? No Start ? Intermittant = Bad CPS, Fixed It

DocB · **Posted:** Wed Jul 16, 2014 12:48 am

Hello Fellas, could use a little help here.

Parked the Jeep, and it was running just fine.

Now, it cranks over, but that's about it. Won't light up.

The only code I get is P0725 Engine Speed Input Circuit-Trans Speed Sensor.

There is fuel in the filter, but it's due for a change anyway, so I will do that tomorrow.

My only option at this time is to drag it off to dealership, which I really don't want to do. Preaching to the choir.

I've got alot going on in my life right now, and this is a really bad time for this to happen. Plus, the dealership can't take it in until NEXT Thursday.

Any ideas? Advice greatly appreciated. Thanks.

WWDiesel · **Posted:** Wed Jul 16, 2014 5:16 am

Based on DTC, I would say your crank sensor has went bad or you have a bad connection? Engine OBC will not let engine start if there is no speed input present :banghead:

Would be worth a try to replace speed sensor pickup and check all connections, wiring, etc...
Good luck and let us know what you find! :JEEPIN:

Billwill · **Posted:** Wed Jul 16, 2014 7:53 am

I do not see a P0725 code in my 2006 CRD FSM but it may be an old code and your description would appear to show a problem with the sensors on the transmission so I doubt that would stop it from starting. If possible clear the code and see what comes up next....cam or crankshaft sensor should post a valid code if they are at fault.

First make sure you get any air out of the fuel filter....these air-in-fuel problems usually do not post any codes.

Bear in mind that the USA 2006 CRD has a known problem of the harness being crimped tightly to the chassis behind the fuel filter head mounting bracket which can cause all sorts of electrical problems. You need to remove this bracket and check the wiring in that area!

papaindigo · **Posted:** Wed Jul 16, 2014 9:12 am

I would agree on bleeding the fuel filter head just in case; also if the filter has been on there a long time or you are using high % biodiesel or if you recently filled up you might consider a filter change which I see you already plan to do.

I could be wrong, memory is not perfect, but notwithstanding billwill's comment I don't think a bad crank position sensor will throw a code. What I am sure of is a) if it's bad the no start typically happens on a warm/hot engine but it will start if cold and b) diagnosis is a simple as pulling the sensor, hooking up a volt/ohm meter, applying heat like from a hand held hair dryer, if resistance jumps all over the sensor is bad.

jeepdan · **Posted:** Wed Jul 16, 2014 12:30 pm

When I had my troubles with a failing crank sensor a few years back.
One incident that I remember, it wouldn't start for my daughter one evening, after driving to her friends house.
I went to see what was wrong, it started right up for me, and then went into limp mode with a transmission trouble code.
Shortly after that, I found and fixed the crank sensor.
Never had anymore transmission trouble codes after that.

CGman · **Posted:** Wed Jul 16, 2014 5:19 pm

If it cranks with no attempt to fire (especially after it was just running fine) I would check crank position sensor. Mine started off very intermittent and got worse. Two weeks now since replacing it (not a 30 minute job) and it's started every time in 1 to 2 seconds.

DocB · **Posted:** Wed Jul 16, 2014 6:11 pm

She starts and runs.
I believe, as suggested above, that it was air in fuel, or an air leak.
The filter was loose. No fuel leaking out, but when I went to turn it off, it was not tight at all.
I do not understand this, because I installed the filter, and believe me, it was tight.
Just got done cutting the fuel filter open and it was clean. I knew it would be, because I know where I always fill up.

Is it possible for filter to "come" loose?

CPS-I will have to look into this. What, where and how to replace.
Should I carry a spare in the Jeep like I do in the 7.3L Powerstroke?

But again, I parked it at night and it was running fine. Next morning, nada.

Maybe the fuel filter was a fluke, and as suggested, it might be the start of an intermittant CPS.
I will keep an eye on it.

Thanks Fellas!

papaindigo · **Posted:** Thu Jul 17, 2014 8:27 am

Not to doubt you tightened it but the fuel filter should not be able to come loose if properly tightened. To state the obvious when installing a new fuel filter be sure to lubricate BOTH the inner and outer gaskets with a bit of diesel fuel or oil (critical to being able to tighten the filter "enough"), spin the filter on until the gaskets "bottom" (e.g. firmly touch the sealing surface); and then tighten the filter an additional 1/2-3/4 turn. If you did not lube the gaskets or if you left the old inner gasket on (it's not uncommon for the old one to stick in place when the old filter is removed) then yes it's possible that the new filter was not fully tightened and could work loose.

Crank position sensor is on the turbo side of the engine. See pictures 7, 8, and 0 at viewtopic.php?f=98&t=74594 . You can carry a spare but I don't think it's critical or that the sensor is any more likely to fail than any other sensor. As I recall from past chats when the CPS is going the issue typical is failure to crank up when the sensor is hot not a failure to run if the vehicle cranks up.

DocB · **Posted:** Wed Aug 20, 2014 12:31 am

I would just like to take a moment to thank you fellas on this forum that post up with answers to our questions.
Without you guys, I would be LOST. Thank you again for your time, effort, and for the sharing of your knowledge.
And for the links to very relevant information, like pictures, and part numbers, of what we are talking about.

My "intermittant" no start was a direct cause of a bad CPS.
I changed it out, and so far, it starts all the time.

I would like to add a few things that may make it easier for someone else in the future who reads this and needs to install a new CPS.
Following the FSM instructions, and what has been posted here as access the the CPS, if I have to do it again, I will do what is listed below.
For me, it will be easier, better, and faster. Access, and room, are the problem. I was dicken around by not moving stuff out of the way.
I had problems disconnecting the plug, and getting the plug out of the bracket.
In hind sight, move stuff out of the way, get in, get out, and put stuff back.

1. Move coolant reservoir out of the way. No need to disconnect hoses.
2. Remove heat shield from top of turbo.
3. (from the bottom) Loosen nut on V-clamp from turbo downpipe, disconnect, and move downpipe outboard. Now you can see everything from top and bottom.
4. Remove heat shield over CPS.
5. Disconnect harness plug. Slide CPS plug out of bracket.
6. Remove bolt holding in CPS. Remove CPS.
7. Grease on O-ring. Install new CPS. Install bolt.
8. Slide plug into bracket. Connect harness plug. *Make sure tab on plug is toward front of vehicle.
9. Reinstall heat shield over CPS.
10. Reconnect downpipe to turbo.
11. Replace heat shield on top of turbo.
12. Put coolant reservoir back in place.

Submitted for your consideration.

DocB · **Posted:** Tue Aug 26, 2014 1:28 am

Update: Still starting just fine!

The Scott McLean · **Joined:** Tue Feb 15, 2011 9:19 pm **Posts:** 43

Hey DocB, have you noticed any running improvements since you installed the cps? I have no dieing out issues, or starting issues. however once and a while I do get a bad lag. Been thinking to replace the cps, original 190,000 Km's on it

DocB · **Posted:** Sun Aug 31, 2014 3:30 am

Not really. Just starts and runs great again.

? No Start ? Intermittant = Bad CPS, Fixed It

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