Hot no start update

jeepdan · **Posted:** Tue Jan 10, 2012 10:32 am

GreenDieselEngineering wrote:

Mozzio,

Can you find a used relay box (BCM/TIPM) for the CRD in a junkyard? This is the relay box assembly in front of the battery. On a couple vehicles with hot start issues, when the box was changed it solved the issue. Not sure what fails on it, but it might be a last ditch effort for your CRD. GDE

So, one of the power circuits to the ECM may not be coming on line every time, due to a failing relay or connection?
That makes the most sense of the situation that I have. Either the jeep starts readily and runs well, or it doesn't fire at all without any codes.
In my case, I COULD switch relay boxes from one CRD to another to eliminate that possibility.

I ordered the Chrysler KJ Diesel Powertrain Diagnostics Manual. I hope that it can provide useful information.

Joe Romas · **Posted:** Tue Jan 10, 2012 10:40 am

whitedog wrote:

I have been reading this and following along, hoping for a good and definitive outcome. I come from the VW TDI world and on some of the cars, there was some stock mapping that makes for hard starting when hot, but a tune takes care of that. Now, i know that this isn't a problem with the stock tuning like in my Beetle, but is it possible that somehow the mapping has become corrupted? I hate to throw out a wild theory without a suggestion on how to test it, but maybe Keith at GDE would have a suggestion?

Actually, now that I think about it a moment, if my Beetle is hot and I unplug the CTS, the ECU thinks it's cold, so it reverts to the cold start map. Maybe there is a comparable way to fool the ECU into thinking it's cold?

Just a thought.

I had a 1999.5 (A4 body) Jetta that had the warm start problem. The situation is the ECM is looking for a certain cranking rpm speed when hot and the starter that is weak to begin with won't crank it fast enough. My son has the Jetta now and a Rocket Tune from Jeff and he eliminated that "feature" :BANANA:

Being both the TDI and CRD ECM's are Bosch so that "feature" could be on both.
All I know is with my new Sears P1 battery the engine cranks faster then it ever did and my 50 degree and below delayed start is completly eliminated.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

GreenDieselEngineering wrote:

Mozzio,

Can you find a used relay box (BCM/TIPM) for the CRD in a junkyard? This is the relay box assembly in front of the battery. On a couple vehicles with hot start issues, when the box was changed it solved the issue. Not sure what fails on it, but it might be a last ditch effort for your CRD. GDE

Thank you for the idea. I had forgotten that years a go and around the time my symptoms first started appearing my jeep left me stuck at a truck stop 200 miles from home. Noticed one of the relays had popped out of that box(was actually upside down) and just stuck it back in. Didn't think much of it at the time and the dealer made it seem like no big deal.
Seems like I'm may not be driving off a cliff or swimming in a lake. Thanks for the jarring of my memory.

papaindigo · **Posted:** Tue Jan 10, 2012 3:49 pm

Any chance you can identify what relay? Sounds like a loose relay connection problem that could easily get worse as things get warm. I know when I pulled my viscouse heater relay it was plugged in so tight I had to gently grab it pliers and wiggle a bit to get it loose.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

papaindigo wrote:

Any chance you can identify what relay? Sounds like a loose relay connection problem that could easily get worse as things get warm. I know when I pulled my viscouse heater relay it was plugged in so tight I had to gently grab it pliers and wiggle a bit to get it loose.

#38 I/2 Relay Fuel Priming Pump from lid
Service manual shows it as a spare though.

jeepdan · **Posted:** Wed Jan 11, 2012 1:16 am

After reading from the FSM, I won't try switching Power Distribution Centers from one CRD to another. The PSD box is permanently attached to the headlamp and dash wire harness. I will start with testing relays and disassemble the Power Distribution Center to look for anything obvious.

jeepdan · **Posted:** Sun Jan 15, 2012 9:47 pm

I wish I had something new and positive to report, but I don't

.
All five of the power inputs (three from the ASD relay, two from the ignition switch) and the three grounds at the ECM connector test OK. And all of the solenoid and sensor wiring circuits tested OK for continuity.
But, :?:

I do not have, anyway of knowing from one minute to the next whether the gremlin was present during the time of testing. :juggle:

I have not tested the Crankshaft Sensor wiring yet though, as I could not readily access it to test. I'm thinking that I may replace the Crankshaft Sensor so I will test that wiring then.
I also removed the lower cover from the Power Distribution Center to check for pushed out terminals or any overheated or damaged wiring.

With the way that the jeep either doesn't fire at all or it might fire up quickly a minute later, makes me wonder if something sinister is going wrong in the ECM :grim:

msilbernagel · **Posted:** Sun Jan 15, 2012 10:59 pm

mozzio wrote:

Jeepdan, after reading your post I guess I have the same decision to make,
I installed the pump out of a dodge 3500 hoping to avoid that issue.
Does anyone know if the pressure from that pump may be too great?

I've had a dodge (cummins/ram pickup) in-tank fuel pickup/pump for over 130,000 miles and it's worked flawlessly. Since it's designed to work with the Bosch CP3 on the Cummins engine in that truck - I would not expect issues in the Jeep - and haven't noticed any.

FYI - Mark

jeepdan · **Posted:** Wed Jan 18, 2012 5:07 pm

OK, After checking all of the relays, fuses, wiring circuits and not finding anything wrong. I ordered and installed the Engine Coolant Sensor and the Crankshaft Position/Speed Sensor. During two test drives today, the CRD has started great twelve times!! :BANANA:

An hour ago, I connected an Ohm meter to the old Crankshaft Sensor signal terminals and the laid the sensor on the hot engine block.
Within minutes the resistance of the sensor was all over the place, from high resistance to an open circuit. Just to make sure of what I was seeing, I duplicated the test on the work bench with a heat gun directed at the sensor, same results.
This has been a very frustrating, but very educational ordeal for me over the last few months. :dizzy:

I also spent a lot of money on expensive parts that I didn't need, I guess that is part of the learning process as well. :oops:

whitedog · **Posted:** Wed Jan 18, 2012 5:21 pm

I wonder if the tach was reading while cranking when hot.

jeepdan · **Posted:** Wed Jan 18, 2012 5:31 pm

The tach has always read correctly compared to my other CRD, but I don't think that I ever looked at the tach while cranking with the starter, good point. One thing of interest is that, the wiring diagram shows that there are two sensor signals from the one sensor. I don't know if one is redundant or what.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

I am still waiting to get the crankshaft sensor installed.
Hope I am as jubilant as you with the results.
The bench test sure sounds difinitive.

Thanks for the pm's.

msilbernagel · **Posted:** Wed Jan 18, 2012 6:20 pm

jeepdan wrote:

OK, After checking all of the relays, fuses, wiring circuits and not finding anything wrong. I ordered and installed the Engine Coolant Sensor an the Crankshaft Position/Speed Sensor. During two test drives today, the CRD has started great twelve times!! :BANANA:

An hour ago, I connected an Ohm meter to the old Crankshaft Sensor signal terminals and the laid the sensor on the hot engine block.
Within minutes the resistance of the sensor was all over the place, from high resistance to an open circuit. Just to make sure of what I was seeing, I duplicated the test on the work bench with a heat gun directed at the sensor, same results.
This has been a very frustrating, but very educational ordeal for me over the last few months. :dizzy:

I also spent a lot of money on expensive parts that I didn't need, I guess that is part of the learning process as well. :oops:

Amazing! These intermittent issues are *the* hardest problems to solve!

Now you know why so many shops end up throwing expensive parts and labor at our issues only to send us home with both the original problem AND the invoice! Serious empathy there...

May your fix last forever, bro. :rockon:

Mark

2mopar_diesels · **Posted:** Wed Jan 18, 2012 8:06 pm

Also glad to see this fixed!!! Sorry I was one of the guys to lead you astray.........but look on the bright side, at least you weren't paying someone else to find and fix this problem. And you really help others out who will likely have the same issues in the future and Dave then the time, money, and hassle you've had. Thanks fir your service to this community!!!!!

racertracer · **Posted:** Wed Jan 18, 2012 8:20 pm

Excellent.... may your fix last forever and may the force be with you too.

whitedog · **Posted:** Wed Jan 18, 2012 9:02 pm

mozzio wrote:

I am still waiting to get the crankshaft sensor installed.
Hope I am as jubilant as you with the results.
The bench test sure sounds difinitive.

Thanks for the pm's.

Mozzio, how about your tach? Does it move when cranking/not starting?

427cobra · **Joined:** Thu Nov 24, 2011 11:02 am **Posts:** 6

Hello could some one give me the brand & part number to the crankshaft & camshaft sensor. Thanks

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

I've never paid attention to it.
I will look tomorrow when I try to start it hot.
Don't know the part number off hand, just ordered it from mopar parts america.
There new parts diagrams help make it easier. They do not list part numbers.

KhakiCRD · **Posted:** Wed Jan 18, 2012 11:32 pm

JeepDan, I'm glad you tried the crank position sensor. I put one in a couple weeks ago and it has been running great ever since. We just drove over 1000 miles last weekend without any issues. I bench tested my old one as well. It seemed fine when cold, but once i warmed it up the resistance skyrocketed. Well I'm sure we'll have some other tricky problems with this little diesel.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

Yes, my tach read correctly when it would not start.
Engine was spinning just a little over 200 rpm's.
Trying to get the libby in the shop this am, we'll see.

Hot no start update

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