I changed it though (took me about 3 hours and went through a whole can of dip). Anyways the problem is still there... Tach works for about 3 seconds then stops.

I pulled the codes 0460, 1687, 1693. My fuel gauge doesn't work so that explains one and I know the other is just saying I have codes. The 1687 is the No Cluster Bus Message. I guess the CPS I picked up from Oreilleys could be bad, but I doubt it. Is there some other electrical connections I could be checking to help fix the problem? I will clean the PCM/ECM connections tomorrow to see if that helps with the problem.

Any other ideas?
 

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I put a brand new crank sensor from auto zone with warranty, and within a week it failed. On my second and so far so good. But it's not impossible for your replacement cps to be no good right out of the box.
 

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Discussion Starter #3
Yeah I guess it could be possible... Anyway to check it to help determine it is bad before just trying to buy another?
 

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Autozone sells two brands. One is junk the other is not.
 

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Discussion Starter #5
Mine is the cheapest Oreilleys had which is a Spectra one. I think it was less than $40.
 

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Don't know if they have two brands or not or what their quality is of that brand.
 

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Discussion Starter #7
No big deal. I appreciate the input. I will play with some more wires etc. to see if I can get it to work before I pull the trigger on a new CPS. Once I get it resolved I will report what the solution was.
 

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Discussion Starter #8
Well just discovered something new that may be related to my problem. I've only had the truck for about a month and just now noticed that when I turn my headlights on the odometer gauge goes out. As soon as I turn the headlights completely off again the odometer gauge comes back. When the odometer gauge is out its not storing miles. Anyone know where to start looking for this problem?

I've checked my fuses in the cab and none seem to be bad
 

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Discussion Starter #9
Well piss, just figured out it was going away because my dimmer switch was all the way down. I guess it was calculating the miles when it was down and I just thought it wasn't. Still haven't figured out the tach problem yet. I got a no bus message temporarily but after moving the battery cables around and shaking some connectors that went away
 

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Does the tach ever work? My truck had a problem with the crank sensor. As I was driving the tach would drop to 0 and a CEL would come on. Would be a good idea to replace it since it's a cheap part.
 

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Discussion Starter #11
It works for about 3 seconds every time I start it and then after that it won't work until I turn it off again and then restart it. Once again only works for about 3 seconds.

I thought I read on here I don't have a Crank sensor. I honestly think I just have an ecm/pcm ground issue or one of them is trying to take a dump on me
 

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It works for about 3 seconds every time I start it and then after that it won't work until I turn it off again and then restart it. Once again only works for about 3 seconds.

I thought I read on here I don't have a Crank sensor. I honestly think I just have an ecm/pcm ground issue or one of them is trying to take a dump on me
You're right about not having a crank position we sensor, your year came with a cam position sensor, its going to be a PITA to get to but there's another thread on here that has a picture of the exact location
 

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First off I have been cruising the forms for a long time and appreciate all the information this site has to offer.

I can normally just search the forum to help fix whatever problem I have, but this one has stumped me. 2001 6 speed 4wd, all stock for the most part.

Truck runs and drives great. Everytime I start my truck the tach will work for about 3 seconds and then drop to 0 and will never come back to life. I did some research and came to the conclusion it is the CPS. I changed it though (took me about 3 hours and went through a whole can of dip). Anyways the problem is still there... Tach works for about 3 seconds then stops.

I pulled the codes 0460, 1687, 1693. My fuel gauge doesn't work so that explains one and I know the other is just saying I have codes. The 1687 is the No Cluster Bus Message. I guess the CPS I picked up from Oreilleys could be bad, but I doubt it. Is there some other electrical connections I could be checking to help fix the problem? I will clean the PCM/ECM connections tomorrow to see if that helps with the problem.

Any other ideas?
Have you found the problem yet?
I've been having the same issue, I just bought the truck, and the tachometer works for about 3 seconds when it's cold, idles rough, and then the gauge drops to 0 and it idles normal. I've replaced the same cps from o'Reillys and It did nothing. My truck is a manual, so I sorta want that gauge u know.
 

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I posted about testing the cluster in another thread, try that test. Clear any codes 1st and then see if you get codes after the test.
 

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2001 uses the Cam for tach its a really PITA to change out with the VP44 there. I just replaced mine since I did a headgasket pretty easy but with the pump in the spot your going to say a few cuss words. Parts about 32 with shipping '98.5-'02 Dodge Cummins Cam Position Sensor
 

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If it is running fine the sensor is probably fine as the ECM and VP are getting the signal as designed and needed. And becasue you have other gauge issues and a no bus code, you problem is in your cluster not closing its circuit, maybe as simple as a bad ground If you have upper consul you can run a Cluster test, check owners manual for procedure. If the dash has ever been out check the flat ground wire from the door post body to the end of the dashboard on driver side. Maybe the tech it self is bad. Read up on all codes at Morar1973man website.
Always use scan tool for pulling codes, not the key, key is often incomplete.

 

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2001 uses the Cam for tach its a really PITA to change out with the VP44 there. I just replaced mine since I did a headgasket pretty easy but with the pump in the spot your going to say a few cuss words. Parts about 32 with shipping '98.5-'02 Dodge Cummins Cam Position Sensor
Not quite. It gets it's signal over the data buss buss from the PCM, which obviously gets rpm from the cam sensor.
Quote from the manual about the tach:

"OPERATION
The tachometer gives an indication to the vehicle
operator of the engine speed. This gauge is controlled
by the instrument cluster circuit board based upon
the cluster programming and electronic messages
received by the cluster from the Powertrain Control
Module (PCM) over the Chrysler Collision Detection
(CCD) data bus."
 

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If it is in the same place on the timing cover as my 99 I reached it fairly easily with about a foot and half extension, Youare right , no crank sensor but cam sensor works the same way electronically..
 

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I posted about testing the cluster in another thread, try that test. Clear any codes 1st and then see if you get codes after the test.
My obd2 port doesn't work, I've checked the fuse for the cigarette lighter and it's fine so, maybe it's a different fuse or something else. That means I cant check the codes with the obd2. I have a check engine light, so is there a different way I can check codes?
 

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My obd2 port doesn't work, I've checked the fuse for the cigarette lighter and it's fine so, maybe it's a different fuse or something else. That means I cant check the codes with the obd2. I have a check engine light, so is there a different way I can check codes?
Check fuse 12 in the dash box, this one supplies power to the OBDII port.
The cluster test actually spits out it's own code on the cluster after the test finishes. If you get a code from that, post it and I'll tell you what it means.
 
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