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HELP 05 Liberty Diesel P1202 Reoccurring
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=82620		 Page 1 of 1
Author:  esb12510 [ Thu Jul 16, 2015 9:48 pm ]
Post subject:  HELP 05 Liberty Diesel P1202 Reoccurring
I have a 2005 Liberty CRD with a P1202 code issue. The engine was just swapped into this Jeep from a donor which was also an '05. We used the engine, wiring harness and gateway module from the other jeep which was working prior to the swap. The ECM and TCM are from the new Jeep that the engine is currently in. After installation, the Jeep was throwing P1202 and P0102 codes (MAF unplugged, P0102 was expected). The EGR was blocked off due to what we thought was a sticky EGR valve. This didn't take care of the problem, so we thought it might be a computer issue. We tried swapping ECMs but the Jeep would start but shut off after just a few seconds (communication issue I would assume). Next, we turned to air issues in the fuel. A new 2nd gen filter head and filter as well as a lift pump were installed and all of the air has been worked out of the system. However, this didn't fix the problem either. It was found that if the engine is started and the codes are cleared the P1202 code will go away and stay away. However, if the engine is shut off (even for just a few seconds), then turned back on the P1202 code will come back and the engine will run terribly until the code is cleared again. So once the P1202 code is cleared the engine will run great but after shutting it off you're back to square one. By running terribly I mean that it'll rev up to about 3 grand then finally shift, sputter up hills, and have a total lack of power in general.
:dead:

Anyone had issues with this before or have an idea where to look next? I was thinking about the Flow Control Valve on the CP3? I'm confused as to why or how it could be a stuck regulator when if the code is simply cleared, the problem doesn't occur.

:dizzy:

Thanks in advance!
Author:  Billwill [ Fri Jul 17, 2015 3:42 am ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
esb12510 wrote:
I have a 2005 Liberty CRD with a P1202 code issue. The engine was just swapped into this Jeep from a donor which was also an '05. We used the engine, wiring harness and gateway module from the other jeep which was working prior to the swap. The ECM and TCM are from the new Jeep that the engine is currently in. After installation, the Jeep was throwing P1202 and P0102 codes (MAF unplugged, P0102 was expected). The EGR was blocked off due to what we thought was a sticky EGR valve. This didn't take care of the problem, so we thought it might be a computer issue. We tried swapping ECMs but the Jeep would start but shut off after just a few seconds (communication issue I would assume). Next, we turned to air issues in the fuel. A new 2nd gen filter head and filter as well as a lift pump were installed and all of the air has been worked out of the system. However, this didn't fix the problem either. It was found that if the engine is started and the codes are cleared the P1202 code will go away and stay away. However, if the engine is shut off (even for just a few seconds), then turned back on the P1202 code will come back and the engine will run terribly until the code is cleared again. So once the P1202 code is cleared the engine will run great but after shutting it off you're back to square one. By running terribly I mean that it'll rev up to about 3 grand then finally shift, sputter up hills, and have a total lack of power in general.
:dead:


Anyone had issues with this before or have an idea where to look next? I was thinking about the Flow Control Valve on the CP3? I'm confused as to why or how it could be a stuck regulator when if the code is simply cleared, the problem doesn't occur.

:dizzy:

Thanks in advance!


If you do a search here for this code there are a few hits for cylinder #2 Injector Connector or wiring to the injector or the injector itself. :?
Author:  esb12510 [ Fri Jul 17, 2015 8:06 am ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
Forgot to mention I did also unplug and check all the connections to the injectors. Everything looks good there.
Author:  bugnout [ Fri Jul 17, 2015 10:40 am ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
I know this sounds strange, but I got some very weird fuel system codes and limp mode a while back that ended up being the fuel temp sensor sensing out of range. I diagnosed it by disconnecting the sensor and inserting a resistor across the leads to get produce an in range value to the PCM. Can't remember what value it was, I'll see if I can dig up my notes. A short of the wires would produce an out of range value.
Author:  bugnout [ Fri Jul 17, 2015 10:58 am ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
Just looked back at my postings and it was in fact a P1202 code I was getting when the de-rating/fueling would occur.
Author:  bugnout [ Fri Jul 17, 2015 3:59 pm ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
100 Ohm resistor should correspond to about 25 Celsius reading for fuel temp.
Author:  esb12510 [ Fri Jul 17, 2015 10:29 pm ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
So we're getting a reading of 2.170 kilo ohms or 2170 ohms. Woah. According to your reference the temperature corresponding to that would be over 500 degrees Celsius.
:ALONE:

This is a new filter head too so the wire must be shorted out. Next step will be to insert a resistor. Will keep you updated. Thanks for your help so far!
Author:  bugnout [ Sat Jul 18, 2015 11:48 am ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
I don't think you can check resistance of the thermistor using an ohm meter. It requires a balanced circuit. But replacing the thermistor with a resistor will allow you to fool the ECM and verify the thermistor is the issue.
Author:  esb12510 [ Fri Jul 31, 2015 9:48 pm ]
Post subject:  Re: HELP 05 Liberty Diesel P1202 Reoccurring
Tried the resistor with no luck. Also checked the voltage and wiring to the injectors and everything seems fine there. Anyone else have any other ideas? I'm stumped on this one.
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