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Chrysler Repair/No Spark, Chrysler 300M 2004


QUESTION: Roland, something is wrong because I can no longer respond to our previous thread about my Chrysler 300M with no spark, codes 0122 0129 0335 0340, how do I get the thread to allow me to respond?  Do I need to start all over again?

ANSWER: There is a limit of 3 or 4 follow ups, here is what we covered so far:
QUESTION: I have a 2004 Chrysler 300M, 174K miles, and within the last 2K miles I replaced the timing belt, water pump and all tensioners/pulleys.  The 300M was purring along fine.  Until 3 days ago, when it wouldn't start.  I removed the timing cover and double-checked the timing belt, thinking that maybe the belt "stretched" and it jumped a tooth on one of the camshafts. No, that wasn't the problem.  I reassembled, then checked the fuel pump.  I could hear it run when I initially turned on the key. So I believe that is (at least) working.  But then I checked for spark on the front left cylinder (drivers side).  I removed the coil, then the plug, then turned the ignition.  No spark, and had my friend, a mechanic by trade, verify the "no spark condition."  This got his interest, so we checked for codes that are visible after turning the ignition on/off for 3 times, and leaving it on after the third time.  We got 4 codes to display at the Odometer window, the 1st being P0129, 2nd was P0122, 3rd was P0335 and the 4th was P0340.  We replaced the Crank/Camshaft sensors.  This did not fix the problem.  (We reset the computer codes after we installed the two sensors. We verified this be using the above mentioned on/off procedure and the car did not produce any codes, until AFTER we tried to start the car.  Then the 4 codes mentioned above returned).  We did not replace the TPI sensor because we believe this would not cause a NO SPARK condition.  (Yes?) That only leaves code 0129, and this item is located in the PCM, right?  I believe I have a bad computer, have I covered everything before attacking this ECM/PCM?

ANSWER: Hi Wade,
No, the 122 and 129 codes are for the tps and the map sensors, neither of which are located physically in the pcm. However, the one thing all four fault coded sensors share in common is a 5v supply voltage that they need to operate, and that does come from pin 29 of the pcm on a violet/white wire (it also goes to A/C pressure transducer). My thought is that the violet/white wire is either shorted to ground, or one of the sensors is shorting it to ground which of course would cause the 4 codes. So see whether or not you have 5v on that wire at any of the 5 sensors that is convenient. If not, then try disconnecting the plugs of the sensors one at a time to see if the 5v shows up on a violet/white at one of the disconnecting plugs that you monitor. I can tell you more about the harness connections of that wire from the pcm 29 pin if I am correct about the 5v not being available.
Please read the PS below and respond.

---------- FOLLOW-UP ----------

QUESTION: Would this also cause the no spark condition I am experiencing?  Has the computer shut down the car because it is not getting input from those four sensors?  In the morning I will perform the steps you recommended above and respond.  I will also honor your PS request above following the conclusion of our correspondence.  Thanks again....

ANSWER: Hi Wade,
Yes, if my theory is correct then the output from the cam/crank are missing entirely which means no spark will be generated by the pcm's not knowing what is going on with the engine rotational position, and also the signals from the other sensors are out of expectation (being 0v) which causes their codes and poor running if you did have spark.
So the pcm isn't shutting down the car, it just can't function without the signals from the rotational sensors. When you write back tell me which engine (L) you have, so if you can't find a sensor I can tell you where it is.
As to the PS request, you can either wait or do it after each answer that I send back. The website will 'count' towards a recognition of me up to 5 such nominations per questioner, so I will await your responses at your pleasure as we solve this situation.

---------- FOLLOW-UP ----------

QUESTION: Yes, I should have stated that in my first post...The engine is a 3.5L with Block Heater, 2004 Base 300M, 174211 miles.

The MAP sensor is on the left top of the engine near the spark coil for cyl 4.
The TPS is located at the upper side of the throttle body, and the A/C transducer is connected to the high pressure line of the compressor in the right lower front corner of the engine compartment (gray plug, 3-wires). Thanks for the ratings and nominations.

So go ahead...

---------- FOLLOW-UP ----------

QUESTION: We checked the violet/white wire to all 5 sensors (cam, crank, MAP, TPI, AC Transducer) and we had no opens or shorts in the wiring and we did not have the 5 vdc you referred to in your earlier response. Now, when we check the code at the Odometer window, we get codes P0129 and P0122 but no longer receiving codes P0335 and P0340, but the cam and crank sensors are new.  But we still have a no spark condition.  We visually inspected the ecm but found no burnt or bent pins, etc.  What might be our next step?

The only thing I am a bit surprised about is that the 0335 and 0340 codes are not showing, but it may be that more cranking over of the engine is needed for those to reappear. Without 5v at those cam/crank sensors there will be no pulsing signals which should then cause a code.
When you say you checked for opens and shorts in the violet/white harness, does that mean you removed the powertrain control gray plug that carries that wire on pin 29 and checked from that plug pin out to all 5 sensors and also verified that the wire was not shorted to ground?
If not, I would do that just to be certain that the harness assigned to distribute the 5V is good.
There are four 38-pin plugs at the pcm, the plug in question is between the black and white plugs and is gray in color. Then with that plug still removed, turn the ignition switch to run and measure the voltage on pin 29 of the unplugged socket at the pcm and verify whether or not the pcm is putting out the 5V. If not, then I would suspect a failure internal to the pcm as there is no incoming 12v poower on that removed gray plug so it should show 5v derived from 12v that comes in on one of the other 3 plugs.
Let me know what you learn. Another nomination would be much appreciated.

PS: If you find that the pcm is not putting out 5v on pin 29, then it would be good to check the following fuses which supply power to the pcm: in the box in the engine compartment fuses N and W, and the box behind the left end cap of the dash fuses 1 and 13.

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Roland Finston


Free fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question, briefly unavailable, or asleep overnight, so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2011 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top Expert" 2010-2015, here at AllExperts, and have answered 20,000+ questions.


Five decades as a 'do-it-yourselfer' on domestic and imported cars.

Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Advanced degrees in Physics/bruised knuckles

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014 and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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